Esworthy Specialist in Environmental Policy
Environmental Protection Agency (EPA) published its final revisions to the
Clean Air Act (CAA) National Ambient Air Quality Standards (NAAQS) for
particulate matter (particulates, or PM) on October 17, 2006. EPA’s
actions leading up to and following promulgation of the 2006 standard have
been the subject of considerable congressional oversight. EPA and states’
ongoing implementation of the standard, beginning with the designation of
those geographical areas not in compliance, likewise has been an area of
concern and debate among some Members of Congress, states, and other
stakeholders for some time. EPA’s most recent round of periodic review of the particulates
NAAQS and proposal to revise the PM NAAQS, published June 29, 2012, have prompted
further scrutiny of the ongoing implementation of the standards. EPA has agreed
to issue final revised PM NAAQS by December 14, 2012.
Promulgation of NAAQS sets in motion a process under which the states and EPA
identify areas that exceed the standard (“nonattainment areas”) using
multi-year air quality monitoring data and other criteria, requiring
states to take steps to reduce pollutant concentrations in order to achieve it.
The publication of the final designations for the 2006 NAAQS—and thus the
effective date of the final designations—had initially been delayed
pending review by the current Administration. On November 13, 2009, EPA
published its final designations for the 2006 PM NAAQS that included 120
counties and portions of counties in 18 states as nonattainment areas based on
2006 through 2008 air quality monitoring data. The final designations,
which include tribal land of 22 tribes, were effective as of December 14,
2009. States have three years from the effective date to submit
nonattainment area State Implementation Plans (SIPs), which identify specific
regulations and emission control requirements that would bring a
nonattainment area into compliance.
The 2006 NAAQS strengthened the pre-existing (1997) standard for “fine”
particulate matter 2.5 micrometers or less in diameter (PM2.5) by lowering
the allowable daily concentration of PM2.5 in the air. The daily
standard averaged over 24-hour periods was reduced from 65 micrograms per cubic
meter (μg/m3) to 35 μg/m3. However, the annual PM2.5 standard, which
addresses human health effects from chronic exposures to the pollutants,
was unchanged from the 1997 standard of 15 μg/m3. The 2006 NAAQS did not
substantially modify the daily standard for slightly larger, but still inhalable,
particles less than or equal to 10 micrometers (PM10), retaining the 24-hour standard
but revoking the annual standard for PM10.
EPA’s final nonattainment designations are only for the revised 2006 24-hour
PM2.5 standard. EPA did not require new nonattainment designations for
the PM2.5 annual standard and for PM10. The final designations for the
2006 PM2.5 NAAQS included a few areas designated nonattainment for PM2.5 for
the first time, but, as expected, the majority of the counties identified
overlapped with EPA’s final nonattainment designations for the 1997 PM2.5 NAAQS.
EPA’s designations for the 1997 PM2.5 NAAQS included all or part of 204
counties in 20 states and the District of Columbia. Most of them were only
exceeding the annual standard; only 12 counties were exceeding
both the 24-hour and the annual standards. Thus, the 2006
tightening of the 24-hour standard resulted in an increased number
of areas being designated nonattainment based on exceedances of both the 24-hour
and the annual standards.
Date of Report: October 25, 2012
Number of Pages: 41 Order Number: R40096 Price: $29.95
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