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Report to Congressional Requesters: 

United States Government Accountability Office: 

GAO: 

June 2006: 

Clean Air Act: 

EPA Should Improve the Management of Its Air Toxics Program: 

Clean Air Act: 

GAO-06-669: 

GAO Highlights: 

Highlights of GAO-06-669, a report to congressional requesters 

Why GAO Did This Study: 

The Environmental Protection Agency’s (EPA) most recent data indicate 
that 95 percent of all Americans face an increased likelihood of 
developing cancer as a result of breathing air toxics—pollutants such 
as benzene and asbestos that may cause cancer or other serious health 
problems. Sources of air toxics include large industrial facilities, 
smaller facilities such as dry cleaners, and cars and trucks. The 1990 
Clean Air Act Amendments required EPA to regulate 190 pollutants from 
these sources through a multifaceted regulatory program. While EPA 
issues federal standards, state and local agencies generally administer 
these standards, and some develop their own rules to complement the 
federal standards. In this context, GAO was asked to assess (1) EPA’s 
progress and challenges in implementing the air toxics program, (2) 
available information on the program’s costs and benefits, and (3) 
practices of state and local air toxics programs. 

What GAO Found: 

While EPA has made some progress in implementing its air toxics program 
mandated by the 1990 Clean Air Act Amendments, most of its regulatory 
actions were completed late and major aspects of the program have still 
not been addressed. Most of EPA’s progress relates to issuing emissions 
standards for large stationary sources, although EPA completed these 
standards about 4 years behind schedule. However, many of the unmet 
requirements pertain to limiting emissions from small stationary and 
mobile sources, which collectively account for most emissions of air 
toxics. The agency faces continuing implementation challenges stemming 
from the program’s low priority relative to other programs and related 
funding constraints. To this end, the agency lacks a comprehensive 
strategy for completing the unmet requirements or estimates of 
resources necessary to do so. Senior EPA officials said the program’s 
agenda is largely set by external stakeholders who file litigation when 
the agency misses deadlines. As a result of EPA’s limited progress, the 
agency has not addressed health risks from air toxics to the extent or 
in the time frames envisioned in the Clean Air Act. Senior EPA 
officials said that issuing standards for large stationary sources had 
addressed the greatest risks from air toxics and that other clean air 
programs also control air toxics as a side benefit. However, EPA does 
not have reliable data on the degree of risk reduction achieved through 
its regulations. Furthermore, the data that are available suggest that 
the agency has substantial opportunities to reduce emissions from 
mobile and small stationary sources. 

Available information on EPA’s efforts to control air toxics is not 
sufficiently comprehensive to measure the program’s total costs and 
benefits. Specifically, EPA has not comprehensively estimated the 
national economic costs of all air toxics standards and lacks the data 
necessary to assess the benefits of these standards, such as decreased 
incidence of cancer. Information on these impacts would help the agency 
assess the overall net benefits (total benefits minus total costs) of 
the air toxics program and compare these effects with those generated 
by higher-priority clean air programs, such as those intended to 
address smog. Data on other indicators of the program’s effectiveness, 
such as changes in emissions, concentrations of air toxics in the 
(ambient) outdoor air, and data on compliance with air toxics standards 
are also limited and inconclusive. 

The state and local programs we reviewed use practices that could 
potentially help EPA enhance the effectiveness of its air toxics 
program. For example, several state programs have systematic approaches 
for identifying and prioritizing new pollutants that could inform EPA’s 
efforts to meet the act’s requirement to review and update the list of 
regulated pollutants. 

What GAO Recommends: 

GAO recommends that EPA develop a plan for improving the management of 
its air toxics program, including a prioritization scheme, timelines, 
and estimates of resources needed to meet its statutory obligations. 
EPA agreed, in part, with our conclusions and recommendations, and 
provided clarifications on three statements in the report. 

[Hyperlink, http://www.gao.gov/cgi-bin/getrpt?GAO-06-669]. 

To view the full product, including the scope and methodology, click on 
the link above. For more information, contact John Stephenson at (202) 
512-3841 or stephensonj@gao.gov. 

[End of Section] 

Contents: 

Letter: 

Results in Brief: 

Background: 

EPA Has Made Limited Progress in Addressing the Clean Air Act's 
Requirements for Air Toxics and Faces Significant Implementation 
Challenges: 

Available Information on Costs and Benefits Is Not Sufficient to 
Measure the Program's Effectiveness: 

State and Local Programs Employ Practices That Could Potentially Help 
EPA Enhance the Effectiveness of the Federal Air Toxics Program: 

Conclusions: 

Recommendations for Executive Action: 

Agency Comments: 

Appendix I: Status of EPA's Efforts to Respond to Recommendations in 
the National Academies' Report on Air Quality: 

Appendix II: Objectives, Scope, and Methodology: 

Appendix III: Profiles of State and Local Air Toxics Programs: 

California: 
New Jersey: 
Oregon: 
Wisconsin: 
Louisville, Kentucky: 

Appendix IV: Comments from the Environmental Protection Agency: 

GAO comments: 

Appendix V: GAO Contact and Staff Acknowledgments: 

Tables: 

Table 1: The Five Most Commonly Emitted Air Toxics, 2002: 

Table 2: Overview of the Risk Assessment Process: 

Table 3: Number of Air Toxics Actions Required under the 1990 Clean Air 
Act Amendments: 

Table 4: EPA Progress in Meeting Air Toxics Requirements: 

Table 5: Timeliness of MACT Emission Control Standards for Major Source 
Categories: 

Table 6: EPA Funding for Air Toxics Program as a Percentage of Funding 
for All Clean Air Programs, Fiscal Years 2000 through 2005: 

Table 7: Percentage of Estimated Total Air Toxics Emissions by Source 
Type, 1993, 1999, and 2002: 

Table 8: Issues Rated by Stakeholders as Challenges to a Large or Great 
Extent: 

Table 9: Summary of Annual Costs Imposed by the 1990 Clean Air Act 
Amendments: 

Table 10: Key Steps in Estimating the Benefits of Controlling Air 
Toxics: 

Table 11: Results of Inspections at Facilities Regulated by Air Toxics 
Standards, 2003 and 2004: 

Table 12: Selected State and Local Air Toxics Programs: 

Figures: 

Figure 1: Common Sources of Air Toxics Emissions: 

Figure 2: EPA Air Toxics Regulatory Framework for Major Stationary 
Sources: 

Figure 3: Emission Points at an Industrial Facility Emitting Air 
Toxics: 

Abbreviations: 

CRS: Congressional Research Service: 
DEP: New Jersey Department of Environmental Protection: 
DEQ: Oregon Department of Environmental Quality: 
DNR: Wisconsin Department of Natural Resources: 
EPA: Environmental Protection Agency: 
IRIS: Integrated Risk Information System: 
MACT: Maximum Achievable Control Technology: 
NATA: National Air Toxics Assessment: 
NSPS: New Source Performance Standards: 
OAQPS: Office of Air Quality Planning and Standards: 
OAR: Office of Air and Radiation: 
OMB: Office of Management and Budget: 
OPAR: Office of Policy Analysis and Review: 
ORD: Office of Research and Development: 
SAB: Science Advisory Board: 
STAPPA/ ALAPCO: State and Territorial Air Pollution Program 
Administrators and the Association of Local Air Pollution Control 
Officials: 
STAR: Strategic Toxic Air Reduction: 

United States Government Accountability Office: 
Washington, DC 20548: 

June 23, 2006: 

Congressional Requesters: 

The Environmental Protection Agency's (EPA) most recent data indicate 
that 95 percent of all Americans face an increased likelihood of 
developing cancer from air toxics--pollutants such as benzene, 
asbestos, and chlorine--by breathing outdoor air.[Footnote 1] Other 
adverse health effects associated with air toxics include damage to 
reproductive functions and birth defects.[Footnote 2] Air toxics are 
emitted into the air in the United States by large stationary sources 
such as industrial facilities, small stationary sources such as dry 
cleaners, and mobile sources such as automobiles. According to the most 
recent data available, EPA estimates that these and other sources 
emitted 4.6 million tons of air toxics in 2002.[Footnote 3] The Clean 
Air Act of 1970 established a program to reduce emissions of air 
toxics, and the 1990 amendments to the act significantly expanded the 
program. Prior to the amendments, the act had required EPA to identify 
air toxics that posed unacceptable health risks and issue emissions 
standards for sources of these pollutants. In part because of the 
limited success of this approach--EPA established standards for seven 
air toxics over a 20-year period--the amendments identified 190 
specific air toxics to be regulated, required EPA to list categories of 
sources to be regulated, and established implementation timelines. 

Specifically, the 1990 amendments established a range of air toxics 
requirements for EPA to implement that generally fall into four 
categories: (1) establishing emission standards based on existing 
pollution control technologies, called Maximum Achievable Control 
Technology (MACT), for an estimated 84,000 major stationary sources 
within 158 industries;[Footnote 4] (2) examining the remaining health 
risk (called the "residual risk") from these sources 8 years after 
implementing each MACT standard and, if warranted, issuing additional 
standards to protect public health or the environment; (3) regulating 
air toxics emissions from small stationary sources,[Footnote 5] such as 
dry cleaners; and (4) evaluating the need for and feasibility of 
regulation of air toxics emissions from mobile sources, such as cars, 
and regulating these sources based on this evaluation. In addition, the 
1990 amendments required EPA to periodically assess the costs and 
benefits of the entire Clean Air Act. This included an assessment of 
the act's costs and benefits prior to 1990 as well as projections of 
future economic impacts resulting from the amendments. Information on 
impacts, such as the costs to regulated industries and the public 
health benefits resulting from cleaner air, is necessary for analyzing 
whether the benefits of clean air regulations exceed the costs. 
Furthermore, estimating the economic impacts of individual regulations 
and clean air programs can help EPA compare the net benefits and cost- 
effectiveness of its programs under the act. Finally, the amendments 
required EPA to periodically review and revise the list of regulated 
air toxics. The agency currently regulates 187 substances.[Footnote 6] 

Prior GAO work dating to 1991 identified EPA's difficulties in 
regulating air toxics, including missed deadlines and inadequate 
funding.[Footnote 7] Most recently, a May 2005 GAO report found that 
EPA had completed MACT standards for major stationary sources but 
issued most of them behind schedule.[Footnote 8] In addition, the EPA 
Inspector General, National Academies, Congressional Research Service, 
and Office of Management and Budget (OMB) have identified shortcomings 
with various aspects of the air toxics program. 

While responsibility for establishing federal standards under the Clean 
Air Act rests with EPA, state and local air pollution control agencies 
generally implement EPA's emission standards. The act allows these 
agencies to impose more stringent requirements than the federal 
standards, and some state and local agencies have developed innovative 
air toxics programs that go beyond the federal program, thereby 
enabling them to address air toxics concerns that remain unaddressed by 
EPA's standards. 

In this context, you asked us to assess (1) EPA's progress toward 
implementing the air toxics program and any implementation challenges 
the agency faces, (2) available information about the costs and 
benefits of EPA's efforts to control air toxics, and (3) the program 
design and management practices of state and local air toxics programs 
that could potentially help EPA enhance the effectiveness of the 
federal program. You also asked us to assess EPA's progress in 
responding to recommendations pertaining to the air toxics program made 
by the National Academies in 2004.[Footnote 9] 

To respond to the first objective, we updated our previous analysis of 
the agency's progress in implementing the air toxics requirements under 
the Clean Air Act and reviewed available studies by the National 
Academies, OMB, and the EPA Inspector General to identify potential 
implementation challenges. Based on this information, we conducted 
structured interviews with EPA officials and external stakeholders to 
identify the most important challenges. We met with senior air program 
officials to discuss the priority of the air toxics program relative to 
other air programs as well as priorities within the program. To respond 
to the second objective, we analyzed available information on the 
economic impacts of the program and data on trends in emissions, health 
risks, and compliance. We also met with EPA staff responsible for 
analyzing the economic effects of clean air regulations. To respond to 
the third objective, we conducted interviews with officials from a 
nonprobability sample of four state and one local air toxics programs 
to identify innovative program designs or management practices. Among 
other criteria, we selected programs identified as innovative by EPA 
and other stakeholders and that used strategies that differ from those 
at the federal level. We focused primarily on practices that EPA might 
find useful in addressing its program implementation challenges and did 
not evaluate the effectiveness of these programs. Finally, we obtained 
information from EPA officials on the agency's progress in responding 
to the National Academies' recommendations pertaining to air toxics and 
describe the status of these efforts in appendix I. Our work included 
an assessment of data reliability and internal controls. Unless 
otherwise noted, data are sufficiently reliable for the purposes of 
this report. See appendix II for a more detailed description of our 
scope and methodology. We conducted our work from June 2005 to June 
2006 in accordance with generally accepted government auditing 
standards. 

Results in Brief: 

While EPA has made progress toward implementing the air toxics program 
mandated by the Clean Air Act, most of the completed requirements were 
met late and many requirements and significant challenges remain. EPA 
has completed one of the four categories of requirements--issuing 96 
rules that set emissions standards for major stationary sources--but 
did not do so until 2004, which was 4 years behind the schedule 
outlined in the act. These delays, in turn, pushed back the evaluation 
of the residual health risks from these sources that EPA must complete 
8 years after issuing each standard. Consequently, EPA will not 
complete the residual risk reviews--which are intended to provide 
information on any potential adverse health effects that may warrant 
further regulation--until 2012 at the earliest, rather than in 2008 as 
the act provided. Further, EPA has completed only 16 of 70 emissions 
standards for small stationary sources that cumulatively accounted for 
about one-third of all air toxic emissions in 2002 and has proposed, 
but not finalized, a required rule making covering mobile sources. 
Finally, EPA has not met the act's requirement to review and update, as 
appropriate, the list of regulated air toxics, despite evidence that 
potentially harmful chemicals remain unregulated. As a result of EPA's 
limited progress, the agency has not identified and reduced health 
risks from air toxics to the extent and in the time frame envisioned in 
the act. EPA's limited progress to date stems, in part, from the 
program's low priority relative to other air programs, such as those 
targeting smog, which the agency believes have a higher potential to 
reduce human health risks. Senior program officials also said that the 
agency's progress in implementing the act's requirements does not 
reflect all of the agency's progress in limiting toxic emissions 
because other EPA programs decrease emissions of air toxics as a side 
benefit. In addition, within the air toxics program, senior EPA 
officials said that the agency's focus on issuing emissions standards 
for major stationary sources had addressed the greatest risks from air 
toxics. However, EPA does not have reliable data on the degree to which 
its programs have reduced risks. Furthermore, the data that are 
available suggest that the agency still has substantial opportunities 
to control emissions from mobile and small stationary sources. 

EPA faces significant challenges in implementing the air toxics 
program, many of which stem from its relatively low priority within the 
agency. Importantly, the agency lacks a comprehensive strategy for 
managing its implementation of the remaining air toxics requirements. 
Senior EPA officials said that the program's agenda is largely set by 
external stakeholders who file litigation when the agency misses 
deadlines. For example, EPA currently faces a court order to issue 
emissions standards for small stationary sources. Previous reports by 
GAO identified inadequate funding for the air toxics program as a 
challenge, and key stakeholders--including senior EPA officials, 
environmental advocates, and state and local agency officials--said 
resource constraints continue to pose a major challenge. The percentage 
of funding for the air toxics program relative to all clean air 
programs ranged from 18 percent to 19 percent between 2000 and 2003 and 
declined to 15 percent in 2004 and 12 percent in 2005. EPA has not 
estimated the level of resources necessary to comply with the remaining 
requirements of the 1990 amendments, according to a senior program 
official. We believe that such estimates would help inform 
congressional oversight and appropriations decisions. Senior EPA 
officials and other stakeholders also cited a lack of information on 
the benefits of regulating air toxics as a major challenge, which, in 
turn, reinforces the program's relative priority because the agency 
cannot demonstrate its effectiveness. The stakeholders identified a 
number of other challenges, but perceptions varied by stakeholder 
group. For example, EPA and industry stakeholders rated the large 
number of statutory requirements as a challenge, while environmental 
stakeholders rated a lack of reliable data on air toxics sources and 
their emissions as a challenge. 

Available information on the costs and benefits of EPA's efforts to 
control air toxics is not sufficiently comprehensive to measure the 
total economic impacts resulting from the air toxics program. As a 
result, it is difficult to compare the net benefits (total benefits 
minus total costs) of EPA's investments in the air toxics program with 
those of other air quality programs. The agency's 1999 report 
responding to the act's mandate for a comprehensive cost-benefit 
analysis of all Clean Air Act programs contained limited information on 
the costs of regulating air toxics and no estimates of the human health 
benefits, such as likely reductions in cancer risk. The analysis 
estimated that the cost to industry of complying with the 21 control 
standards that had been issued by 1999 would total $780 million in 2000 
and rise to $840 million in 2010. EPA officials said the agency plans 
to issue a revised analysis in 2007 that will estimate the costs of all 
standards issued before September 2005. However, the analysis will only 
provide limited data on the benefits of regulating air toxics because 
of the analytical challenges involved. These challenges include a lack 
of reliable data on changes in emissions attributable to air toxics 
regulations and difficulties in estimating the effects that changes in 
emissions have on health outcomes. Specifically, EPA has not monetized 
the health benefits of its air toxics regulations individually or in 
total because of the analytical difficulty of characterizing health 
outcomes associated with incremental reductions in exposure to 187 
different chemicals. Instead of using a cost-benefit analysis to 
measure the program's effectiveness, EPA uses data on national trends 
in emissions of all air toxics. However, as EPA's Inspector General 
reported in 2004, the agency needs to improve its methods for 
estimating emissions before it can accurately gauge the extent to which 
its programs have actually reduced emissions. Other indicators of the 
program's effectiveness, such as changes in concentrations of air 
toxics in the ambient (outdoor) air over time and data on compliance 
with air toxics standards, are also limited and inconclusive. For 
example, the agency's data on compliance with air toxics standards 
cannot be generalized to describe compliance at the universe of 
regulated facilities because inspectors often target facilities where 
they suspect noncompliance. 

The five state and local air toxics programs we reviewed use several 
program design and management practices that EPA could consider as part 
of efforts to enhance the effectiveness of the federal air toxics 
program. First, the programs we reviewed address gaps in the federal 
program by, for example, regulating more emissions sources than EPA, or 
setting more stringent standards to control emissions. As part of 
efforts to strengthen its program and establish priorities for meeting 
its remaining obligations under the act, EPA could benefit from 
assessing and considering what states perceive as the primary gaps in 
the federal program. Second, these programs use risk-based approaches 
to prioritize efforts to control air toxics. For example, Oregon's air 
toxics program is designed to monitor emissions in various parts of the 
state, identify areas of elevated risk from air toxics, and then 
concentrate resources on the emissions sources that drive these risks. 
Third, some of these programs base their regulatory decisions on the 
risk posed by entire facilities, whereas, to date, EPA has limited the 
scope of its residual risk program to only those emission points within 
facilities that must comply with existing federal standards. As a 
result, according to several state and local officials, EPA's decision 
to exclude some emissions points from risk assessments may, in turn, 
cause it to underestimate the total risk from facilities and thereby 
enable some facilities to avoid further regulation. Fourth, several of 
the programs we reviewed have systematic approaches for identifying and 
prioritizing new chemicals. In contrast, EPA does not proactively 
consider new chemicals and instead has taken a reactive approach in 
which it considers petitions from external parties to list or delist 
chemicals. Considering the practices used by these programs could 
inform future EPA efforts to meet the act's requirement to periodically 
review and update the list of regulated chemicals. In addition to these 
practices, all of the programs we reviewed highlighted the importance 
of reliable data on emissions and chemical toxicity. Several require 
major and small stationary sources to submit standardized emissions 
reports and certify their accuracy. In contrast, EPA, to date, 
generally has not required emissions sources or state or local agencies 
to systematically report these data. Such standardized data collection 
could enhance EPA's analysis and decision making in future air toxics 
rule makings. In addition, several officials said that EPA does not 
regularly update chemical toxicity values that inform the work of state 
and local programs. 

We are recommending that EPA develop an air toxics program improvement 
plan that, among other things, (1) provides a schedule for completing 
its mandated requirements under the act and identifies the resources 
necessary to complete these actions, (2) prioritizes activities within 
the air toxics program, (3) establishes a process and timeline for 
meeting the act's requirement to review and update the list of air 
toxics, (4) outlines an approach and timelines for improving the 
agency's ability to measure the program's costs and benefits, and (5) 
describes how the agency plans to improve its air toxics emissions 
inventory. In commenting on the report, EPA's Acting Assistant 
Administrator for Air and Radiation said that EPA agrees in part with 
our conclusions and recommendations. The agency did not identify 
specific aspects of our conclusions or recommendations with which it 
disagreed, but offered clarifications on our statements regarding 
information on the costs and benefits of the agency's efforts to 
control air toxics, the agency's progress in completing certain air 
toxics requirements of the Clean Air Act, and EPA's management of the 
remaining requirements. EPA also provided technical comments, which we 
have incorporated, as appropriate. EPA's letter, and our response, are 
included as appendix IV. 

Background: 

Under the Clean Air Act, EPA regulates two primary types of air 
pollutants. The first category--the so-called "criteria pollutants" for 
which EPA has established air quality criteria that limit the allowable 
concentrations in the ambient air--includes carbon monoxide, ground- 
level ozone (smog), lead, nitrogen oxides, particulate matter, and 
sulfur dioxide. EPA sets these standards at a level it believes 
protects public health and the needs of sensitive populations such as 
asthmatics, children, and the elderly. EPA and the states use air 
quality monitoring to measure compliance with the standards and develop 
pollution control strategies to help bring areas with poor air quality 
into compliance. 

The second category consists of hazardous air pollutants (or "air 
toxics") for which no ambient air quality standards exist, and includes 
187 chemicals that cause a variety of adverse health effects, including 
cancer. A variety of sources emit one or more of these air toxics (see 
fig. 1). In 2002, mobile sources emitted 41 percent of all air toxics, 
small stationary sources emitted 30 percent, major stationary sources 
emitted 20 percent, and other sources, such as fires, emitted 9 
percent, according to EPA's most recent data. 

Figure 1: Common Sources of Air Toxics Emissions: 

[See PDF for image] 

Source: EPA (data); GAO, ARt Explosion (image). 

[End of figure] 

Table 1 identifies the most widely emitted air toxics, the primary 
sources of these pollutants, and some of the adverse health effects 
associated with exposure to these substances. It is important to note 
that the health risks posed by air toxics vary considerably. Thus, 
small quantities of more harmful pollutants can pose greater health 
threats than large quantities of less harmful pollutants. 

Table 1: The Five Most Commonly Emitted Air Toxics, 2002: 

Pollutant: Toluene; 
Percentage of total air toxics emissions: 18; 
Primary sources of emissions: Mobile sources; 
Health effects: Impairment of the nervous system with symptoms 
including tiredness, dizziness, sleepiness, confusion, weakness, memory 
loss, nausea, loss of appetite, and hearing and color vision loss; 
kidney problems; unconsciousness; and death. 

Pollutant: Xylenes; 
Percentage of total air toxics emissions: 13; 
Primary sources of emissions: Mobile sources, asphalt paving; 
Health effects: Irritation of the skin, eyes, nose, and throat; 
headaches, dizziness, memory loss, and changes in sense of balance; 
lung problems; stomach discomfort; possible effects on the liver and 
kidneys; unconsciousness; and death. 

Pollutant: Hydrochloric acid; 
Percentage of total air toxics emissions: 12; 
Primary sources of emissions: Coal-fired utility and industrial 
boilers; 
Health effects: Eye, nose, and respiratory tract irritation; corrosion 
of the skin, eyes, mucous membranes, esophagus, and stomach; severe 
burns; ulceration; scarring; inflammation of the stomach lining; 
chronic bronchitis; and inflammation of the skin. 

Pollutant: Benzene; 
Percentage of total air toxics emissions: 9; 
Primary sources of emissions: Mobile sources, open burning, pesticide 
application; 
Health effects: Drowsiness, dizziness, vomiting, irritation of the 
stomach, sleepiness, convulsions, rapid heart rate, headaches, tremors, 
confusion, unconsciousness, anemia, excessive bleeding, weakened immune 
system, increased incidence of cancer (leukemia), and death. 

Pollutant: Formaldehyde; 
Percentage of total air toxics emissions: 7; 
Primary sources of emissions: Mobile sources, open burning; 
Health effects: Irritation of the eyes, nose, throat, and skin; severe 
pain; vomiting; coma; limited evidence of cancer; and death. 

Sources: EPA and Agency for Toxic Substances and Disease Registry. 

Note: Health effects are dependent upon the concentration of the air 
toxic and the length of exposure. 

[End of table] 

Prior to 1990, the Clean Air Act required EPA to list air toxics it 
deemed hazardous and then promulgate regulations for them. However, by 
1990, EPA had regulated only seven such pollutants. In 1990, Congress 
dramatically changed the program. Instead of requiring EPA to develop 
ambient standards for air toxics as it does for the six criteria 
pollutants, the Clean Air Act Amendments of 1990 listed the air toxics 
to be controlled and directed EPA to control them by, among other 
things, (1) developing technology-based emissions limits (MACT 
standards) for major stationary sources, such as incinerators and 
chemical plants; (2) regulating emissions from smaller sources, such as 
dry cleaners and gas stations; and (3) evaluating the need for and 
feasibility of regulations from mobile sources, such as cars, and 
regulating these sources based on this evaluation. The standards for 
major stationary sources generally require the use of available control 
technologies to achieve emissions reductions without the explicit 
consideration of a chemical's toxicity or potential risk. To develop 
MACT standards, the 1990 amendments directed EPA to group emissions 
points at industrial facilities into categories of similar sources and 
then develop regulations for each "source category." Examples of source 
categories include cement manufacturing, hazardous waste combustion, 
and semiconductor manufacturing.[Footnote 10] The next step consisted 
of evaluating the level of emissions control achieved by the best- 
performing facilities in each source category and using this as the 
minimum level of control required throughout the entire source 
category.[Footnote 11] 

Additionally, the amendments required EPA to review the MACT standards 
every 8 years to evaluate any remaining, or residual, health risks from 
these sources and identify developments in control technologies. EPA 
has combined the residual risk assessments and technology reviews into 
a concurrent process. Thus, the agency simultaneously evaluates the 
remaining risks from each source category and the availability of new 
pollution control technologies. The risk assessment process seeks to 
estimate the cancer and other health risks faced by individuals exposed 
to toxic emissions. As shown in table 2, the four steps of risk 
assessment include hazard identification, dose-response assessment, 
exposure assessment, and risk characterization. 

Table 2: Overview of the Risk Assessment Process: 

Step: Hazard identification; 
Description: Determine the association between pollutants and adverse 
health effects. This involves reviewing studies of illnesses among 
groups of people or laboratory animals exposed to air pollutants. 

Step: Dose-response assessment; 
Description: Describe the adverse health effects associated with 
different levels of exposure to a particular pollutant. 

Step: Exposure assessment; 
Description: Estimate the amount of an air toxic a person is likely to 
inhale in a given period of time using data on emissions, 
meteorological conditions, and information on the locations of homes 
and workplaces relative to emissions sources. 

Step: Risk characterization; 
Description: Integrate the information from the three previous steps to 
describe the degree of increased risk faced by individuals. Typical 
results of this step include measures of excess lifetime cancer risk 
(e.g., a risk of 100 in 1 million), the population risk (e.g., the 
number of people that face a cancer risk exceeding 100 in 1 million), 
or the estimated number of additional cancer cases each year. 

Source: GAO analysis of EPA documents. 

Notes: EPA maintains information used in the hazard identification and 
dose-response assessment stages of risk assessments in its Integrated 
Risk Information System (IRIS) database. 

Lifetime excess cancer risk refers to the estimated additional risk of 
developing cancer that a person would have if exposed to a specific 
concentration of an air toxic 24 hours a day, 7 days a week, for 70 
years. 

[End of table] 

The risk assessment process is limited by scientific uncertainty about 
the health effects associated with exposure to air toxics. Nonetheless, 
the Clean Air Act's residual risk program seeks to determine whether 
the most exposed individuals face excess cancer risk of more than 1 in 
1 million. In cases where estimated risks exceed this threshold, EPA 
develops a residual risk standard that seeks to provide an ample margin 
of safety for affected individuals.[Footnote 12] Figure 2 provides an 
overview of the regulatory process for major stationary sources of air 
toxics, including MACT standards and 8-year technology and residual 
risk reviews. 

Figure 2: EPA Air Toxics Regulatory Framework for Major Stationary 
Sources: 

[See PDF for image] 

Source: GAO. 

[End of figure] 

In addition to requirements for major sources, the act required EPA to 
develop a comprehensive strategy to control emissions of air toxics in 
urban areas, including identifying at least 30 small stationary source 
categories that account for 90 percent of the risk from these sources, 
and issue regulations by November 2000. EPA has listed 70 small 
stationary source categories for regulation. The act also required EPA 
to assess the need for and feasibility of air toxics standards for 
motor vehicles and fuels, and, based on that assessment, issue 
regulations to control air toxics from motor vehicles and fuels. 

Table 3 summarizes the 453 actions required of EPA under the air toxics 
provisions of the 1990 amendments. Because these actions range in scope 
from developing MACT standards to issuing reports, they vary in their 
potential to reduce emissions. 

Table 3: Number of Air Toxics Actions Required under the 1990 Clean Air 
Act Amendments: 

Air toxics category: Major stationary sources regulated by MACT 
standards; 
Number of actions required: 158. 

Air toxics category: 8-year residual risk reviews for MACT standards; 
Number of actions required: 96. 

Air toxics category: 8-year technology reviews for MACT standards; 
Number of actions required: 96. 

Air toxics category: Standards for small stationary sources; 
Number of actions required: 70. 

Air toxics category: Mobile sources; 
Number of actions required: 2. 

Air toxics category: Other (reports, studies, etc.); 
Number of actions required: 31. 

Air toxics category: Total; 
Number of actions required: 453. 

Source: GAO analysis of EPA documents. 

Note: The act required EPA to list major and small source categories of 
the listed hazardous air pollutants (currently 187 chemicals). In 
response, EPA identified 158 major source categories and was required 
to issue a standard for each category. EPA responded by issuing 96 
different standards, some of which apply to multiple source categories. 
The 8-year residual risk and technology reviews apply to the 96 
standards, which accounts for the difference between the 158 
requirements to regulate major sources and the 96 requirements each for 
residual risk and technology reviews. 

[End of table] 

EPA's Office of Air and Radiation has primary responsibility for 
completing air toxics actions required under the Clean Air Act. Within 
the Office of Air and Radiation, responsibility for implementing the 
air toxics requirements of the Act rests primarily with the Office of 
Air Quality Planning and Standards and, to a lesser extent, with the 
Office of Transportation and Air Quality. The responsibility for 
analyzing the health, economic, and other effects of individual air 
toxics programs also rests with these offices. The Office of Policy 
Analysis and Review supplements these program-specific analyses by 
conducting periodic assessments of the health, ecological, and economic 
effects of the overall Clean Air Act, including the air toxics 
provisions, and coordinating these studies as appropriate with other 
EPA offices. In conducting these broader studies, the Office of Policy 
Analysis and Review also works with the Advisory Council for Clean Air 
Act Compliance Analysis, an independent, multi-disciplinary panel of 
outside experts organized under the auspices of EPA's Science Advisory 
Board. The agency's Office of Research and Development performs 
scientific research on air toxics to support regulatory efforts. The 
Office of Enforcement and Compliance Assurance directs efforts to 
ensure compliance with air toxics requirements. In most cases, state 
and local air pollution control agencies implement the standards 
developed by EPA. Additionally, the act generally allows these agencies 
to impose more stringent requirements than the federal standards, 
although some states have enacted laws or rules prohibiting air 
pollution control agencies from adopting more stringent requirements. 
Nonetheless, some state and local programs have developed innovative 
air toxics programs. 

EPA Has Made Limited Progress in Addressing the Clean Air Act's 
Requirements for Air Toxics and Faces Significant Implementation 
Challenges: 

EPA has completed issuing emissions standards for major stationary 
sources but issued most of these standards late and has made limited 
progress toward completing the remaining air toxics requirements. In 
particular, EPA has made little progress and is behind schedule in 
completing residual risk and technology reviews and in issuing 
emissions standards for small stationary sources and mobile sources. 
EPA's limited progress and program implementation challenges have 
resulted primarily from the program's lower priority relative to other 
clean air programs. Furthermore, the agency lacks a program 
implementation strategy. Stakeholders we interviewed--including EPA, 
state and local agency officials, environmental groups, and industry 
representatives--provided additional perspective on EPA's 
implementation of the air toxics program and highlighted data 
limitations and inadequate funding as major challenges. 

EPA Issued Most of the MACT Standards behind Schedule and Has Made 
Limited Progress in Completing the Other Air Toxics Requirements: 

EPA has completed issuing the MACT standards for major stationary 
sources but has made limited progress in addressing requirements 
related to residual risk and technology reviews, and in issuing 
standards for small stationary sources and mobile sources. As a result 
of the limited progress in implementing these requirements, EPA has not 
reduced human health risks from air toxics to the extent and in the 
time frames envisioned in the act. Table 4 summarizes EPA's overall 
progress in implementing air toxics requirements under the Clean Air 
Act. 

Table 4: EPA Progress in Meeting Air Toxics Requirements: 

Issue MACT emission standards for major source categories; 
Number of requirements: 158; 
Requirements met: Met on time[A]: 4; 
Requirements met: Met late: 154; 
Requirements unmet: Unmet-- past due: 0; 
Requirements unmet: Unmet--not yet due: 0. 

Residual risk reviews; 
Number of requirements: 96; 
Requirements met: Met on time[A]: 0; 
Requirements met: Met late: 5; 
Requirements unmet: Unmet--past due: 16; 
Requirements unmet: Unmet--not yet due: 75. 

Control technology reviews; 
Number of requirements: 96; 
Requirements met: Met on time[A]: 0; 
Requirements met: Met late: 5; 
Requirements unmet: Unmet--past due: 16; 
Requirements unmet: Unmet--not yet due: 75. 

Small stationary sources; 
Number of requirements: 70; 
Requirements met: Met on time[A]: 0; 
Requirements met: Met late: 16; 
Requirements unmet: Unmet--past due: 54; 
Requirements unmet: Unmet--not yet due: 0. 

Mobile sources; 
Number of requirements: 2; 
Requirements met: Met on time[A]: 0; 
Requirements met: Met late: 1; 
Requirements unmet: Unmet--past due: 1; 
Requirements unmet: Unmet--not yet due: 0. 

Other; 
Number of requirements: 31; 
Requirements met: Met on time[A]: 8; 
Requirements met: Met late: 21; 
Requirements unmet: Unmet--past due: 2[B]; 
Requirements unmet: Unmet--not yet due: 0. 

Total; 
Number of requirements: 453; 
Requirements met: Met on time[A]: 12; 
Requirements met: Met late: 202; 
Requirements unmet: Unmet--past due: 89; 
Requirements unmet: Unmet--not yet due: 150. 

Source: GAO analysis of EPA documents. 

Notes: This analysis reflects the status of the requirements as of 
April 2006. 

[A] We count requirements met by EPA that did not have deadlines 
specified in the act as on time. 

[B] EPA is required to periodically review the list of air toxics 
established by the act but has not yet done so. This requirement was 
not accompanied by a deadline. Based on other time frames required by 
the act, we list this requirement as unmet/past due instead of unmet/ 
not yet due. 

[End of table] 

To meet the act's requirements for major stationary sources, EPA had to 
identify a list of major source categories and then issue standards 
beginning in 1992, with all standards due by November 2000. In 
response, EPA identified 158 major source categories and issued 96 
standards covering these categories between 1993 and 2004. Table 5 
summarizes the timeliness of EPA's MACT standards relative to the act's 
deadlines. While the agency missed most of the deadlines, a senior EPA 
official said that issuing the 96 standards represented a major 
achievement and that the agency had never previously issued so many 
standards for one program in such a limited period of time. 

Table 5: Timeliness of MACT Emission Control Standards for Major Source 
Categories: 

Issue MACT emission standards for major source categories; 
Number of requirements: 158; 
Requirements met according to the schedule specified in the Clean Air 
Act: On time or early: 4; 
Requirements met according to the schedule specified in the Clean Air 
Act: 0-1 years late: 23; 
Requirements met according to the schedule specified in the Clean Air 
Act: 1-2 years late: 68; 
Requirements met according to the schedule specified in the Clean Air 
Act: More than 2 years late: 63. 

Source: GAO analysis. 

Note: This analysis reflects the status of the requirements as of April 
2006. 

[End of table] 

Because EPA issued most of the MACT standards well behind schedule, the 
residual risk and control technology reviews, which EPA is to complete 
8 years after issuing each standard, have been pushed back 
commensurately, thereby delaying any additional public health 
protection that these reviews may provide. Specifically, instead of 
completing the initial residual risk assessments and technology reviews 
for all of the MACT standards by 2008 as specified by the act, EPA is 
not required to complete all of the initial reviews until 2012 because 
it issued many MACT standards behind schedule. For example, because EPA 
issued the MACT standard for industrial boilers in 2004 rather than 
2000, as required, the residual risk assessment and technology review 
for this source category become due in 2012, almost 4 years later than 
the act's intended timeline. Furthermore, EPA is behind schedule on the 
residual risk assessments and technology reviews. As of April 2006, EPA 
had finalized only five of these reviews, and all of these were late. 
Three additional reviews have court-ordered deadlines and will be 
completed by the end of 2006, according to EPA. 

The act required EPA to develop regulations for small stationary 
sources by November 2000.[Footnote 13] However, the agency has not met 
this schedule. In July 2000, EPA outlined its plans for issuing 
standards for small stationary sources in a report to Congress 
describing its strategy for reducing threats from air toxics in urban 
areas.[Footnote 14] This report identified 16 categories of small 
stationary sources that it described as "already subject to regulation" 
or "will be subject to regulation." The report also identified 13 
additional categories for which it planned to issue standards by 2004. 
In 2002, EPA expanded the list to include a total of 70 source 
categories. However, as of April 2006, EPA has issued standards for 
only 16 categories of sources, leaving standards for 54 source 
categories past due. Furthermore, the agency faces court-ordered 
deadlines to complete standards for all of the remaining categories of 
small stationary sources by June 15, 2009. 

The act also required EPA to study the need and feasibility of air 
toxics standards for motor vehicles and fuels and, based on the study, 
develop a regulation to control air toxics from motor vehicles and 
fuels by 1995. EPA completed the study in 1993 (about 11 months after 
the deadline) and, after missing the 1995 deadline for the regulation, 
faced a court-ordered consent decree to complete the regulation by 
2001. To comply, EPA issued an initial rule in 2001 that stated that a 
second and final rule making would follow in 2004.[Footnote 15] The 
agency missed this deadline and eventually proposed a second rule in 
February 2006, with a final rule planned for February 2007.[Footnote 
16] The proposed rule would limit the benzene content of gasoline and 
reduce toxic emissions from passenger vehicles and gas cans according 
to EPA. 

Finally, the act contained 31 requirements that do not fit into the 
categories discussed above, including reports to Congress and guidance 
for state and local programs. As of April 2006, EPA has met 29 of these 
requirements. One of the key areas where EPA has not taken action 
relates to the act's requirement for the agency to periodically review 
and update, as appropriate, the list of air toxics. Officials 
responsible for the program said the agency does not proactively 
conduct such reviews and instead has adopted a reactive approach, 
whereby the agency responds to petitions filed by external stakeholders 
seeking to add or delete chemicals. EPA officials, citing insufficient 
resources to develop a more proactive approach, said that their efforts 
have focused on reviewing petitions for additions and deletions filed 
by external stakeholders. 

Since 1990, EPA has received one petition to list a new air toxic 
(diesel exhaust) and seven petitions to delist. The petition to list 
diesel exhaust is under review, and of the seven petitions to delist, 
three have been granted, two have been denied, and two are under 
review, according to EPA. Overall, EPA has not added any new chemicals 
to the list of regulated pollutants, but three chemicals and several 
substances from a listed group of chemicals have been removed. The 
agency's consideration of diesel exhaust in response to an 
environmental group's petition has taken more than 2 years, resulting 
in a lawsuit when the agency did not complete its review within 18 
months, as required by the act. EPA and the environmental group reached 
an agreement in February 2006 that requires the agency to decide by 
June 2006 whether to list diesel exhaust as an air toxic. 

A 2004 report by the National Academies highlighted EPA's lack of a 
process for reviewing new pollutants despite the estimated 300 
chemicals that enter commerce each year. The report recommended that 
EPA "establish a more dynamic process for considering new pollutants." 
To date, EPA has not addressed this recommendation, according to senior 
agency officials. Furthermore, a 2004 study published in the Journal of 
the Air & Waste Management Association screened 1,086 chemicals for 
potential addition to the list of regulated air toxics and found that 
44 merited further consideration for addition to the list based on 
available toxicity and emissions data. 

Senior EPA air program officials said the agency's progress in meeting 
the act's air toxics requirements should be viewed within the context 
of limited funding for clean air programs and the agency's need to 
focus its resources on the areas where it expects the greatest health- 
risk reductions. Scientific information on the health effects of air 
toxics is less comprehensive than that available for higher-priority 
clean air programs, such as those targeting smog and particulate 
matter. Additionally, several officials said that other regulatory and 
voluntary programs limit emissions of air toxics as a side 
benefit.[Footnote 17] 

EPA Faces Implementation Challenges and Lacks an Overall Management 
Strategy: 

EPA considers the air toxics program a lower priority than its three 
other major clean air programs--including those to address criteria 
pollutants, international environmental issues such as climate change, 
and indoor air quality issues such as exposure to radon gas--because 
senior officials in EPA's Office of Air and Radiation believe these 
programs have more potential to reduce health risks. As shown in table 
6, the percentage of funding for air toxics relative to all clean air 
programs ranged from 18 percent to 19 percent between 2000 and 2003, 
but declined to 15 percent in 2004 and 12 percent in 2005. However, the 
total dollar amounts (in inflation-adjusted 2005 dollars) devoted to 
air toxics increased each year between 2000 and 2004, with a decline in 
2005. 

Table 6: EPA Funding for Air Toxics Program as a Percentage of Funding 
for All Clean Air Programs, Fiscal Years 2000 through 2005: 

Thousands of dollars. 

Fiscal year: 2000; 
Funding for air toxics program: 106,475; 
Funding for all clean air programs: 605,574; 
Funding for air toxics program as a percentage of all clean air 
programs: 18. 

Fiscal year: 2001; 
Funding for air toxics program: 118,331; 
Funding for all clean air programs: 640,056; 
Funding for air toxics program as a percentage of all clean air 
programs: 18. 

Fiscal year: 2002; 
Funding for air toxics program: 121,668; 
Funding for all clean air programs: 636,851; 
Funding for air toxics program as a percentage of all clean air 
programs: 19. 

Fiscal year: 2003; 
Funding for air toxics program: 122,118; 
Funding for all clean air programs: 641,514; 
Funding for air toxics program as a percentage of all clean air 
programs: 19. 

Fiscal year: 2004; 
Funding for air toxics program: 143,575; 
Funding for all clean air programs: 936,286; 
Funding for air toxics program as a percentage of all clean air 
programs: 15. 

Fiscal year: 2005; 
Funding for air toxics program: 112,986; 
Funding for all clean air programs: 909,219; 
Funding for air toxics program as a percentage of all clean air 
programs: 12. 

Source: GAO analysis of EPA data. 

Note: Dollar amounts are in inflation-adjusted 2005 dollars. 

[End of table] 

Within the air toxics program, EPA's initial priority was to complete 
the MACT standards because the agency believed that this aspect of the 
program had the greatest potential to address risks from air toxics. 
Despite EPA placing a priority on issuing the MACT standards, the 
agency still fell behind schedule when it missed deadlines for the 
first round of standards (due in 1992) and has never caught up to the 
act's implementation schedule. EPA officials said they missed some of 
the MACT deadlines because of technical challenges, including a lack of 
emissions data from affected source categories and the complexity of 
many of the regulated facilities. The missed deadlines led to lawsuits 
filed by external parties seeking compliance with the act's 
implementation schedule, resulting in court-ordered deadlines for the 
agency to complete standards. Furthermore, senior EPA officials said 
these court-ordered deadlines largely drive the program's agenda. In 
this way, EPA ceded control of the priority-setting process, and this 
problem is still evident. For example, a senior official responsible 
for the development of regulations said that the agency's highest 
priority for the remaining requirements is addressing residual risk 
reviews and small stationary source standards with court-ordered 
deadlines. 

The lower priority of the air toxics program in general and the 
priority given to MACT standards within the program, as well as 
technical challenges, have caused delays in completing the residual 
risk and technology reviews, as well as standards for small stationary 
and mobile sources. Further, as shown in table 7, available EPA data 
indicate that small stationary and mobile sources in total have 
accounted for more emissions than major stationary sources in every 
emissions inventory completed since the 1990 amendments. Furthermore, 
the agency has estimated that benzene--a known carcinogen emitted 
primarily by mobile sources--accounts for about 25 percent of the 
cancer risk posed by air toxics across the nation. Benzene is also the 
only air toxic that, to date, EPA has determined poses sufficient risks 
to qualify as a "national cancer risk driver."[Footnote 18] 

Table 7: Percentage of Estimated Total Air Toxics Emissions by Source 
Type, 1993, 1999, and 2002: 

Percent. 

2002; 
Estimated total emissions (million tons): 4.6; 
Mobile sources: 41; 
Small stationary sources: 30; 
Major stationary sources: 20; 
Other: 9. 

1999; 
Estimated total emissions (million tons): 5.1; 
Mobile sources: 43; 
Small stationary sources: 25; 
Major stationary sources: 25; 
Other: 6. 

1993; 
Estimated total emissions (million tons): 7.1; 
Mobile sources: 46; 
Small stationary sources: 24; 
Major stationary sources: 27; 
Other: 3. 

Source: GAO analysis of EPA data. 

Note: Totals may not add to 100 percent due to rounding. 

[End of table] 

EPA developed air toxics emission inventories for 1993, 1996, 1999, and 
2002. A large part of the 1993 baseline inventory is based on data 
obtained from 1990. For simplicity, and because EPA has traditionally 
referred to it as such, we refer to this data as the 1993 baseline 
inventory. EPA said it did not provide data for 1996 because the agency 
has not updated the information from that year for consistency with the 
methodology used for the 1993, 1999, and 2002 data. 

EPA expects that the proposed mobile source air toxics rule will reduce 
benzene emissions. In addition, a senior EPA air program official said 
that other regulations for mobile sources, including standards that 
affect gasoline formulations as well as programs addressing emissions 
from diesel engines, will also reduce emissions of air toxics as a side 
benefit. Nonetheless, mobile sources will continue to represent an area 
of significant opportunity to reduce emissions and related human health 
risks. 

Addressing the remaining requirements for residual risk standards and 
small stationary sources will require overcoming significant technical 
challenges. Regarding residual risk standards, the Clean Air Act's 
requirement that EPA introduce a risk element into the regulatory 
decision-making process marks a departure from the approach the act 
used with MACT standards, which generally did not require EPA to take 
the inherent toxicity or health risks from pollutants into account. EPA 
officials said that conducting the residual risk assessments requires a 
large amount of data, much of which is difficult to obtain. For 
example, to adequately assess the human health risk posed by a 
particular source, EPA needs data on the health effects associated with 
each pollutant, the location of sources, distances between sources and 
affected populations, and the concentrations of emissions at different 
distances from facilities. 

Challenges in regulating small stationary sources center on difficulty 
in characterizing the large number of widely dispersed facilities such 
as industrial boilers, paint-stripping operations, and auto-body shops. 
In some cases, data do not exist on the number or location of 
facilities potentially subject to a regulation. Furthermore, unlike the 
large stationary sources affected by MACT standards, owners and 
operators of these sources have limited resources to implement 
regulations and will require extensive outreach and compliance 
assistance. 

EPA's challenges in meeting the act's remaining requirements are 
exacerbated by the lack of a management plan that identifies priorities 
and necessary resources. The agency's overall strategic plan outlines 
the goals and targets for emissions and risk reduction across all clean 
air programs but does not specify priorities or necessary levels of 
funding for the air toxics program. Similarly, the agency's budget 
requests provide limited information on the agency's air toxic program 
activities or priorities. Furthermore, a senior EPA official said that 
the agency has not estimated how much funding the air toxics program 
needs to meet the act's remaining requirements. Such information could 
assist Congress in making its appropriations decisions, enhance the 
program's transparency to the public, and guide the agency in 
implementing the program. 

Key Program Stakeholders Provided Further Insights on EPA's 
Implementation Challenges: 

To better understand the challenges facing EPA's air toxics program, we 
interviewed various stakeholders, including officials from EPA, 
industry and environmental groups, and state and local air pollution 
control agencies.[Footnote 19] Each respondent rated the extent to 
which nine specific issues posed a challenge to EPA in implementing the 
air toxics program, and we then averaged the responses within each 
stakeholder group. As shown, in table 8, the average response within 
each group identified at least one of seven different issues as a 
challenge to a large or very great extent.[Footnote 20] Although 
perceptions varied among the stakeholder groups, three issues emerged 
as primary challenges--the availability of reliable data to assess the 
benefits of regulating air toxics, the adequacy of program funding, and 
the program's low priority relative to other clean air programs. As 
shown in the table, respondents from at least three of the four 
stakeholder groups we interviewed identified each of these challenges 
as significant. 

Table 8: Issues Rated by Stakeholders as Challenges to a Large or Great 
Extent: 

Challenges: Availability of reliable data to assess benefits of 
regulating hazardous air pollutants; 
Stakeholder groups: EPA: check; 
Stakeholder groups: Industry: check; 
Stakeholder groups: Environmental: [Empty]; 
Stakeholder groups: State and local: check. 

Challenges: Adequacy of program funding;  
Stakeholder groups: EPA: check; 
Stakeholder groups: Industry: [Empty]; 
Stakeholder groups: Environmental: check; 
Stakeholder groups: State and local: check. 

Challenges: Priority of program relative to other air programs; 
Stakeholder groups: EPA: check; 
Stakeholder groups: Industry: [Empty]; 
Stakeholder groups: Environmental: check; 
Stakeholder groups: State and local: check. 

Challenges: Number of Clean Air Act requirements pertaining to 
hazardous air pollutants; 
Stakeholder groups: EPA: check; 
Stakeholder groups: Industry: check; 
Stakeholder groups: Environmental: [Empty]; 
Stakeholder groups: State and local: [Empty]. 

Challenges: Adequacy of resources at the state, local, and tribal 
levels to implement regulations; 
Stakeholder groups: EPA: check; 
Stakeholder groups: Industry: [Empty]; 
Stakeholder groups: Environmental: [Empty]; 
Stakeholder groups: State and local: check. 

Challenges: Strain on resources due to litigation; 
Stakeholder groups: EPA: check; 
Stakeholder groups: Industry: [Empty]; 
Stakeholder groups: Environmental: [Empty]; 
Stakeholder groups: State and local: [Empty. 

Challenges: Availability of reliable data on sources and their 
emissions; 
Stakeholder groups: EPA: [Empty]; 
Stakeholder groups: Industry: [Empty]; 
Stakeholder groups: Environmental: check; 
Stakeholder groups: State and local: [Empty].  

Source: GAO. 

[End of table] 

Several stakeholders identified linkages among the three primary 
challenges. For example, some stakeholders said that the problems with 
limited resources stemmed from the program's low priority. In addition, 
some stakeholders said that the lack of information on the benefits of 
regulating air toxics reinforced the program's low priority because the 
agency cannot demonstrate the results it achieves through investments 
in the program. 

In addition, industry and EPA stakeholders cited the number of air 
toxics requirements as a challenge to a large or very great extent. 
Respondents from both groups stated that the agency has insufficient 
resources to meet such a large number of requirements in the specified 
time frames. Industry officials noted that the number of requirements 
was unrealistic, and some EPA stakeholders said that Congress did not 
understand the number of emissions sources involved or the level of 
effort required to write standards. EPA and state and local 
stakeholders also cited the adequacy of resources at the state, local, 
and tribal levels to implement regulations as a significant challenge. 

Available Information on Costs and Benefits Is Not Sufficient to 
Measure the Program's Effectiveness: 

The information available on the costs and benefits of EPA's air toxics 
program is not sufficiently comprehensive to measure the overall 
effectiveness of the program. For example, because of limited data, 
EPA's major economic assessments of the Clean Air Act have not included 
monetized estimates of the program's benefits, such as reduced 
incidence of cancer, and have provided only limited information on 
costs. The absence of information on benefits stems from a lack of data 
on the extent to which incremental reductions in exposure to air toxics 
affect an average person's chance of developing adverse health effects. 
The agency also lacks reliable data on the quantities of each pollutant 
emitted prior to the adoption of air toxics regulations or in the years 
thereafter. Furthermore, other potential indicators of the program's 
effectiveness, such as data on compliance with air toxics regulations, 
are inconclusive. As a result, it is difficult to compare the results 
of investments in the air toxics program with those generated by clean 
air programs on which EPA has placed a higher priority. 

EPA's Assessments of the Clean Air Act Have Not Estimated the Economic 
Benefits of the Air Toxics Program: 

Although EPA has conducted two major assessments of the costs and 
benefits of its programs under the Clean Air Act, the agency has not 
fully analyzed the air toxics program primarily because of difficulty 
in characterizing the program's effects on public health.[Footnote 21] 
Without a comprehensive assessment of costs and benefits, it is 
difficult to gauge the program's cost effectiveness or net benefits 
(total benefits minus total costs) or compare these effects with those 
of higher-priority air pollution control programs. 

The two assessments of the act's costs and benefits focused on separate 
time periods. EPA refers to the first assessment, completed in 1997, as 
the "retrospective" analysis because it covered the period 1970 to 
1990. It is of limited use in understanding the economic effects of the 
current air toxics program because this time period predates the 
significant expansion of the program after the 1990 amendments. 

The second analysis, completed in 1999, is referred to as the 
"prospective" analysis because it covered the period 1990 to 2010. This 
study attempted to forecast the future economic impacts of the 1990 
amendments and estimated that the overall net benefits of clean air 
regulations from 1990 to 2010 would total $510 billion (1990 dollars), 
with a benefit-to-cost ratio of four to one. Most (over 90 percent) of 
the monetized benefits included in the analysis stemmed from reduced 
incidence of health effects associated with exposure to five of the six 
criteria pollutants--carbon monoxide, ground-level ozone, particulate 
matter, nitrogen oxides, and sulfur dioxide. EPA places the highest 
priority within its clean air programs on the criteria pollutants. 

The prospective analysis is of limited use in understanding the effects 
of the air toxics program because it provided incomplete information on 
the costs of air toxics standards and did not include estimates of the 
human health or other benefits of these standards. Specifically, the 
cost estimates reflect only the 21 standards EPA had issued at the time 
of the study--a number that has since grown to 96. EPA estimated that 
the cost to industry of complying with these 21 MACT standards would 
total $780 million in 2000 and rise to $840 million by 2010. According 
to EPA, these estimates primarily reflect the cost of purchasing, 
operating, and maintaining pollution control equipment. As shown in 
table 9, these costs represent a relatively small fraction of the total 
estimated costs of the 1990 amendments over that time period. 

Table 9: Summary of Annual Costs Imposed by the 1990 Clean Air Act 
Amendments: 

Dollars (in millions). 

Programs: Title I--Ambient air quality standards; 
Costs in 2000: $8,600; 
Percentage of total costs: 44; 
Costs in 2010: $14,500; 
Percentage of total costs: 54. 

Programs: Title II--Mobile sources; 
Costs in 2000: 7,400; 
Percentage of total costs: 38; 
Costs in 2010: 9,050; 
Percentage of total costs: 34. 

Programs: Title III--Air toxics; 
Costs in 2000: 780; 
Percentage of total costs: 4; 
Costs in 2010: 840; 
Percentage of total costs: 3. 

Programs: Title IV--Acid rain; 
Costs in 2000: 2,300; 
Percentage of total costs: 12; 
Costs in 2010: 2,040; 
Percentage of total costs: 8. 

Programs: Title V--Permitting; 
Costs in 2000: 300; 
Percentage of total costs: 2; 
Costs in 2010: 300; 
Percentage of total costs: 1. 

Programs: Total annual costs; 
Costs in 2000: $19,400; 
Percentage of total costs: 100;
Costs in 2010: $26,800; 
Percentage of total costs: 100.  

Source: EPA. 

Note: Dollar Amounts are in 1990 dollars. 

[End of table]

An EPA official responsible for the prospective study said that the 
agency did not include estimates for the aspects of the program that it 
had not yet implemented--such as the 75 remaining MACT standards-- 
because, at the time, the agency did not have information on the number 
of facilities that would have to comply with future standards or the 
level of emissions control the standards would require. Without this 
information, the official said it was appropriate to exclude these 
future standards from the analysis. Nonetheless, EPA acknowledged the 
lack of information on the costs of future air toxics standards as a 
key uncertainty of the analysis.[Footnote 22] 

EPA plans to update its cost estimates as part of a new prospective 
analysis covering 1990 to 2020. The revised cost estimates will include 
all of the completed MACT standards as well as any other air toxics 
rules issued by September 2005 (except the residual risk rule for coke 
ovens, which entails emissions reductions and compliance costs that 
would have a negligible effect on the overall analysis). An EPA 
official responsible for the analysis said the agency expects to have 
preliminary results of the revised cost estimates in late 2006, with a 
final report expected in 2007. 

EPA Lacks Key Data Needed to Estimate the Benefits of Air Toxics 
Regulations: 

The prospective analysis of the 1990 Clean Air Act amendments did not 
include monetized estimates of the benefits of air toxics regulations, 
such as decreased cancer risks to affected individuals, because the 
agency did not have sufficient data to estimate these effects. As shown 
in table 10, estimating the benefits of EPA's air toxics program 
requires a substantial amount of scientific data. Specifically, this 
process involves determining the extent to which reductions in exposure 
to air toxics have decreased the incidence of adverse health effects, 
including cancer and noncancer illnesses. This, in turn, requires 
estimating the extent of adverse health effects stemming from exposure 
to air toxics both before (see steps 1 to 3 below) and after (see steps 
4 to 6 below) adopting air toxics regulations. For example, exposure to 
air toxics prior to the adoption of a regulation may have caused 1,000 
cases of cancer per year but the presence of a regulation may have 
decreased this number to 500 cases per year. The 500 avoided cases 
would represent a key health benefit of the regulation. The final step 
of the process (step 7) involves assigning dollar values to these 
health benefits. 

Table 10: Key Steps in Estimating the Benefits of Controlling Air 
Toxics: 

Step: 1; 
Task: Characterize the relationship between pollutants and the adverse 
health effects associated with exposure to these pollutants (referred 
to as "dose-response" relationships); 
Data requirements: Information on cancer and noncancer effects of 187 
different pollutants, as well as on how incremental decreases in 
exposure to these pollutants affect the incidence of each adverse 
health effect. 

Step: 2; 
Task: Determine the baseline level of human exposure to pollutants in 
the absence of air toxics regulations; 
Data requirements: Information on concentrations of each pollutant in 
the ambient air prior to adoption of air toxics regulations, and on 
human exposures to these pollutants. This requires information on the 
amount of each pollutant emitted prior to the regulations, as well as 
computer models that calculate human exposures based on emissions data 
and other key variables such as meteorological conditions. 

Step: 3; 
Task: Use data from steps 1 and 2 above to determine the number of 
cases of each adverse health effect in the absence of regulations; 
Data requirements: No additional data required. 

Step: 4; 
Task: Determine level of human exposure to pollutants after the 
regulation. This involves estimating the extent to which the regulation 
has decreased emissions of each pollutant and related human exposures; 
Data requirements: Information on the amount of each pollutant emitted 
after adopting air toxics regulations, and computer models used in step 
2 to estimate the remaining level of exposure to each pollutant. 

Step: 5; 
Task: Calculate the remaining incidence of each health effect after 
implementing the regulation; 
Data requirements: Same as step 3; no additional data required. 

Step: 6; 
Task: Determine the number of cases of each health effect avoided as a 
result of the regulation by subtracting the number of remaining cases 
of adverse health effects (identified in step 5) from the number of 
baseline cases prior to the regulation (identified in step 3); 
Data requirements: No additional data required. 

Step: 7; 
Task: Assign dollar values to the number of avoided cases identified in 
step 6; 
Data requirements: Economic studies on the value of reducing incidence 
of cancer and noncancer health effects. 

Source: GAO analysis of EPA data. 

[End of table] 

Two primary factors limit EPA's ability to estimate the benefits of air 
toxics regulations. First, EPA lacks adequate information on the extent 
to which incremental reductions in exposure affect an average person's 
chance of developing adverse health effects. The limited information on 
these "dose-response" relationships represents the greatest challenge 
for the agency in conducting a benefits assessment for the air toxics 
program, according to a senior EPA official responsible for the 
retrospective and prospective analyses. A senior EPA official 
responsible for risk analysis drew a distinction between the type of 
data needed for a risk assessment, which often involves extrapolation 
from studies involving laboratory animals, and the type of data that 
economists need for a benefits assessment, which generally requires 
studies of human exposures. The official said that EPA currently has 
sufficient toxicological data, primarily from animal studies, to assess 
risks from 133 of the 187 air toxics. However, the official said the 
agency only has the type of dose-response data needed to estimate the 
economic benefits for a handful of pollutants.[Footnote 23] 

Second, EPA lacks reliable information on the quantities of each 
pollutant emitted prior to the adoption of air toxics regulations or in 
the years after adopting the regulations. EPA has tracked emissions of 
air toxics since 1993 and prepares a National Emissions Inventory every 
3 years. In 2006, EPA completed its most recent inventory, which has 
information on emissions in 2002. While the inventory represents the 
best available data on emissions of air toxics and is useful for 
identifying the relative contribution of emissions from different 
sources, a 2004 EPA Inspector General report identified shortcomings of 
the inventory that raise questions about its reliability and usefulness 
in measuring the effects of the air toxics program.[Footnote 24] For 
example, the report said that EPA cannot tell whether apparent 
reductions or increases in the inventory have resulted from changes in 
the way the agency estimated the inventory or from real reductions or 
increases in emissions. The report also cited problems with the limited 
involvement of state agencies in the development and validation of the 
inventory. 

Although the data in the emissions inventory are limited, EPA has used 
the emissions inventory and other available data to estimate human 
exposures to these pollutants. In 1999, EPA released its first National-
Scale Air Toxics Assessment (NATA), which relied on data from the 1996 
emissions inventory to estimate the potential health risks posed by air 
toxics in different geographic areas. EPA updated this analysis in 2006 
using data from the 1999 emissions inventory. While NATA is a useful 
indicator of potential health risks from air toxics at a given point in 
time, it is not useful as a measure of the agency's effectiveness in 
implementing the air toxics program because, according to EPA, the 
agency revised the number of stationary sources and pollutants included 
in its analysis. For example, the analysis based on the 1996 emissions 
inventory assessed risks from 33 pollutants, while the most recent 
analysis included 177 pollutants. As a result, EPA believes it is not 
meaningful to compare the results of the two assessments. 

Overall, the limited information on health outcomes associated with 
changes in exposure to air toxics hinders EPA's ability to quantify or 
monetize the economic benefits resulting from the air toxics program. 
In turn, this limits EPA's ability to develop monetized estimates of 
the program's net benefits or cost effectiveness. Such information 
would be useful not only for better understanding the economic effects 
of the air toxics program, but also for comparing the cost 
effectiveness of different air quality programs, which would help 
prioritize funding in addressing human health problems caused by air 
pollution. This information would also help EPA prioritize its 
remaining obligations under the 1990 amendments. In May 2002, EPA's 
Office of Research and Development (ORD) released a draft air toxics 
research strategy that discussed the agency's plans for improving 
information on dose-response relationships.[Footnote 25] In addition, 
ORD issued an air toxics plan in April 2003 that identified the 
shortcomings of existing dose-response data and plans for improving 
this information.[Footnote 26] In reviewing these documents, the 
agency's Science Advisory Board identified several concerns, including 
poor linkages across the two documents, inadequate research funding, 
and the need for a better research prioritization scheme.[Footnote 27] 

Other Indicators of the Program's Effectiveness Are Inconclusive: 

Without sufficient information to conduct a comprehensive cost-benefit 
analysis, EPA measures the effectiveness of its air toxics program 
based on estimated data from its emissions inventory. Specifically, EPA 
measures the changes in aggregate emissions (measured in tons per year) 
of all air toxics by comparing estimates from the most recent emissions 
inventory with the 1993 baseline inventory. While estimated emissions 
decreased by about 35 percent between 1993 and 2002 according to EPA, 
the data quality problems discussed above limit their usefulness in 
measuring the program's effectiveness. 

Two other problems also limit the usefulness of the emissions data as a 
performance measure. First, because pollutants differ substantially in 
their toxicity--small quantities of some chemicals pose greater risks 
than large quantities of less harmful chemicals--measuring changes in 
the total tons of all air toxics emitted does not necessarily provide a 
strong indication of the program's effectiveness in addressing health 
risks. The EPA Inspector General report discussed above recommended 
developing performance measures that address progress toward reductions 
in human exposure and health risk. Such measures would provide a better 
indication of changes in risks from air toxics. In the justification 
for its proposed fiscal year 2007 budget, EPA said that it was 
developing a "toxicity-weighted" emissions measure for the program. 

Second, EPA's practice of measuring the air toxics program's 
performance using estimated aggregate emissions data may not accurately 
measure the effect that the program has had on changes in emissions. 
The current performance measure attributes all changes in emissions to 
the federal air toxics program, but emissions may change for reasons 
unrelated to the agency's regulations. Some decreases in emissions may 
reflect cases where state and local air pollution control agencies have 
issued rules to control emissions that go beyond the federal 
regulations. As discussed in the next section of this report, some 
states set more stringent standards than EPA. On the other hand, a 
senior EPA official responsible for the economic analysis of air 
pollution regulations said that the agency may actually underestimate 
the program's effect. The official said that because of economic growth 
and related increases in industrial production over time, emissions 
would far exceed the current levels without the existing EPA air toxics 
regulations. 

We also evaluated two other potential indicators of the program's 
effectiveness--data on levels of air toxics in the ambient air and 
information on the degree of compliance with clean air regulations--to 
determine their usefulness as indicators of the program's 
effectiveness. While both could eventually serve as useful performance 
indicators, the available data are currently limited and inconclusive. 
Regarding data on ambient levels of air toxics, EPA has a monitoring 
network that includes 22 locations nationwide. The monitors generally 
track ambient levels of six priority air toxics that EPA believes pose 
a concern in all geographic areas of the United States.[Footnote 28] 

A 2005 EPA Inspector General report found shortcomings of the 
monitoring network, including limited monitoring in areas with the 
highest estimated cancer risks from air toxics as well as 
inconsistencies in the operation of the monitors.[Footnote 29] In 
responding to the report, EPA said that the Inspector General's 
concerns generally aligned with the agency's monitoring improvement 
efforts. It is currently unclear whether the existing monitoring data 
are representative or reliable indicators of the program's 
effectiveness. Nonetheless, ambient monitoring is a valuable component 
of the air toxics program and could eventually serve as a useful 
performance measure. It is also important to note that, while not part 
of the national monitoring network, a number of state and local 
agencies conduct their own air toxics monitoring. 

Finally, we reviewed available information on the degree of compliance 
with air toxics standards identified through evaluations of regulated 
facilities conducted by federal and state enforcement officials. As 
shown in table 11, inspectors have found most facilities in compliance 
with air toxics standards, with some degree of noncompliance at about 
one-quarter of all facilities. Compliance rates for these facilities 
may not represent the degree of compliance at all facilities because 
enforcement officials do not visit each facility every year and often 
target facilities where they suspect noncompliance.[Footnote 30] EPA 
enforcement officials said they do not currently have comprehensive 
data explaining the magnitude of the noncompliance in cases where 
inspectors found violations. For example, noncompliance could range 
from record-keeping problems to more serious violations, such as 
exceeding an emissions standard. Furthermore, it is important to note 
that, while EPA has completed issuing all of the MACT standards, 16 
standards have compliance dates after June 2006. Thus, information on 
compliance with these standards will not become available until after 
that time. 

Table 11: Results of Inspections at Facilities Regulated by Air Toxics 
Standards, 2003 and 2004: 

Year: 2004; 
Total facilities inspected: 731; 
Facilities in compliance (percentage of total): 483 (66); 
Facilities in noncompliance (percentage of total): 194 (27); 
Facilities with unknown compliance status (percentage of total): 54 
(7). 

Year: 2003; 
Total facilities inspected: 664; 
Facilities in compliance (percentage of total): 432 (65); 
Facilities in noncompliance (percentage of total): 174 (26); 
Facilities with unknown compliance status (percentage of total): 58 
(9). 

Source: GAO analysis of EPA data. 

[End of table] 

While the available enforcement data are limited, EPA has identified 
cases of significant noncompliance with air toxics regulations. 
Specifically, the agency has initiated a nationwide air toxics 
enforcement strategy to identify and correct noncompliance and achieve 
emissions reductions in targeted industry sectors. According to EPA, in 
2005, the agency took enforcement actions against facilities that 
failed to comply with targeted MACT standards which resulted in air 
toxics reductions of more than 160 tons and fines exceeding $600,000 
(2005 dollars). Furthermore, an official in EPA's Office of Enforcement 
and Compliance Assurance said that the agency achieved about 190 
additional tons of air toxics reductions in 2005 through enforcement 
actions that were not associated with the national air toxics 
enforcement strategy. 

State and Local Programs Employ Practices That Could Potentially Help 
EPA Enhance the Effectiveness of the Federal Air Toxics Program: 

State programs we reviewed in California, New Jersey, Oregon, and 
Wisconsin, and the local program we reviewed in Louisville, Kentucky, 
have air toxics programs that go beyond the federal program and employ 
practices that might help EPA enhance the effectiveness of its program. 
First, these programs address some public health risks that have not 
been addressed by the federal program. EPA could potentially strengthen 
its program by assessing and considering what states perceive as the 
primary gaps in the federal program. Second, the programs generally 
prioritize air toxics activities based on their risk reduction 
potential, which could serve as an example for EPA in prioritizing its 
remaining obligations under the act. Third, some of the programs 
conduct comprehensive risk assessments to identify the risk posed by 
all emissions from a facility, while EPA's residual risk program 
assesses risk in a more piecemeal and limited fashion. Fourth, several 
of the programs employ systematic approaches to identify and prioritize 
chemicals for addition to their lists of regulated air toxics, whereas 
EPA does not have such a process. Finally, the agencies stressed the 
importance of reliable data on emissions and chemical toxicity, and 
several programs have processes to better ensure the accuracy of 
emissions data submitted by regulated facilities. (See app. III for 
information on the key features of the state and local programs we 
reviewed.) 

Several State and Local Programs Address Gaps in EPA's Program: 

The five programs we reviewed address some public health risks that 
EPA's program does not. For example, the programs regulate smaller 
sources than EPA, set more stringent technology standards to control 
emissions, and include some large stationary sources that EPA does not 
address.[Footnote 31] In Wisconsin, any facility that emits one of 535 
air toxics in amounts that exceed certain thresholds may be subject to 
the state's air toxics program. In some cases, annual emissions of less 
than 1 pound per year from a facility could trigger the state rule, 
depending upon the toxicity of the chemical. Wisconsin officials said 
that they use lower thresholds than the Clean Air Act's 10-or 25-ton 
thresholds because even small emissions of very toxic chemicals can 
present risks to the public. Similarly, New Jersey officials said that 
their state program addresses smaller facilities than EPA because most 
of the numerous chemical facilities in the state are not subject to 
MACT standards since they do not emit air toxics at levels that exceed 
federal thresholds. In contrast, in accordance with the Clean Air Act, 
MACT standards for major sources and the corresponding residual risk 
reviews apply to facilities in 158 industries with emissions of 10 tons 
or more of a single air toxic or 25 tons or more of a mixture of the 
187 federal air toxics. 

In terms of the stringency of the technology standards used to limit 
emissions of air toxics, California and New Jersey officials said that 
the technology standards in their states were often more stringent than 
EPA's MACT standards. For example, California officials said that 
petroleum refineries in their state use more stringent control 
technologies, and they noted that EPA chose not to include these 
technologies as part of its survey of controls already in use when it 
developed the MACT standard for this industry. 

Regarding the types of facilities that are regulated by EPA, some state 
officials expressed concern that EPA did not develop MACT standards for 
some major stationary sources of air toxics in their states. For 
example, Oregon officials said that they requested EPA to issue MACT 
standards for several categories of sources, including ceiling tile 
manufacturing and titanium smelting if it found that they were major 
sources of air toxics. Oregon officials expressed concern with EPA's 
apparent lack of response to their request because these significant 
emitters of air toxics in Oregon do not fall into one of the 158 major 
source categories that EPA identified and regulates. Further, the State 
and Territorial Air Pollution Program Administrators and the 
Association of Local Air Pollution Control Officials (STAPPA/ALAPCO) 
has compiled a list of over 40 major emission source categories of air 
toxics that were not regulated by EPA MACT standards. While the five 
programs we reviewed would generally address such sources, similar 
sources would be unregulated in the states whose programs are based 
entirely on the federal program. Importantly, in a number of cases, 
state law limits the ability of state and local programs to go beyond 
federal requirements. For example, in 2002, STAPPA/ALAPCO found that 26 
states from every region in the country have precluded their state air 
pollution control agencies from imposing clean air requirements beyond 
those established by EPA. 

State and Local Programs Prioritize Their Actions Based on Risk 
Reduction Potential: 

The approaches some state and local agencies use to develop their air 
toxics programs differ from EPA's approach in that they direct 
resources to the areas of highest risk, whereas, given the Clean Air 
Act's prescribed schedule, EPA has primarily focused on regulating 
emissions from certain large stationary sources. In contrast, several 
state and local programs generally rely on monitoring (the measurement 
of air toxics in the ambient air) and modeling (estimating toxics in 
the air using computer models) to identify chemicals, geographic areas, 
or facilities of concern and develop measures to address these risks. 

The Oregon and Louisville, Kentucky, programs illustrate the use of 
risk-based prioritization. Oregon's air toxics program seeks to 
identify geographic areas of high risk through modeling and monitoring 
and to then concentrate resources on those areas. While not yet fully 
implemented, the program plans to conduct statewide modeling using its 
emissions inventory to identify areas of potential concern and then 
conduct monitoring to delineate geographic areas of high risk. 
According to program staff, the geographic approach is an efficient way 
to address risk because it is targeted and focuses on the greatest 
risks. Because public health risks from air toxics may vary depending 
on proximity to emissions sources and other factors, the practice of 
identifying areas of high risk and taking steps to address these risks 
shows promise as part of an overall risk reduction strategy. 

Similarly, Louisville created a program to address high health risks 
near an industrial complex and in the surrounding community that were 
identified through monitoring of pollutants in the ambient air. 
According to program officials, toxic emissions from a section of 
Louisville called "Rubbertown"--home to a complex of chemical 
facilities and other manufacturers--have been the subject of public 
concern since the 1940s. From 2000 through 2001, program officials 
worked with the University of Louisville, EPA, and other stakeholders 
to monitor the ambient air near Rubbertown and the surrounding 
community to assess the extent of the problem. A risk assessment based 
on the monitoring data determined that 18 chemicals posed an 
unacceptable risk to the public. Consequently, Louisville officials 
designed the program to target large emitters of these 18 chemicals 
before targeting smaller emitters of air toxics. 

In addition to some states' focus on identifying geographic areas or 
chemicals of concern, the state and local programs we reviewed use 
monitoring and modeling data to focus their efforts on specific 
facilities that pose risks to the public. For example, California 
requires certain large and small sources of air toxics to conduct 
facilitywide risk assessments using a standardized risk-screening 
model. If the modeling results show that risks exceed certain 
thresholds, the facility must conduct a more comprehensive risk 
assessment. This process allows California's state and local agencies 
to identify and focus on the sources that pose high risks to the 
public. In addition, Louisville and Wisconsin require certain sources 
to conduct facilitywide risk assessments as part of the permitting 
process.[Footnote 32] 

In contrast, several state and local officials said that EPA's program 
has not focused on the greatest risks. While EPA may have been driven 
by certain deadlines in the act, some state and local officials said 
that the agency has chosen to focus on certain large stationary sources 
even though EPA's data suggest that emissions from small stationary 
sources and mobile sources may pose greater risks. Further, EPA is 
currently developing a rule that would exempt MACT-regulated facilities 
from regulation under its residual risk program if, on the basis of 
risk assessments, the facilities demonstrate that the cumulative risks 
from all of their toxic emissions do not exceed certain thresholds. 
According to EPA, this strategy could achieve voluntary risk reductions 
from facilities that would not be required to reduce risks under the 
current residual risk program and will provide high-quality, site- 
specific emissions data for use in future assessments and emission 
reduction strategies. While this approach has the potential to ease the 
regulatory burden on low-risk facilities, EPA may have opportunities to 
apply its limited resources to approaches that have greater potential 
to reduce risks. 

Several of the Programs We Reviewed Conduct More Comprehensive 
Facilitywide Risk Assessments Than EPA: 

Several state and local programs we reviewed generally evaluate the 
emissions from all of the emissions points within a facility in a 
single risk assessment in order to assess the health risks associated 
with the entire facility. In contrast, EPA's residual risk assessments-
-aimed at identifying and mitigating any remaining health risk from 
emissions sources subject to MACT standards--have only evaluated risk 
from a portion of the facilities. Specifically, to date, EPA has 
limited the scope of its residual risk determinations to emissions 
points within facilities that must comply with the MACT standards at 
issue, although other emissions points may also emit air 
toxics.[Footnote 33] As a result, according to several state and local 
officials, some facilities with a high impact on public health may 
avoid additional control requirements because EPA's focus on limited 
portions of facilities may underestimate the risk posed by whole 
facilities. 

Figure 3 illustrates a facility emitting air toxics from four emission 
points. Of the four emission points within the facility, points 1 and 2 
are each covered by different MACT standards and, therefore, are 
subject to separate residual risk assessments. Emission points 3 and 4 
emit air toxics, but are not subject to MACT standards, because 
emissions from these two points do not exceed the MACT threshold. 

Figure 3: Emission Points at an Industrial Facility Emitting Air 
Toxics: 

[See PDF for image] 

Source: GAO. 

[End of figure] 

The programs we reviewed in California, Wisconsin, and Louisville would 
generally evaluate the emissions from all of the emissions points in 
this facility in a single risk assessment.[Footnote 34] In contrast, 
EPA's approach to date would be to conduct a residual risk assessment 
for emission point 1 that would consider the exposure and human health 
risk attributable to emissions from that emission point, and generally 
would not consider the emissions from point 2, which falls under a 
different MACT standard, or the emissions from points 3 and 4. 
According to EPA, it is not entirely precluded from considering 
emissions from additional emissions points not covered by the MACT 
standards at issue, but the agency, to date, has not exercised this 
discretion in a final rule. 

Several state and local stakeholders said that they were concerned that 
EPA's risk assessments may show a lower level of risk to the public 
than if the agency considered emissions from all of the emission points 
at the facility. They said that EPA's residual risk approach may 
exclude some facilities with a high impact on public health from more 
stringent control requirements. Several officials said it would make 
more sense, from a public health perspective, to consider the impact 
from all sources at the facility at once, as some states do, rather 
than review each emission point individually. Along these lines, 
several EPA officials said that evaluating all of the emissions from a 
facility simultaneously would enhance the efficiency of the program and 
better protect public health. 

Several Programs Have Systematic Approaches to Identify and Prioritize 
Air Toxics: 

Several of the state programs we reviewed use systematic approaches to 
identify and prioritize chemicals for addition to their air toxics 
lists. In contrast, EPA has not acted on the requirement to 
periodically review and revise the list of regulated federal air 
toxics.[Footnote 35] For example, California officials work with the 
state's public health agency to determine if a substance qualifies as a 
state air toxic. This process includes assessing (1) the potential for 
human exposure to a substance, (2) the chemical's cancer-causing 
potential, (3) any noncancer effects such as irritation of the lungs or 
nausea, and (4) the impact on children's health, among other factors. A 
panel of scientific experts reviews the work for accuracy, followed by 
the formal development of a regulation, including a public hearing. 
Similarly, Oregon works with a committee composed of toxicology, public 
health, and technical experts to periodically identify air toxics for 
review and to develop health-based emission benchmarks. The committee 
prioritizes air toxics for review based on Oregon's emission inventory, 
the pollutant's toxicity or potency, the number of people at risk, and 
the impact on sensitive populations such as children, among other 
factors spelled out in state regulations. The systematic approaches of 
these programs could inform EPA's efforts to meet the act's requirement 
to review and update the federal list of regulated air toxics. 

The Programs We Reviewed Stressed the Importance of Data on Emissions 
and Toxicology: 

Several of the state and local programs we reviewed require major and 
small stationary sources to submit standardized annual emissions 
reports and certify their accuracy. These programs, like EPA, rely on 
emissions inventory data to develop regulations and conduct risk 
assessments. For example, Wisconsin requires over 2,000 facilities to 
report emissions of 623 air toxics each year if the facility emits more 
than certain quantities of each pollutant. Facilities must certify the 
accuracy of their final submissions. The air toxics program in 
California similarly requires certain major and small stationary 
sources to report air toxics emissions of over 450 chemicals and to 
certify that the data are correct. New Jersey and Louisville have 
similar requirements for a smaller subset of air toxics and sources. 

In contrast to the programs that require sources to report and certify 
their emissions, EPA, to date, generally has not required emissions 
sources or state or local agencies to systematically report these 
data.[Footnote 36] Such data collection could enhance EPA's analysis 
and decision making in future air toxics rule makings. However, it is 
not clear how states without air toxics emissions inventories would 
comply with a federal requirement or the extent to which the data 
collected from the states would be comparable. For example, in 2002, 
EPA solicited comments on a rule to require state and local agencies to 
submit standardized air toxics emissions inventory data but the agency 
postponed consideration of the requirements partly due to concerns 
raised by state and local agencies about the lack of detail in EPA's 
proposal.[Footnote 37] EPA officials also told us that they had 
concerns over whether there is adequate statutory authority to collect 
these data. 

Officials representing the state and local programs we spoke with 
expressed mixed opinions about a potential EPA requirement to submit 
standardized air toxics emissions inventories. For example, officials 
in the states we reviewed except California supported a federal 
requirement to report air toxics emissions because it would improve the 
consistency of the federal inventory and its usefulness to states in 
activities such as risk assessment modeling. In addition, some state 
officials said that a federal requirement would enable states that are 
prohibited from having their own programs to collect information on 
emissions of air toxics. However, several officials cautioned that some 
programs would have difficulty meeting such a requirement without 
additional funding. California officials said that EPA should focus on 
states that do not currently have an inventory. 

In addition, state and local officials said that EPA does not regularly 
update chemical toxicity values that describe the potency of different 
air toxics--key information for conducting risk assessments. These 
officials told us that their agencies generally do not have the 
resources to develop quantitative risk estimates for air toxics and 
must rely on other sources of data, such as EPA's Integrated Risk 
Information System (IRIS). According to several officials, the basic 
science necessary to develop air toxics regulations is lacking in many 
cases. For example, Oregon officials cited limited and out-of-date 
toxicity values for a number of common chemicals in the IRIS database. 
Officials from other programs expressed similar concerns and said that 
EPA needed to enhance its efforts to provide quantitative toxicity 
information and conduct studies of sufficient quality to make 
determinations about chemical toxicity. A 2004 report by the National 
Academies also identified the need for more timely updates to EPA's 
IRIS database. In addition, California officials pointed out that EPA 
does not have a cancer toxicity value for diesel particulate matter, so 
some states have developed a patchwork of different toxicity values. 
Further, state and local officials questioned EPA's use of a 
formaldehyde risk factor developed by an industry group instead of its 
peer-reviewed IRIS value when developing a recent MACT standard for 
plywood and composite wood products.[Footnote 38] Several officials 
were concerned that the deviation from IRIS would cause confusion about 
what toxicology data were most accurate for state and local 
requirements. 

Conclusions: 

EPA has made some progress in controlling emissions of air toxics, but 
its overall implementation of the air toxics program falls short of the 
agency's statutory obligations because of the limited progress in (1) 
addressing requirements to limit emissions from small stationary 
sources and mobile sources, (2) evaluating the residual health risks 
associated with existing emissions standards and setting additional 
standards as appropriate, and (3) reviewing and updating the list of 
regulated pollutants, as appropriate. While EPA places a lower priority 
on air toxics than other programs that it believes have a greater 
potential to reduce adverse health effects from air pollution, more 
comprehensive information on the air toxics program's costs and 
benefits would help the agency compare the cost effectiveness of its 
investments in various clean air programs. Key data issues affecting 
the agency's ability to develop more comprehensive cost and benefit 
estimates include unreliable data on emissions and limited information 
on the extent to which changes in exposure to air toxics affect the 
incidence of adverse health effects. Until EPA supports efforts to 
address these data gaps that hinder its ability to evaluate the health 
risks of air toxics, the agency will not have assurance that its 
current priorities and programs necessarily target the areas of 
greatest opportunity for reducing health risks associated with air 
pollution. 

EPA still has a significant number of remaining requirements under the 
act, including (1) setting 54 emissions standards for small stationary 
sources; (2) conducting more than 90 reviews of the remaining health 
risks associated with emissions sources covered by its existing 
standards, and issuing additional standards as necessary; and (3) 
reviewing and updating, as appropriate, the list of regulated air 
toxics. Over the past 15 years, the air toxics program has not met its 
statutory deadlines, in part, because of its low priority relative to 
other programs and related funding constraints. Obtaining sufficient 
funding will continue to pose a challenge for EPA, especially in light 
of the nation's current fiscal situation. We believe that developing an 
implementation plan that identifies the remaining tasks, data needed to 
estimate the benefits of reductions in exposure to air toxics, 
timelines, and required funding would improve the management of the 
program as well as its transparency and accountability to Congress and 
the public. In addition, EPA could examine state and local approaches 
to air toxics that may have the potential to more effectively address 
risks by focusing resources on sources, communities, and geographic 
areas that face the greatest risks. This would require EPA to evaluate 
opportunities to enhance its efforts to focus on the greatest risks to 
human health within the current legislative framework. 

Recommendations for Executive Action: 

To improve the management of EPA's air toxics program and enhance its 
ability to reduce risks of cancer and other adverse health effects, we 
recommend that the EPA Administrator require the Assistant 
Administrator for Air and Radiation to develop an air toxics program 
improvement plan that incorporates the following five issues: 

* provides a detailed schedule for completing its mandated air toxics 
activities and identifies the staffing and funding resources needed to 
meet the schedule and address the health risk assessment needs; 

* prioritizes activities within the air toxics program, placing the 
highest priority on those actions that have the greatest potential to 
address health risks, to the extent permitted by the Clean Air Act; 

* establishes a process and timelines for meeting the act's 
requirements to periodically review and update the list of air toxics; 

* outlines an approach and timelines for improving the agency's ability 
to measure the program's costs and benefits; and: 

* describes how the agency plans to improve its air toxics emissions 
inventory, including a discussion of the statutory authority for, and 
the merits of, requiring states and emissions sources to submit 
standardized emissions data. 

Agency Comments: 

We provided EPA's Office of Air and Radiation with a copy of this 
report for review and comment. In commenting on the report, the Acting 
Assistant Administrator for Air and Radiation said that EPA agrees in 
part with the conclusions and recommendations in the report. The agency 
did not identify specific aspects of our conclusions or recommendations 
with which it disagreed, but rather provided only clarifications to 
statements in the report regarding the availability of information on 
the costs and benefits of the agency's efforts to control air toxics, 
the agency's progress in completing certain air toxics requirements of 
the Clean Air Act, and on EPA's management of the remaining 
requirements. EPA's letter and our response to their clarifications are 
included as appendix IV. EPA also provided technical comments, which we 
have incorporated, as appropriate. 

As agreed with your offices, unless you publicly announce the contents 
of this report earlier, we plan no further distribution until 30 days 
from the report date. At that time, we will send copies to the EPA 
Administrator and other interested parties. We will also make copies 
available to others upon request. In addition, the report will be 
available at no charge on the GAO Web site at [Hyperlink, 
http://www.gao.gov]. 

If you or your staff have any questions about this report, please 
contact me at (202) 512-3841 or stephensonj@gao.gov. Contact points for 
our Offices of Congressional Relations and Public Affairs may be found 
on the last page of this report. Key contributors to this report are 
listed in appendix V. 

Signed by: 

John B. Stephenson: 
Director, Natural Resources and Environment: 

List of Congressional Requesters: 

The Honorable James M. Jeffords: 
Ranking Minority Member: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Lincoln Chafee: 
Chairman: 
Subcommittee on Fisheries, Wildlife and Water: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Barbara Boxer: 
Ranking Minority Member: 
Subcommittee on Superfund and Waste Management: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Thomas R. Carper: 
Ranking Minority Member: 
Subcommittee on Clean Air, Climate Change, and Nuclear Safety: 
Committee on Environment and Public Works: 
United States Senate: 

The Honorable Hillary Rodham Clinton: 
United States Senate: 

The Honorable Patrick J. Leahy: 
United States Senate: 

The Honorable Joseph I. Lieberman: 
United States Senate: 

The Honorably Paul Sarbanes: 
United States Senate: 

The Honorable Olympia J. Snowe: 
United States Senate: 

The Honorable John D. Dingell: 
Ranking Minority Member: 
Committee on Energy and Commerce: 
House of Representatives: 

The Honorable Tom Allen: 
House of Representatives: 

The Honorable Lois Capps: 
House of Representatives: 

The Honorable Edward J. Markey: 
House of Representatives: 

The Honorable Hilda L. Solis: 
House of Representatives: 

The Honorable Henry A. Waxman: 
House of Representatives: 

[End of section] 

Appendix I: Status of EPA's Efforts to Respond to Recommendations in 
the National Academies' Report on Air Quality: 

This appendix discusses the Environmental Protection Agency's (EPA) 
response to the findings and recommendations of the National Academies' 
(Academies) report on air quality management. The Academies prepared 
this report in response to a congressional request for an independent 
evaluation of the effectiveness and implementation of the Clean Air 
Act. The report examined the roles of science and technology in the 
implementation of the act and recommended ways to improve air quality 
management. One of the report's key recommendations was for EPA to form 
a work group to evaluate the report and provide a detailed list of 
actions EPA could take to improve its implementation of clean air 
programs. The work group completed this review in December 2004 and 
provided the agency's Clean Air Act Advisory Committee with a list of 
38 recommendations. 

EPA's Office of Policy Analysis and Review has taken the lead in 
responding to the recommendations and provided an initial response in 
April 2005, which was updated in November 2005.[Footnote 39] The 
response included information about ongoing and proposed activities to 
address the recommendations and estimated time frames for responding to 
each recommendation. The agency has prioritized the recommendations and 
developed a proposed schedule for completing its activities, with some 
actions already under way or completed and others not scheduled for 
completion until fiscal year 2008. Based on our review of available 
documents and discussions with EPA program managers, the agency has 
taken affirmative steps to respond to a number of the recommendations, 
and its proposed actions generally appear responsive to the Academies' 
findings. A comprehensive evaluation of EPA's response to the 
Academies' recommendations will not be possible until the agency has 
made further progress in implementing its proposed response actions. 

[End of section] 

Appendix II: Objectives, Scope, and Methodology: 

We were asked to assess (1) EPA's progress toward implementing the air 
toxics program and any implementation challenges the agency faces, (2) 
what available information indicates about the costs and benefits of 
EPA's efforts to control air toxics, and (3) the program design and 
management practices of state and local air toxics programs that could 
potentially help EPA enhance the effectiveness of the federal program. 
In addition, we were asked to assess EPA's progress in responding to 
recommendations pertaining to the air toxics program made by the 
National Academies in 2004. 

To respond to the first objective, we updated our previous analysis of 
the agency's progress in implementing program requirements. We reviewed 
the requirements of the Clean Air Act Amendments of 1990 and EPA's 
actions to respond to these requirements, including the number of 
regulations the agency promulgated and other requirements to issue 
reports and guidance. Specifically, we considered EPA's Maximum 
Achievable Control Technology (MACT), small stationary source, mobile 
source, residual risk, and technology review activities, and other 
activities in the act that were specifically related to air toxics. 

We also evaluated the timeliness of EPA's actions versus the schedule 
mandated by the act by comparing the dates specified in the act with 
the dates on which EPA published the rules in the Federal Register. We 
independently developed a list of actions required by EPA and worked 
with agency officials to refine and confirm the list we used. We made 
minor modifications to the list approved by EPA to account for the 
promulgation of residual risk and area source standards, to separately 
count area source standards issued in conjunction with MACT standards, 
and to delete source categories that were delisted. 

To determine the priority of the air toxics program relative to other 
air programs, and the priorities within the air toxics program, we met 
with senior air program officials and analyzed budget data submitted by 
EPA. Specifically, we compared the funding for EPA's air program as a 
whole with the funding for the air toxics program. 

To identify the implementation challenges EPA faces, we reviewed 
available studies by the National Academies, the Office of Management 
and Budget (OMB), and the EPA Inspector General. We identified nine 
implementation challenges, such as the adequacy of program funding and 
the priority of the program relative to other air programs, and 
developed a structured interview in order to evaluate the magnitude of 
the challenges identified by these studies in the opinions of various 
stakeholders. We pretested the interview questions and made relevant 
changes to the questions based on the pretest. 

We designed the structured interview so that respondents could rate 
each implementation challenge on a scale from 0 (not a challenge at 
all) to 4 (a challenge to a very great extent). When conducting the 
interviews, we asked followup questions if the respondents rated the 
challenge as a 3 (a challenge to a large extent) or 4, such as what 
they thought could be done to address the challenge. We also provided a 
list of key definitions, an explanation of the rating system, and a 
description of each challenge to respondents prior to conducting each 
interview. 

We conducted structured interviews with a nonprobability 
sample[Footnote 40] of 22 officials, including 8 EPA, 5 industry, 4 
environmental, and 5 state and local officials. Specifically, for EPA, 
we interviewed senior officials within the Office of Air Quality 
Planning and Standards and the Office of Transportation and Air 
Quality. We identified national-level environmental and industry 
stakeholders through consultation with EPA (and referrals from contacts 
identified through this consultation) and membership on the Clean Air 
Act Advisory Committee. The five industry groups we interviewed were 
the American Forest & Paper Association, the American Petroleum 
Institute, the Council of Industrial Boiler Owners, the American 
Chemistry Council, and the Alliance of Automobile Manufacturers. The 
four environmental groups we interviewed were the Natural Resources 
Defense Council, Environmental Defense, Earth Justice, and an air 
toxics consultant recommended by environmental stakeholders and EPA. We 
interviewed officials from state and local programs in California, New 
Jersey, Oregon, Wisconsin, and Louisville, Kentucky. 

Following the structured interviews, we determined the most significant 
challenges for all of the stakeholders by averaging the ratings from 
all 22 respondents for each challenge. However, because ratings of the 
most significant challenges differed for each stakeholder group, we 
also averaged the scores for each challenge for each stakeholder group. 
We identified the greatest challenges identified by each stakeholder 
group (an average rating of 3 or higher, or those rated as challenges 
to a large or very great extent) to assess how perceptions of the 
challenges differed among the stakeholder groups. 

To respond to the second objective, we analyzed available information 
on the economic impacts of the program, as well as data on trends in 
emissions, health risks, and compliance. Regarding data on economic 
impacts, we reviewed EPA's 1997 and 1999 reports to Congress on the 
economic impacts of the Clean Air Act as well as the agency's guidance 
for analyzing the effects of air pollution regulations. We also met 
with EPA staff in the Office of Air Quality Planning and Standards and 
Office of Policy Analysis and Review responsible for analyzing the 
economic effects of clean air regulations. Regarding emissions and 
monitoring data, we met with EPA staff responsible for maintaining the 
National Emissions Inventory, reviewed the agency's documentation and 
plans for improving the inventory, and reviewed relevant reports by 
EPA's Inspector General. Regarding data on health and risks, we met 
with EPA staff responsible for risk assessment and the development of 
the National-Scale Air Toxics Assessment. We also reviewed EPA's 
methodology for developing the assessment and available information on 
the risk assessment process. We obtained compliance data from the 
Office of Enforcement and Compliance Assurance's Air Facility 
Subsystem. We reviewed these data for obvious completeness and 
consistency problems, reviewed available documentation, and interviewed 
the system administrator. Unless otherwise noted, we determined the 
data were sufficiently reliable for the purposes of this report. 

To respond to the third objective, we reviewed a nonprobability sample 
of air toxics programs from California, New Jersey, Oregon, and 
Wisconsin and from Louisville, Kentucky to identify innovative program 
designs or management practices. We focused on programs that (1) went 
beyond federal standards, (2) were identified by EPA and other 
stakeholders as innovative programs, (3) used strategies to address air 
toxics that differed from those used by EPA, and (4) represented a 
range of geographic locations and experience addressing air toxics. 
Specifically, we asked EPA and the State and Territorial Air Pollution 
Program Administrators and the Association of Local Air Pollution 
Control Officials (STAPPA/ALAPCO), the stakeholders most knowledgeable 
about state and local air toxics programs, whether there were specific 
programs we should review, and used their recommendations as selection 
criteria. GAO conducted independent research to confirm that the 
selections cited by these stakeholders were reasonable, including 
analyses of the stringency of state and local air toxics programs based 
on current law, policy, and guidance documents and summary documents 
developed by EPA and state and local agencies. 

We visited each program selected for review and conducted 
semistructured interviews with state and local officials. We developed 
an interview protocol and revised it after limited testing with 
respondents. The semistructured interview included questions about how 
the programs interact with EPA, how the program views EPA's current and 
future requirements, regulate different chemicals and sources, account 
for risk, collect emissions inventory data, and measure progress, among 
other factors. We focused primarily on practices that EPA might find 
useful in addressing its program implementation challenges and did not 
evaluate the effectiveness of the state and local programs we reviewed. 
Our discussion of the practices employed by these programs should not 
be construed as an endorsement of any particular approach but rather as 
an acknowledgement that alternative strategies exist. 

In addition, we obtained information about EPA's response to the 
recommendations of the National Academies' 2004 report entitled Air 
Quality Management in the United States. We reviewed the 
recommendations in the report, the associated recommendations of the 
Clean Air Act Advisory Committee, and EPA's actions to respond to these 
recommendations. We worked with EPA officials to determine whether 
EPA's actions addressed the recommendations. Our work included an 
assessment of data reliability and internal controls. We conducted our 
work from June 2005 to June 2006 in accordance with generally accepted 
government auditing standards. 

[End of section] 

Appendix III: Profiles of State and Local Air Toxics Programs: 

This appendix provides general information on the nonprobability sample 
of four state and one local air toxics programs we reviewed to identify 
innovative program designs or management practices. We focused on 
programs that (1) went beyond federal standards, (2) were identified as 
innovative by EPA and other stakeholders, (3) used strategies to 
address air toxics that differ from EPA's, and (4) represented a range 
of geographic locations and experience addressing air toxics. Table 12 
presents basic information about the programs we reviewed, followed by 
profiles of each program. 

Table 12: Selected State and Local Air Toxics Programs: 

Program: State: California; 
Date created: 1983; 
Number of chemicals: 245; 
Strategy: Control technology; 
Description: Requires certain large and small stationary sources to 
apply control technologies to reduce emissions. 

Program: State: California: 
Date created: 1987; 
Number of chemicals: 451; 
Strategy: Risk assessment; 
Description: Requires certain large and small stationary sources to 
report emissions of air toxics, estimate the public health impact of 
their emissions, and reduce emissions as necessary to meet health-based 
standards. 

Program: State: New Jersey; 
Date created: 1979; 
Number of chemicals: 237; 
Strategy: Control technology and risk assessment; 
Description: Requires certain facilities seeking permits to apply air 
toxics emission control technology, estimate the risk posed by the 
remaining emissions, and take additional measures as necessary to meet 
health-based targets. 

Program: State: Oregon[A]; 
Date created: 2003; 
Number of chemicals: 49[B]; 
Strategy: Geographic, control technology, and risk assessment; 
Description: Requires facilities in specific geographic areas of high 
risk to develop, with other stakeholders, a risk reduction plan to meet 
health-based benchmarks. In addition, some stationary sources may be 
required to apply control technologies and estimate and mitigate the 
risk they pose to the public. 

Program: State: Wisconsin; 
Date created: 1988; 
Number of chemicals: 535; 
Strategy: Control technology and risk assessment; 
Description: Requires certain facilities that emit specific amounts of 
cancer-causing air toxics to apply control technology to reduce 
emissions. Certain facilities that emit specific amounts of other air 
toxics must estimate the risks posed by these chemicals and meet health 
based standards. 

 

Program: Local: Louisville, Kentucky; 
Date created: 2005; 
Number of chemicals: 191; 
Strategy: Risk assessment; 
Description: Requires certain facilities seeking permits to construct 
or modify processes or equipment to estimate the risk posed by their 
air toxics emissions and to reduce the risk, potentially through the 
application of control technologies, to meet certain health-based 
goals. Certain existing facilities must meet similar requirements for 
37 chemicals. 

Source: GAO analysis of state and local agency data. 

[A] Oregon's program is still being developed and has not been fully 
implemented. This description presents the requirements as spelled out 
in the 2003 state rule that created the program. 

[B] The Oregon Department of Environmental Quality proposed to adopt 
benchmarks for 49 air toxics in February 2006. The benchmarks were not 
final as of the date of this report. 

[End of table] 

California: 

California's air toxics program regulates certain new and existing 
major stationary sources, small stationary sources, and mobile sources 
more stringently than EPA. In 1983, the state legislature adopted 
Assembly Bill 1807, the Toxic Air Contaminant Identification and 
Control Act, which defined a process for identifying chemicals that 
qualify as state air toxics and developing control standards to reduce 
emissions from certain sources based on the application of pollution 
control technology. California has listed 245 toxic air contaminants as 
of May 2006. The state regulates diesel particulate matter emissions 
from motor vehicles, such as school buses, under its program. 

In 1987, the state legislature passed an additional law, Assembly Bill 
2588, the Air Toxics "Hot Spots" Information and Assessment Act, which 
required the submission of air toxics emissions inventory data from 
certain facilities and notification of local residents of significant 
risk from nearby sources of air toxics. Under this act, certain sources 
of air toxics must conduct risk assessments to determine their health 
impact on the community. In conducting these risk assessments, 
regulated facilities must consider the risks posed by their emissions 
of 451 different chemicals.[Footnote 41] In 1992, the legislature 
passed an amendment to the "hot spots" law that required facilities 
that pose a significant health risk to the community to develop risk 
management plans. Policy documents and other information are available 
at the program's Web site [Hyperlink, 
http://www.arb.ca.gov/toxics/toxics.htm].  

New Jersey: 

New Jersey's air toxics program regulates certain large and small 
stationary sources more stringently than EPA through the state's 
permitting program. The New Jersey Air Pollution Control Act of 1954 
requires new or modified sources that emit air pollutants, including 
air toxics, to incorporate state-of-the-art air pollution controls to 
reduce their emissions. In 1979, the New Jersey Department of 
Environmental Protection (DEP) adopted a regulation that specifically 
addressed air toxics emissions. This rule listed 11 air toxics and 
required sources emitting these chemicals to register with DEP and 
demonstrate that they utilize state-of-the-art controls to limit their 
emissions. The department incorporates control requirements for other 
air toxics on a case-by-case basis as part of the permitting process. 
In the early 1980s, the DEP instituted a risk assessment policy to 
better ensure that sources with state-of-the-art controls protect 
public health. The risk assessment policy requires certain facilities 
seeking permits to estimate the risk to the community that remains 
after the application of technology standards and to take additional 
measures as necessary to meet health-based targets established for 237 
air toxics. General information about New Jersey's air toxics program 
is available at [Hyperlink, 
http://www.state.nj.us/dep/airmon/airtoxics/], and policy documents, 
such as risk assessment policies are available at [Hyperlink, 
http://www.state.nj.us/dep/aqpp/risk.html]. 

Oregon: 

Oregon's air toxics program is authorized to go beyond federal 
requirements for some large and small stationary sources. In November 
1998, the Oregon Department of Environmental Quality (DEQ) convened a 
broad-based stakeholder group to outline a program to complement the 
existing federal program and reduce the impact of air toxics in Oregon. 
DEQ worked with stakeholders until the adoption of Oregon's air toxics 
rule on October 9, 2003. The rule requires sources in specific 
geographic areas of high risk to develop, with other stakeholders, a 
risk reduction plan to meet certain health based goals.[Footnote 42] In 
addition, some stationary sources may be required to estimate and 
mitigate the risk they pose to the public and apply control 
technologies. The program is still being developed and has not been 
fully implemented. Policy and guidance documents and other information 
are available at the program's Web site [Hyperlink, 
http://www.deq.state.or.us/aq/hap/index.htm]. 

Wisconsin: 

Wisconsin's air toxics program regulates certain new and existing 
stationary sources more stringently than EPA. In 1983, the Wisconsin 
Department of Natural Resources (DNR) formed a group of scientists, 
industry, environmental, and government stakeholders in response to 
public concern about the health effects of air toxics and the lack of 
policy and regulations at the federal level. The group recommended an 
approach for a state air toxics rule in 1985, and DNR developed a rule 
that became effective in 1988. This original rule was rewritten and 
redeveloped from 2000 through 2004 using an advisory committee process 
that included government, industry, and environmental stakeholders. The 
final rule became effective in July 2004. The rule lists 535 air toxics 
and requires certain facilities that emit specific amounts of cancer- 
causing air toxics to apply control technology to reduce emissions. In 
addition, certain facilities that emit other air toxics beyond specific 
thresholds must estimate the risks posed by these chemicals and meet 
health-based standards.[Footnote 43] Guidance documents and other 
information are available on the program's Web site, [Hyperlink, 
http://www.dnr.state.wi.us/org/aw/air/health/airtoxics/]. 

Louisville, Kentucky: 

In September 2004, the Louisville Metro Air Pollution Control District 
prepared a draft Strategic Toxic Air Reduction (STAR) program in 
response to air monitoring that documented and modeled data that 
suggested that air toxics posed significant risks to the community. 
Adopted by the Louisville Metro Air Pollution Control Board in June 
2005, the STAR program requires certain facilities to estimate the risk 
posed by their air toxics emissions and to reduce the risk, potentially 
through the application of control technologies, to meet certain health-
based goals. Louisville's program first focuses on emissions of 18 air 
toxics that posed unacceptable risk to the public based on monitoring 
studies. In total, the STAR program applies to new or modified 
processes and process equipment that will emit any of 191 air toxics, 
and existing sources that emitted any of 37 air toxics in quantities 
that exceed certain thresholds. Policy documents and other information 
are available on the program's Web site, [Hyperlink, 
http://www.apcd.org/star/]. 

[End of section] 

Appendix IV: Comments from the Environmental Protection Agency: 

Note: GAO comments supplementing those in the report text appear at the 
end of this appendix. 

United States Environmental Protection Agency: 
Washington, D.C. 20460: 

Office Of Air And Radiation: 

Jun 8 2006: 

Mr. John B. Stephenson: 
Director, Natural Resources and Environment: 
U. S. Government Accountability Office: 
Washington, DC 20548: 

Dear Mr. Stephenson: 

The U. S. Environmental Protection Agency (EPA) appreciates the 
opportunity to review and comment on the Government Accountability 
Office (GAO) report, "Clean Air Act: EPA Should Improve the Management 
of Its Air Toxics Program" (GAO-06-669). EPA agrees in part with the 
conclusions and recommendations in the report and would like to provide 
clarification on several statements in the report. 

"Available information on the costs and benefits of EPA's efforts to 
control air toxics is not sufficiently comprehensive to measure the 
total economic impacts resulting from the air toxics program." 

Realizing the limitations of a chemical-by-chemical decision framework 
based solely on risk, the 1990 Clean Air Act Amendments mandated a 
different, two-phased approach. In the first phase, EPA develops 
technology-based standards, requiring sources to meet specific 
emissions limits that are based on emissions levels already being 
achieved by many similar sources in the country. In the second phase, 
EPA applies a risk-based approach to assess how these technology-based 
emissions limits are reducing health and environmental risks, and EPA 
may implement additional standards to address any significant remaining 
risk (or "residual risk"). 

In February 2004, EPA completed the issuance of the technology-based 
standards for categories of industries that emit toxic emissions at 
major-source levels. In total, EPA issued 96 standards (known as 
Maximum Achievable Control Technology or MALT) standards covering 174 
industrial operations. When all of these industry categories come into 
full compliance in 2007, these MACT standards will cut annual air 
toxics emissions by an estimated 1.7 million tons. Implementation of 
these standards results in significant reductions of volatile organic 
compounds (VOCs) and particulate matter (PM) which carry benefits with 
well-established means of quantification; quantification of the health 
benefits of reducing air toxics (e.g., reduced cancer risks and 
incidence, reduced risks of acute and chronic noncancer health effects) 
is more problematic.  

Since completing the MACT standards, EPA has assessed the health risks 
associated with 8 of those standards and concluded that 4 of the 
standards present no significant known health risks that would warrant 
making them more stringent. For the other 4 standards, we have proposed 
or will propose more stringent standards to reduce health risks in 
order to provide public health protection with an ample margin of 
safety. Each of these proposed actions will reduce air toxics exposures 
and levels of individual cancer or other health risks for people living 
near the affected facilities. We are still developing ways of 
specifically quantifying these benefits. However, the two-step approach 
embodied in the 1990 Clean Air Act Amendments allows EPA to focus risk 
assessment and benefits analysis efforts on the smaller number of key 
HAPs posing potentially significant residual risks. EPA believes this 
more focused approach will provide better support to future air toxics 
rulemaking decisions than would the comprehensive assessment of the 
total benefits and costs of all air toxics controls referenced in GAO's 
comment. 

"EPA has made little progress and is behind schedule in completing 
residual risk and technology reviews and in issuing emissions standards 
for small stationary and mobile sources." 

In several places, the GAO report refers to this "limited progress" in 
implementing mobile source requirements and in reducing mobile source 
emissions and risks. In fact, we estimate a 57% reduction in emissions 
of mobile source air toxics between 1990 and 2007. Since actions that 
address mobile source air toxics resulted in additional reductions 
prior to 1990, this is actually an underestimate of the overall 
reduction from EPA programs. These dramatic reductions will continue in 
the future, with a 60% reduction between 1999 and 2020. (See Attachment 
1 for the contribution of source categories to air toxics emissions, 
1990-2020, not including diesel particulate matter.) For diesel 
particulate matter emissions specifically, we expect a 70% reduction 
between 1999 and 2020[Footnote 44]. These emission reductions, and the 
large number of standards EPA has promulgated since 1990 for many 
different mobile sources of toxics emissions, illustrate that EPA has 
in fact made significant progress in reducing mobile source air toxics. 

The limited progress cited in the GAO report appears to use a measure 
of progress based on the number of actions taken under Clean Air Act 
section 202(1), which is the provision that specifically applies to 
motor vehicle air toxics. We believe that this is an inappropriately 
narrow measure of progress. EPA controls mobile source air toxics in 
the broader context of motor vehicle, nonroad engine and fuel 
standards, regardless of whether they are issued under 202(1) 
specifically. This is often done through standards which reduce 
hydrocarbons and particulate matter, because such standards also reduce 
air toxics. 

The Clean Air Act itself recognizes that mobile source toxics control 
is achieved in the broader context of motor vehicle and fuel standards, 
regardless of whether they are issued under 202(1) specifically. For 
example, Clean Air Act section 202(1) recognizes that mobile source air 
toxics are controlled under the broader authority of 202(a) and 211(c), 
which refer to standards for vehicles and fuels. It requires EPA to use 
these authorities for the purpose of controlling air toxics, and it 
also requires EPA, when setting such toxics standards, to consider the 
standards already established under section 202(a). In addition, the 
specific wording of section 202(1) applies only to "motor vehicles," a 
term which excludes nonroad equipment. However, EPA has clearly 
recognized that nonroad mobile sources are an important source of 
mobile source air toxics and has controlled them accordingly, through 
authorities other than 202(1). When EPA's actions under all these 
authorities are considered-along with the toxics emissions reductions 
they produce-it is clear that EPA has made significant progress in 
controlling mobile source air toxics. (See attachments 2 and 3 for more 
details.) 

"The agency lacks a comprehensive strategy for managing its 
implementation of the remaining air toxics requirements." 

The Clean Air Act itself presents a road map for air toxics with 
distinct phases and specific timeframes. EPA has supplemented the 
statutory roadmap with more specific strategies. First, in 1999 EPA 
finalized the Integrated Air Toxics Strategy. This strategy fulfilled 
the mandate from Congress to develop a strategy for air toxics in urban 
areas. The strategy includes specific actions to address the large 
number of smaller, area sources, and contains broader risk reduction 
goals encompassing all stationary sources. The Integrated Air Toxics 
Strategy is EPA's framework for addressing air toxics in urban areas by 
looking at stationary, mobile, and indoor source emissions. Air toxics 
can pose special threats in urban areas because of the large number of 
people and the variety of sources of toxic air pollutants, such as 
cars, trucks, large factories, gasoline stations, and dry cleaners. EPA 
is also concerned about the impact of toxic emissions on minority and 
low-income communities, which are often located close to industrial and 
commercial urbanized areas. 

Second, EPA is developing a strategy to meet the aggressive schedule 
established by the U.S. Court of Appeals for the D.C. Circuit. The 
schedule requires completion of the remaining 50 standards governing 
emissions from area sources by mid-2009. The Agency is evaluating 
available information about the source categories and exploring 
different ways of writing standards that could address multiple source 
categories in one or a relatively smaller number of rules. We are also 
considering alternative standards that could support a more flexible 
and adaptive approach to controlling emissions from certain source 
categories in recognition of ongoing efforts by State and local 
agencies to comply with their own air toxics control programs and 
federally-mandated programs to reduce ozone and particulate matter. 
Under the court-imposed deadlines, the earliest set of standards may 
involve control requirements for source categories about which we have 
the most reliable information. Categories for which we have relatively 
less information or where more significant control efforts may be 
warranted will likely be addressed in the later deadlines contained in 
the court schedule. 

Third, EPA is developing a strategy for completing the residual risk 
and technology review program. EPA recognizes that there have been 
problems with completing these reviews within the statutorily-required 
8-year period following promulgation of the major source standards. 
However, we are learning important lessons from the experiences gained 
in our first eight reviews. The cost of these efforts in time, staff, 
and contract resources, relative to results achieved, lead us to seek 
different ways to meet our statutory obligations and ensure the 
public's health is adequately protected. For this reason, we are 
examining a variety of options that go beyond the conventional source 
category, standard- specific approach to consider such things as the 
risk posed comprehensively by all of the emitting activities at an 
affected facility, and evaluating screening options to determine which 
industries and/or standards merit more rigorous examination. We believe 
this approach will allow us to more efficiently identify and address 
significant remaining risks posed by air toxics from stationary 
sources, while reducing the expenditure of resources on standards 
likely to pose little or no residual risk. 

Once again, thank you for the opportunity to respond. 

Sincerely, 

Signed by:  

William L Wehrum: 
Acting Assistant Administrator: 

Enclosures: 

Attachment 1: 

Contribution of Source Categories to Air Toxic Emissions, 1990 to 2020 
(not including diesel particulate matter).

[See PDF for Image] 

Note: Dashed line represents projected emissions without Clean Air Act 
controls. 

[End of Figure] 

Attachment 2: 

Current On-Highway Engine and Vehicle Programs Providing Significant 
Additional MSAT Reductions. 

Category: Light-duty cars and trucks; 
Rule and FRM date: Tier 2 (including low sulfur fuel and enhanced 
evaporative emissions), February 10, 2000; 
Implementation Schedule: 2004-2009; 
VOC Standards*: check; 
PM standards: check. 

Category: Light-duty cars and trucks; 
Rule and FRM date: NLEV (National Low-Emitting Vehicle); 
Implementation Schedule: 1999-2003; 
VOC Standards*: check; 
PM standards: check. 

Category: Light-duty cars and trucks; 
Rule and FRM date: SFTP (Supplemental FTP) Procedures; 
Implementation Schedule: 2001 (start); 
VOC Standards*: check; 
PM standards: [Empty]. 

Category: Heavy-duty trucks; 
Rule and FRM date: 2004 Heavy-duty Rule October 6, 2000; 
Implementation Schedule: 2004-2007; 
VOC Standards*: check; 
PM standards: check. 

Category: Heavy-duty trucks; 
Rule and FRM date: 2007 Heavy-duty Rule (including low sulfur fuel), 
January 18, 2001; 
Implementation Schedule: 2007-2010; 
VOC Standards*: check; 
PM standards: check. 

Category: Urban Buses; 
Rule and FRM date: HD Diesel Retrofit; 
Implementation Schedule: 1994-1998; 
VOC Standards*: [Empty]; 
PM standards: check. 

Category: Highway Motorcycles; 
Rule and FRM date: December 2003; 
Implementation Schedule: 2006-2010; 
VOC Standards*: check; 
PM standards: [Empty]. 

* Standards in various forms including HC, NMHC, NMOG, and NOx+NMHC. 

[End of Table] 

Attachment 3: Current Nonroad Engine/Vehicle Programs. 

Category: Land-based diesel; 
Rule and FRM date: Tier 2, October 23, 1998; 
Implementation Schedule: 2001-2006; 
VOC standards*: check; 
PM Standards: check. 

Category: Land-based diesel; 
Rule and FRM date: Tier 3, October 23, 1998; 
Implementation Schedule: 2006-2008; 
VOC standards*: check; 
PM Standards: check. 

Category: Land-based diesel; 
Rule and FRM date: Tier 4 (with low sulfur fuel), June 29, 2004; 
Implementation Schedule: 2008-2014; 
VOC standards*: check; 
PM Standards: check. 

Category: Locomotives; 
Rule and FRM date: Tier 0, Tier 1, Tier 2, April 16, 1998; 
Implementation Schedule: 2002-2005; 
VOC standards*: check; 
PM Standards: check. 

Category: Marine; 
Rule and FRM date: Spark-ignition Gasoline Engine standards, October 4, 
1996; 
Implementation Schedule: 1998-2006; 
VOC standards*: check; 
PM Standards: [Empty]. 

Category: Marine; 
Rule and FRM date: Diesel engines, less than 50hp; 
Implementation Schedule: 1999-2005; 
VOC standards*: [Empty]; 
PM Standards: check. 

Category: Marine; 
Rule and FRM date: Recreational diesel, November 8, 2002; 
Implementation Schedule: Starting 2006/2009; 
VOC standards*: check; 
PM Standards: check. 

Category: Marine; 
Rule and FRM date: Commercial diesel, February 28, 2003; 
Implementation Schedule: Starting 2004/2007; 
VOC standards*: check; 
PM Standards: check. 

Category: Large spark-ignition engines; 
Rule and FRM date: Tier 1 standards, Tier 2 standards, November 8, 
2002; 
Implementation Schedule: 2004-2007, Starting 2007; 
VOC standards*: check; 
PM Standards: [Empty]. 

Category: Small spark-ignition engines; 
Rule and FRM date: Phase 1 standards; 
Implementation Schedule: 1997-2007; 
VOC standards*: check; 
PM Standards: [Empty]. 

Category: Small spark-ignition engines; 
Rule and FRM date: Handheld Phase 2 standards, April 25, 2000; 
Implementation Schedule: 2002-2007; 
VOC standards*: check; 
PM Standards: [Empty]. 

Category: Small spark-ignition engines; 
Rule and FRM date: Non-handheld Phase 2 Standards, March 30, 1999; 
Implementation Schedule: 2001-2007; 
VOC standards*: [Empty]; 
PM Standards: [Empty]. 

Category: Aircraft (NOx Std in 2005; Smoke Std in 1982); 
Rule and FRM date: [Empty]; 
Implementation Schedule: No current/recent standards for VOC or PM; 
VOC standards*: [Empty]; 
PM Standards: [Empty]. 

Category: Recreational vehicles; 
Rule and FRM date: November 8, 2002; 
Implementation Schedule: 2006-2012; 
VOC standards*: check; 
PM Standards: [Empty]. 

* Standards in various forms including HC, NMHC, NMOG, and NOx+NMHC. 

[End of Table] 

GAO comments: 

1. Regarding our discussion of the economic effects of air toxics 
regulations, EPA stated that the agency finds it appropriate to focus 
risk assessments and benefits analysis on the air toxics that pose the 
most significant risks within the context of the residual risk program. 
EPA's letter also stated that such an approach would assist the 
rulemaking process to a greater extent than comprehensive assessments 
of the total benefits and costs of all air toxics controls. While EPA 
may hold this view, the Clean Air Act requires the agency not only to 
assess residual risks after completing the MACT standards, but also to 
periodically assess the costs and benefits of clean air programs. 
Regarding the first set of requirements, EPA was late in issuing almost 
all of the MACT standards and is already well behind schedule in 
completing the residual risk assessments. With respect to the second 
set of requirements, EPA's economic assessments of clean air programs 
have included limited information on the costs of regulating air toxics 
and have not included monetized estimates of the human health or other 
benefits--either for individual pollutants or for all of the pollutants 
in total. More complete information on costs and benefits would help 
the agency, Congress, and the public understand the effects of the air 
toxics program and enable the agency to compare the net benefits of the 
air toxics program with those achieved under other clean air programs 
on which the agency has placed a higher priority. 

2. In its letter, EPA stated that GAO uses an inappropriately narrow 
measure of progress in regulating air toxics and that the agency has 
issued a number of regulations that control air toxics as a side 
benefit. However, as we discuss in the report, data limitations 
compromise the usefulness of other performance measures. EPA has indeed 
taken regulatory actions outside of the air toxics program that control 
toxic emissions as a side benefit. However, the progress--in terms of 
emissions reductions--that EPA cites should be considered in the 
context of the limitations of the emissions data discussed in this 
report. For example, the EPA Inspector General has reported that EPA 
cannot tell whether apparent reductions or increases in emissions have 
resulted from changes in the way the agency estimates emissions or from 
actual reductions. It is also important to note that EPA does not 
expect some of the emissions reductions cited in its letter to occur 
until 2020. Furthermore, EPA's most recent data on risks from air 
toxics identifies benzene--a known carcinogen emitted primarily by 
mobile sources--as a national risk driver that accounts for 25 percent 
of the cancer risks posed by air toxics across the nation. This 
suggests that EPA has substantial opportunities to further address air 
toxics risks from mobile sources. Finally, the Clean Air Act mandated 
specific actions and timelines for evaluating and regulating toxic 
emissions from mobile sources. As discussed in this report, the agency 
has missed its deadlines for completing these actions but has proposed 
a mobile source air toxics rule that it intends to finalize in 2007. 

3. In response to our finding that EPA lacks a strategy for managing 
its implementation of the remaining air toxics requirements, the 
agency's letter stated that the Clean Air Act provides a road map for 
air toxics and that EPA developed an integrated air toxics strategy in 
1999. EPA also stated that the agency is developing a strategy to 
respond to its court-ordered deadlines for completing certain air 
toxics requirements. As discussed in the report, EPA has missed most of 
the act's deadlines related to air toxics and has not fully implemented 
the actions outlined in its integrated strategy. Additionally, EPA's 
discussion of its efforts to meet court-ordered deadlines underscores 
the need for more proactive management. 

[End of section] 

Appendix V: GAO Contact and Staff Acknowledgments: 

GAO Contact: 

John B. Stephenson, (202) 512-3841 or stephensonj@gao.gov: 

Staff Acknowledgments: 

In addition to the contact named above, Christine Fishkin (Assistant 
Director), Jennifer Dougherty, Cindy Gilbert, Tim Guinane, Michael Hix, 
Andrew Huddleston, Karen Keegan, Alison O'Neill, Judy Pagano, Melissa 
Saddler, and Joseph Thompson made significant contributions to this 
report.  

FOOTNOTES 

[1] Cancer risk data from EPA's 1999 National-Scale Air Toxics 
Assessment, released in February 2006, estimates that more than 270 
million people in the United States are exposed at levels of risk that 
exceed 10 in 1 million due to the combined impacts of all sources of 
air toxics. This risk level implies that more than 10 persons out of a 
million may develop cancer if exposed continuously over their lifetime. 
Section 112 of the Clean Air Act identifies a lifetime cancer risk of 1 
in 1 million as a threshold above which regulation may be warranted for 
individual sources of air toxics, considering feasibility and costs. 

[2] The Clean Air Act refers to these substances as "hazardous air 
pollutants," which EPA uses interchangeably with the more common term 
"air toxics." In this report, we generally use the shorter term, air 
toxics. 

[3] We discuss the limitations of EPA's emissions data later in this 
report. 

[4] Major stationary sources are those that emit 10 or more tons per 
year of a single hazardous air pollutant or 25 or more tons per year of 
any combination of hazardous air pollutants. 

[5] The Clean Air Act refers to small stationary sources as "area 
sources." 

[6] In total, three chemicals and several substances from a listed 
group of chemicals have been removed from the list of air toxics 
originally provided in the 1990 amendments. By a joint resolution, 
Congress corrected the inadvertent addition of hydrogen sulfide to the 
substances originally listed in the 1990 amendments. EPA delisted 
caprolactam and methyl ethyl ketone. The agency also removed the 
compound ethylene glycol monobutyl ether (EGBE) and compounds called 
surfactant alcohol ethoxylates and their derivatives (SAED) from the 
listed glycol ethers category. The group glycol ethers is still listed. 

[7] See GAO, Air Pollution: EPA's Strategy and Resources May Be 
Inadequate to Control Air Toxics, GAO/RCED-91-143 (Washington, D.C.: 
June 26, 1991); Air Pollution: Progress and Problems in Implementing 
Selected Aspects of the Clean Air Act Amendments of 1990, GAO/ T-RCED-
94-68 (Washington, D.C.: Oct. 29, 1993); Air Pollution: Reductions in 
EPA's 1994 Air Quality Program's Budget, GAO/RCED-95-31BR (Washington, 
D.C.: Nov. 29, 1994); and Clean Air Rulemaking: Tracking System Would 
Help Measure Progress of Streamlining Initiatives, GAO/ RCED-95-70 
(Washington, D.C.: Mar. 2, 1995). 

[8] See GAO, Clean Air Act: EPA Has Completed Most of the Actions 
Required by the 1990 Amendments, but Many Were Completed Late, GAO-05-
613 (Washington, D.C.: May 27, 2005). 

[9] The National Academies, National Research Council, Air Quality 
Management in the United States (Washington, D.C., 2004). 

[10] EPA currently regulates 158 major source categories. Some 
industrial facilities may belong to multiple source categories. 

[11] MACT standards require all sources within a source category to 
control emissions to the same level. Existing sources generally must 
meet the average emission level achieved by the best performing 12 
percent of sources in the source category. New sources must meet a more 
stringent emission level. 

[12] EPA generally uses a lifetime cancer risk of 1 in 10,000 as the 
upper boundary of acceptability. As part of the ample margin of safety 
decision, EPA considers costs, technological feasibility, 
uncertainties, and other relevant factors. In this step, EPA must also 
assess whether to adopt more stringent standards to prevent adverse 
effects to wildlife, aquatic life, or natural resources considering 
cost, energy, and other relevant factors. 

[13] EPA was to promulgate regulations for small stationary sources 
listed under section 112(k) of the act by November 2000. Small 
stationary sources not listed under section 112(k) were subject to a 
different schedule. 

[14] U.S. Environmental Protection Agency, National Air Toxics Program: 
The Integrated Urban Strategy, Report to Congress (Research Triangle 
Park, North Carolina, 2000). 

[15] Among other things, the 2001 rule required refiners to maintain 
current levels of compliance with air toxic performance standards and 
did not require refiners to install new equipment or use technologies 
beyond those already in use. EPA did not set additional air toxics 
requirements for vehicles at that time because the agency had already 
established other standards for vehicles and fuels that it believed 
represented the greatest degree of toxics control achievable at that 
time. See Control of Hazardous Air Pollutants From Mobile Sources, 66 
Fed. Reg. 17229 (Mar. 29, 2001). 

[16] Control of Hazardous Air Pollutants from Mobile Sources, 71 Fed. 
Reg. 15804 (Mar. 29, 2006). 

[17] EPA officials cited the Toxics Release Inventory, various rules 
affecting motor vehicle fuel formulations, Design for the Environment, 
the Green Suppliers Network, and community-based initiatives such as 
Community Action for a Renewed Environment (CARE). 

[18] EPA applies the term "national cancer risk driver" to any air 
toxic that poses an estimated maximum lifetime cancer risk exceeding 10 
in 1 million to more than 25 million people. 

[19] See appendix II for information on our methodology for 
interviewing stakeholders. 

[20] The two challenges not rated as significant by any stakeholder 
groups were "complexity of required analyses to support regulatory 
actions" and "rigidity of Clean Air Act requirements." 

[21] U.S. Environmental Protection Agency, The Benefits and Costs of 
the Clean Air Act, 1970 to 1990 (Washington D.C., 1997); and The 
Benefits and Costs of the Clean Air Act, 1990 to 2010 (Washington D.C., 
1999). 

[22] EPA identified other key uncertainties with its cost analysis, 
including that the estimates were based on the costs of pollution 
control technologies that were available at the time and did not 
account for potential reductions in future costs due to technological 
innovation. 

[23] EPA has some dose-response data for benzene and plans to include 
the results of a case study assessing the benefits of reductions in 
benzene emissions in the Houston area in the next comprehensive 
assessment of Clean Air Act programs, which the agency expects to issue 
in 2007. 

[24] U.S. Environmental Protection Agency, Office of Inspector General, 
EPA's Method for Calculating Air Toxics Emissions for Reporting Results 
Needs Improvement (Washington, D.C., 2004). 

[25] U.S. Environmental Protection Agency, Office of Research and 
Development, Air Toxics Research Strategy (external review draft) 
(Washington, D.C., 2002). 

[26] U.S. Environmental Protection Agency, Office of Research and 
Development, Air Toxics Multi-Year Plan, (Washington, D.C., 2003). 

[27] U.S. Environmental Protection Agency, Science Advisory Board, 
EPA's Air Toxics Research Strategy and Air Toxics Multi-Year Plan 
(Washington, D.C., 2004). 

[28] The six priority air toxics include acrolein, arsenic, benzene, 
hexavalent chromium, formaldehyde, and 1,3 butadiene. EPA currently 
monitors for arsenic, benzene, hexavalent chromium, formaldehyde, and 
1,3 butadiene at all locations, and plans to monitor for acrolein at 
all locations beginning January 1, 2007. 

[29] U.S. Environmental Protection Agency, Office of Inspector General, 
Progress Made in Monitoring Ambient Air Toxics, But Further 
Improvements Can Increase Effectiveness (Washington, D.C., 2005). 

[30] According to EPA, a total of 4,271 facilities were required to 
comply with MACT standards as of 2004. 

[31] Establishing more stringent pollution control requirements 
generally involves trade-offs between regulatory costs and potential 
public health benefits. 

[32] New Jersey may also require some sources to conduct facilitywide 
risk assessments as part of the permitting process, but this is not a 
routine practice, according to a New Jersey program official. 

[33] The preamble to EPA's first final residual risk rule, the National 
Emission Standards for Coke Oven Batteries, 70 Fed. Reg. 19991, 19998 
(Apr. 15, 2005), articulates the agency's approach for evaluating 
remaining health risks from facilities regulated by MACT standards. EPA 
relied on this approach in its five final residual risk rules to date. 

[34] According to New Jersey officials, the program in that state does 
not routinely require sources to conduct facilitywide risk assessments. 
However, New Jersey's program may evaluate emissions from all emission 
points in a facility in a single risk assessment in situations where 
there is the potential for high risk. 

[35] As noted above, about 300 chemicals enter commerce each year. 

[36] For fiscal year 2006, EPA Region 4 included a grant commitment for 
the Louisville Metro Air Pollution Control District to submit its air 
toxics emission inventory as part of an air planning agreement to 
obtain federal funding for the local air program. EPA officials said 
that the agency's fiscal year 2007 grant guidance for state and local 
agencies does not require the submission of air toxics emissions 
inventories as a condition to obtain federal funding. 

[37] EPA, in its Consolidated Emissions Reporting Rule, 67 Fed. Reg. 
39602, 39604 (June 10, 2002), agreed with commenters and stated that it 
planned to develop air toxics reporting measures at a later date. 

[38] National Emission Standards for Hazardous Air Pollutants: Plywood 
and Composite Wood Products, 71 Fed. Reg. 8342 (Feb. 16, 2006). 

[39] Environmental Protection Agency, Compilation of Status Reports on 
the Implementation of Recommendations Made to EPA by the CAAAC on Air 
Quality Management (Washington, D.C., November 2005) 

[40] Results from nonprobability samples cannot be used to make 
inferences about a population, because in a nonprobability sample, some 
elements of the population being studied have no chance or an unknown 
chance of being selected as part of the sample. 

[41] California requires certain facilities to quantify and report 
emissions of 451 chemicals as part of its risk assessment program. In 
2006, the state may consider the addition of several hundred chemicals 
to the list of chemicals reported and used in risk assessments. Some 
facilities are also required to report the use or manufacture of 310 
additional chemicals for a potential total of 761 chemicals, but these 
chemicals are not currently considered in risk assessments. 

[42] The Oregon Department of Environmental Quality proposed to adopt 
benchmarks for 49 air toxics in February 2006. The benchmarks were not 
final as of the issue date of this report. 

[43] Wisconsin state law provides that Wisconsin's air toxics program 
does not apply to emissions that are regulated by federal MACT 
standards under section 112 of the Clean Air Act. 

[44] 71 FR 15832-15833, March 29, 2006. 

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