A
ir
Q
uAlity
M
AnAgeMent
in
the
u
nited
S
tAteS
T
he Clean Air Act (CAA) p r o v i d e s t h e l e g a l framework for promoting public health and public welfare by pursuing five major air quality goals (see Box 1). Individual states must develop state implementation plans (SIPs) that show how, with the assistance of national control programs, they will meet National Ambient Air Quality Standards (NAAQA) for six criteria pollutants. Such efforts, as well as those in pursuitof other CAA goals, seek to regulate emissions from a variety of stationary and mobile sources through the nation’s AQM system (see Figure 1, p. 2). Since passage of the CAA Amendments of 1970, the
nation has devoted signiicant efforts and resources
to AQM and substantial progress has been made.
Air Quality Management in the United States, a National Academies report, examines the role of science and technology in the implementation of the
CAA and recommends ways in which the scientiic
and technical foundations for AQM in the United States can be enhanced. Over a 2-year period, the
committee that authored the report heard brieings
from experts and stakeholders and examined the operation, successes, and limitations of the many components of the nation’s AQM system.
Progress To Date
Implementation of the Clean Air Act has contributed to substantial decreases in emissions of several pollutants. Regulations for light-duty vehicles, light-light-duty trucks, and fuel properties have greatly reduced emissions per mile traveled. Programs for stationary sources, such as power plants and large factories, have also achieved substantial reductions of pollutant emissions. However, most of the reductions have been accomplished through regulations on new facilities, while many older, often higher-emitting facilities can be a substantial source of emissions.
Emission “cap and trade” has also provided a mechanism for achieving emission reductions at reduced costs. Air quality monitoring networks have
conirmed that ambient pollutant concentrations,
especially in urban areas, have decreased over the past three decades, and monitoring has documented a reduction in sulfate deposition in the eastern United States. Economic assessments of the overall
costs and beneits of AQM in the United States
indicate, despite uncertainties, that implementation of the CAA has had and will probably continue to
have substantial net economic beneits.
Goals of the Clean Air Act
Mitigate potentially harmful ambient concentrations of six “criteria” pollutants: carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), particulate matter (PM), and lead (Pb).
Limit sources of exposure to hazardous air pollutants (HAPs).
Protect and improve visibility in wilderness areas and national parks.
Reduce emissions of substances that cause acid deposition, speciically sulfur dioxide andnitrogen oxides (NOx).
Challenges Ahead
Despite the progress, the report identiies scientiic
and technical limitations in the current AQM system that will hinder future progress, especially as the nation attempts to meet the following key challenges in the coming decade:
Meeting new standards for ozone, particulate matter, and regional haze.
Understanding and addressing the human health risks from exposure to air toxics.
Responding to the evidence that, for some pollutants, there may be no identifiable threshold exposure below which harmful effects cease to occur.
Mitigating pollution effects that might disproportionately occur in minority and low-income communities in densely populated urban areas.
Enhancing understanding and protection of ecosystems affected by air pollution.
Understanding and addressing multistate and international transport of pollutants.
Adapting the AQM system to a changing (and most likely warmer) climate.Long-Term Objectives
To meet these challenges and remedy current
limitations, the report identiies a set of overarching
EPA should strive to take an airshed-based approach to air quality management by assessing and control-ling pollutants arising from local, multistate, national and international sources. Photo courtesy NASA.
long-term objectives that should guide future improvement of the AQM system. AQM should work toward the following goals for the long term:
Strive to identify and assess more clearly the most significant exposures, risks, and uncertainties.
Strive to take an integrated multipollutant approach to controlling emissions of pollutantsposing the most signiicant risks.
Strive to take an airshed-based approach by assessing and controlling emissions of important pollutants arising from local, multistate, national, and international sources.
Strive to emphasize results over process, create accountability for the results, and dynamically adjust and correct the system as data on progress are assessed.Recommend Near Term Actions
Immediate attainment of these objectives is unrealistic. It would require a level of scientific understanding that has yet to be developed, a commitment
of new resources that would be dificult to obtain in the
short term, and a rapid transformation of the AQM system that is undesirable in light of the system’s past successes. The report proposes, therefore, that the AQM system be enhanced so that it steadily evolves toward meeting these objectives. In that spirit, the report makes
ive interrelated recommendations to be implemented through speciic actions:
1. (Highest Priority) Strengthen the scientiic and technical capacity of the AQM system to assess risk and track progress.
Critical actions include: enhancing or improving emissions tracking, air pollution monitoring, modeling, and exposure assessments; developing and implementing a system to assess and monitor human health and welfare effects; continuing to track implementation costs; and invest in research and human and technical resources.
2. Expand national and multistate performance-oriented control strategies to support local, state, and tribal efforts.
Critical actions include: expanding federal emission-control measures, especially for nonroad mobile sources, area sources, and building and consumer
products; emphasizing technology-neutral standards for emission control; using market-based approaches such as the SO2 emissions cap-and-trade program whenever practical and effective; reducing emissions from existing facilities and vehicles; and addressing multistate transport problems.
3. Transform the SIP process into a more dynamic and collaborative performance-oriented, multipollutant air quality management plan (AQMP) process.
Each state should be required to prepare an AQMP that integrates all relevant air quality measures, replacing all single pollutant SIPs with one comprehensive, multipollutant AQMP. Because these actions would
require signiicant changes in standard procedure at the
federal, state, and local level, it is recommended that
they occur in stages, over a deined transition period,
and possibly with incentives.
Substantial reforms are needed to focus on tracking results using periodic reviews, encouraging innovative strategies, retaining conformity with regional transportation plants, and retaining federal oversight (see box, p. 4)
4. Develop an integrated program for criteria pollutants and hazardous air pollutants (HAPs).
Critical actions include: developing a system to set priorities for those pollutants; instituting a dynamic
review of pollutant classiication; listing potentially
Committee on Air Quality Management in the United States: William Chameides(Chair), Georgia Institute of Technology, Atlanta, Daniel Greenbaum (Vice-Chair), Health Effects Institute, Boston, MA, Carmen Benkovitz, Brookhaven National Laboratory, Upton, NY, Eula Bingham, University of Cincinnati, Cincinnati, OH, Michael Bradley, M.J. Bradley & Associates, Concord, MA, Richard Burnett, Health Canada, Ottawa, Ontario, Dallas Burtraw, Resources for the Future, Washington, DC, Laurence Caretto, California State University, Northridge,
Costel Denson, University of Delaware, Newark, Charles Driscoll, Syracuse University, Syracuse, NY, Jane Hall, California State University, Fullerton, Philip Hopke, Clarkson University, Potsdam, NY, Arnold Howitt, Harvard University, Cambridge, MA, C.S. Kiang, Peking University, Beijing, China, Beverly Law,Oregon State University, Corvallis, James Lents, University of California, Riverside, Denise Mauzerall, Princeton University, Princeton, NJ, Thomas McGarity, University of Texas School of Law, Austin, Jana Milford, University of Colorado, Boulder, Michael Morris, North Central Texas Council of Governments, Arlington, Spyros Pandis, Carnegie Mellon University, Pittsburgh, PA, P. Barry Ryan, Emory University, Atlanta, GA, Adel Saroim, University of Utah, Salt Lake City, Sverre Vedal, National Jewish Medical and Research Center, Denver, CO,
Lauren Zeise, California Environmental Protection Agency, Oakland, Raymond Wassel (Study Director), Board on Environmental Studies and Toxicology.
This report brief was prepared by the National Research Council based on the committee’s report. For moreinformation, contact the Board on Environmental Studies and Toxicology at (202) 334-3060. Air Quality Management in the United States is available from the National Academies Press, 500 Fifth Street, NW, Washington, DC 20001; 800-624-6242 or 202-334-3313 (in the Washington area); www.nap.edu.
Permission granted to reproduce this brief in its entirety with no additions or alterations.
Copyright 2004 The National Academies 5. Enhance protection of ecosystems and other
aspects of public welfare.
Critical actions include: completing a comprehensive review of standards to protect public welfare; implementing networks for comprehensive ecosystem monitoring; establishing acceptable exposure levels for natural and managed ecosystems by evaluating data on the effects of air pollutants on ecosystems at least every 10 years; and promulgating secondary standards and tracking progress towards them, as well as considering regionally distinct standards.
Implementing these recommendations will require substantial resources, but they should not be overwhelming, especially compared with current expenditures for CAA compliance and costs resulting from harmful effects of air pollution on human health and welfare. Implementing these recommendations will also require a commitment by all parties to adjust and change; it may also require new legislation from Congress. As the transition occurs, it is imperative that ongoing programs to reduce emissions continue so that progress toward cleaner air is maintained.
Enhancing Agency Accountability and Performance
The overall goal of these recommendations is to foster a more collaborative and dynamic performance-oriented system, but experience has shown that not all states have equally addressed their air quality problems. Public accountability and performance could be enhanced through the following:
The Clean Air Act should continue to specify deadlines for attaining NAAQS milestones and to assess progress along the way; EPA should retain its authority to impose sanctions on states that fail to submit and implement adequate implementation plans.
States should not be sanctioned for failure of EPA to institute necessary regulations for multistate or national control programs that are beyond the states control.
Incentives should be created for states that meet or beat deadlines and for those that develop creative and effective multipollutant reduction strategies.
