The Congressional Research Service (CRS), the public policy research arm of Congress, recently issued the report The National Ambient Air Quality Standards (NAAQS) for Particulate Matter (PM): EPA’s 2006 Revisions and Associated Issues (Mar. 14, 2013). The 31-page report authored by Robert Esworthy discusses the following:
Summary
On October 17, 2006, the Environmental Protection Agency (EPA) published
its final revisions to the National Ambient Air Quality Standards (NAAQS) for
particulate matter (particulates, or PM). Several states and industry,
agriculture, business, and environmental and public health advocacy groups
petitioned the U.S. Court of Appeals for the District of Columbia Circuit, challenging
certain aspects of EPA’s revisions. A February 24, 2009, decision by the D.C.
Circuit granted the petitions in part, denying other challenges, and remanded
the standards to EPA for further consideration but did not specifically vacate
the 2006 PM standards. EPA initiated its next round of the periodic review of
the PM NAAQS, in part, in response to the court’s decision and on June 29,
2012, published a proposal to strengthen the standards. These actions, and the ongoing
implementation of the 2006 PM NAAQS, have prompted renewed interest among Members
of Congress.
Experiences
and issues leading up to and following the promulgation of the 2006 PM2.5 NAAQS
could provide relevant insights as EPA proceeds with its current review.
Although a tightening of the standards, the particulates NAAQS established in
2006 were not as stringent as recommended by EPA staff or the independent
scientific advisory committee mandated under the Clean Air Act (Clean Air
Scientific Advisory Committee, or CASAC). The divergence from the CASAC’s recommendations
proved controversial, as did several other elements of the 2006 particulates NAAQS,
including the decision not to exclude rural sources from the coarse particle
standard.
EPA
found that the evidence continued to support associations between exposure to
particulates in ambient air and numerous health problems. Based on several
analytical approaches, EPA estimated that compliance with the revised NAAQS
would prevent 1,200 to 13,000 premature deaths annually, as well as substantial
numbers of hospital admissions and missed work days due to illness. EPA revised
the PM NAAQS by strengthening the 1997 standard for “fine” particulate matter
2.5 micrometers or less in diameter (PM2.5). Specifically, the agency lowered
the allowable daily concentration averaged over 24-hour periods of PM2.5 in
the air from 65 micrograms per cubic meter (μg/m3) to 35 μg/m3. The
annual PM2.5 standard, which is set in addition to the daily standard to
address human health effects from chronic exposures to the pollutants, was
unchanged from the 1997 standard. The decision not to tighten the annual
standard was overturned by the D.C. Circuit and remanded to EPA for
consideration.
The
2006 particulates NAAQS also retained the 24-hour standard and revoked the
annual standard for slightly larger, but still inhalable, particles less than
or equal to 10 micrometers (PM10). EPA abandoned its proposal to
replace the particle size indicator of PM10 with a range of 10 to 2.5
micrometers (PM10-2.5). The D.C. Circuit’s February 24, 2009, decision upheld EPA’s decisions
with regard to PM10 NAAQS.
EPA’s
ongoing implementation of the 2006 NAAQS, including EPA’s November 13, 2009,
final designation of those geographical areas not in compliance (typically
defined by counties or portions of counties), has been an area of debate among
some Members of Congress, states, and other stakeholders. Although EPA did not
require new nonattainment designations for PM10, the tightening of the PM2.5 standard
resulted in an increased number of areas in nonattainment compared to the
designations for the 1997 PM NAAQS. EPA’s November 2009 final designations for
the 2006 PM NAAQS included 120 counties and portions of counties in 18 states
as nonattainment areas based on 2006 through 2008 air quality monitoring data.
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