Legal Lookout: EPA Staff Urges Changes in PM Standards

Earlier this year, EPA staff scientists urged agency management to revise the current particulate matter (PM) standards for fine particles and the inhalable portion of coarse particles, based on evidence that suggests to EPA scientists that more protection is needed than is provided under current air standards.

The Clean Air Act (CAA) requires that EPA periodically review its National Ambient Air Quality Standards. EPA has established primary and secondary air standards under the CAA. Primary standards are those designed to protect public health with an adequate margin of safety. Secondary standards are designed to protect against so-called “welfare” effects, including ecological damage, visibility impairment (haze), and damage to materials. The air quality standards for PM were first established in 1971. The agency significantly changed the standards in 1987, when they changed the indicator of the standards to regulate inhalable particles smaller than, or equal to, 10 micrometers in diameter.
In 1997, EPA again revised the PM standards and established a separate standard for fine particles (PM2.5). This new standard was based on EPA’s conclusion that fine particles can give rise to adverse health effects, especially those adversely impacting the heart and lungs. PM10 standards were also revised to address inhalable coarse particles ranging from 2.5 to 10 micrometers in diameter.
Shortly after the 1997 standards were issued, the American Trucking Association sued EPA. The U.S. Court of Appeals for the D.C. Circuit ruled in 1999 that EPA had overstepped its authority in establishing a new public health air quality standard for both PM and ozone.[1] Although the court left the standards in place, it ruled they were not enforceable. The court also vacated the revisions to the PM10 standard, concluding that PM10 was not a defensible measure of coarse particles because it includes fine particles.
EPA appealed the decision, and in 2001, the Supreme Court upheld EPA’s authority to set air quality standards and affirmed that the CAA does not allow the agency to consider costs when setting air standards. The decision also required that the agency set standards at levels necessary to protect public health with an adequate margin of safety and to protect the public welfare from adverse effects.[2]
As part of EPA’s periodic review of air quality standards, EPA must thoroughly reassess the adequacy of existing air standards. The review, which is intended to be quite comprehensive, is conducted through EPA’s Office of Research and Development (ORD) and the Office of Air and Radiation. The first step in the review process is ORD’s development of an air quality criteria document, which represents the compilation and evaluation of the most recent scientific knowledge useful for purposes of assessing the health effects of the air pollutant/standard being considered. EPA must consider as part of this process any advice offered by the Clean Air Scientific Advisory Committee (CASAC). CASAC was created under the CAA and is part of EPA’s Science Advisory Board, which is an independent scientific panel that offers technical advice and recommendations to EPA on various topics.
Public comment is also solicited. EPA thereafter prepares a staff paper based on all three sources of information: the criteria document, CASAC comment and public comment. The staff paper represents the assessment, conclusions and recommendations of EPA scientists and staff. It contains the scientific judgments of the EPA professionals presenting them, and is not intended to represent EPA decisions.

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