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CLEAN AIR ACT and Regulations


The Clean Air Act includes special provisions to help protect air quality in national parks and other federal lands. It gives federal land managers certain responsibilities and opportunities to participate in decisions being made by regulatory agencies that might affect air quality in federally-protected areas. A summary of the Clean Air Act -- highlighting these special provisions -- appears below.

•  Note: This summary is primarily drawn from: Ross, M. 1990. The Clean Air Act. Chapter 4 in M. A. Mantell, ed. Managing National Park System Resources: A Handbook of Legal Duties, Opportunities, and Tools. The Conservation Foundation, Washington , D. C. Republished with permission from the Conservation Foundation and the World Wildlife Fund.

The Clean Air Act in its entirety, the 1990 Amendments, legislative analyses and the Plain English Guide to the Clean Air Act can be accessed on EPA's website.

For EPA policy and guidance related to the Clean Air Act generally, please visit EPA's policy and guidance web page, which includes EPA guidance sorted by Clean Air Act title and recent EPA actions.


Air pollution can damage the very resources and values that the units of the National Park System were created to preserve. Research and monitoring already reveal that manmade air pollution affects all parks to some degree. For example, fine pollutant particles, especially sulfates, impair natural visibility in all parks. Higher than natural ozone concentrations injure sensitive vegetation in many parks. Acidic deposition alters the chemistry and biota in certain park aquatic systems. Acidic deposition and sulfur pollutants accelerate the decay of many park cultural resources.

The air pollution that affects parks can come from large, individual sources or, cumulatively, from many small or regional sources. It can originate from nearby or far-distant sources or anywhere in between. The one common ingredient is that the air pollution affecting parks originates largely outside parks and, therefore, beyond the National Park Service's management jurisdiction.

The Clean Air Act (CAA) provides some tools and many opportunities to protect park resources. In certain cases, the CAA gives the federal land manager a special role in regulatory decisions directly affecting park resources. In most other cases, the CAA provides opportunities to participate in the decision making that determines the quality of the air affecting parks. The CAA augments the fundamental resource-protection responsibilities of the National Park Service Organic Act with respect to air quality and related values in park areas. Together, these authorities form the basis for the park service's general policy of promoting and pursuing measures to safeguard park resources and values from the adverse impacts of air pollution.

The Structure of the Clean Air Act

The central goal of the CAA for the entire nation is safe and acceptable ambient air quality through the attainment and maintenance of "national ambient air quality standards." The "primary" standards are to protect the public health "with an adequate margin of safety" and the "secondary" standards are to protect the national "welfare" from all "known or anticipated adverse effects." The CAA defines the term "welfare" broadly to include virtually all the kinds of resources and values associated with park areas.

The primary and secondary standards are air pollutant concentrations set at protective levels on the basis of scientific "criteria documents. " The Environmental Protection Agency (EPA) has set national ambient air quality standards for six widespread pollutants; that is, sulfur dioxide, particulate matter, carbon monoxide, ozone, nitrogen dioxide, and lead. The CAA requires the EPA to review and, if appropriate, revise these standards no less often than every five years. State and local governments may set additional, and more stringent, standards.

At any time, a particular area may be "cleaner" or "dirtier" than the national standards for these pollutants. The CAA supplements its nationwide goal of attaining and maintaining these standards with specific goals for these "clean" and "dirty" areas. For the clean areas of the country, the CAA seeks to "prevent the significant deterioration" (PSD) of the air quality, particularly in areas of special natural, recreational, scenic, or historic value. It also seeks to protect the special visibility values of certain clean air areas, for example, the scenic qualities of many parks. For the "dirty" or "nonattainment" areas of the country, the CAA demands that "reasonable further progress" be made toward the attainment and maintenance of the primary and secondary standards, including attainment of the primary health standards by specified deadlines and attainment of the secondary welfare standards "as expeditiously as possible."


Typically, the measures used by the CAA to pursue its several goals are various performance and emission restrictions on individual sources. In other words, the CAA generally attempts to control overall pollution levels by limiting the amount of pollution emitted into the air by specific sources. These requirements are sometimes technology-forcing, in that they encourage both the general growth of the pollution technology industry and specific applications of advanced technology to individual sources. Examples of the CAA's performance and emissions restrictions read like an alphabet soup of regulatory jargon: NSPS (new source performance standards), NESHAPS (national emission standards for hazardous air pollutants), BACT (best available control technology), BART (best available retrofit technology), RACT (reasonably available control technology), LAER (lowest achievable emission rate), and FMVCP (federal motor vehicle control program).


The CAA uses the State Implementation Plan (SIP) process as the principal means for implementing and enforcing its goals and its source restrictions. In brief, the SIP is a plan devised by the state and approved by EPA with source-specific measures for carrying out the CAA. For example, these plans can include specific emission limitations, transportation controls, and economic incentives for reducing pollution. Through the SIP, the state can allocate its air resource. States may always include measures more stringent than the federal requirements.

Parks and the Clean Air Act

Throughout each aspect of the CAA's structure-its goals, measures, and means-are numerous opportunities to influence a regulatory agency's action to protect the air quality and related values of parks. Examples of regulatory actions that can affect park air quality protection significantly are the determination of national ambient air quality standards, control technology requirements, state implementation measures, and individual source permits. All of the CAA's regulatory actions involve notice to the public of proposed actions and opportunity for comment. Many provisions require consultation with affected federal land managers, and certain provisions give additional influence to the federal land manager's opinion. Generally, the better the National Park Service's scientific information on the sources and effects of air pollution affecting parks, the more influential the service can be on proposed regulatory actions. By taking advantage of these opportunities, the park service can ensure that EPA and applicable state agencies consider the special benefits and costs of their regulatory decisions with respect to park air quality and related values.

Additional References:

Malkin, K. 1994. Clean Air Act. Pp. 28-32 in N. Shelton and L. Fox, eds. An Introduction to Selected Laws Important for Resources Management in the National Park Service. Natural Resources Report NPS/NRPO/NRR-94/15. U.S. Department of the Interior, National Park Service, Natural Resources Publication Office.

updated on 11/02/2006  I   http://nature.nps.gov/air/Regs/cleanAir.cfm   I  Email: Webmaster