2010 Progress Report - International Joint Commission

emissions have also been successful in a number of
cities. Together, these programs have led to important
reductions in particle pollution in the United States.
Through 2009, 35 of the 39 designated nonattainment
areas have air quality concentrations attaining the
1997 PM 2.5
standards.
In October 2006, the EPA completed another review
of the PM standards, refl ecting fi ndings from scientifi c
studies published since the last review. The level
of the annual PM 2.5
standard remained unchanged
at 15 μg/m 3 . However, the EPA established a more
protective 24-hour standard at 35 μg/m 3 (average of
98 th percentile values for 3 years). The secondary
standards were set at levels identical to those for
the primary standards. The existing 24-hour PM 10
standard of 150 μg/m 3 was retained. However, due
to a lack of evidence linking health problems to
long-term exposure to coarse particle pollution, the
EPA revoked the annual PM 10
standard. The revised
standards and related information can be found at
www.epa.gov/pm/standards.html.
Following the issuance of the 2006 standards, a
number of parties challenged the EPA’s decision not
to strengthen the annual standard as recommended
by the CASAC. In February 2009, a federal appellate
court remanded the 2006 annual standard back to the
EPA. The EPA intends to address the remand of the
annual standard in the context of the ongoing review
of the PM standards, scheduled for completion in late
2011. More information on the current PM NAAQS
review can be found at www.epa.gov/ttn/naaqs/
standards/pm/s_pm_index.html.
Following the revision of the 24-hour PM 2.5
standards in
2006, the EPA designated 31 areas as nonattainment
areas for the new standard in November 2009. Sixteen
of these areas had been designated nonattainment
for PM 2.5
in 2005; 15 areas were new PM 2.5
nonattainment areas. In contrast to the previous round
of nonattainment designations in 2005, a number of
the new areas have high concentrations primarily
in the cold weather months, with key contributions
from wood smoke emissions. State attainment
plans for these 31 nonattainment areas are due in
December 2012. Additional information on the 2009
area designations can be found at www.epa.gov/
pmdesignations/2006standards/.
Commitments
41