Ozone and PM 2.5 Air Standards
September 1, 1999
As previously reported, on May 14, the U.S. Court of Appeals for the District
of Columbia held that EPA exceeded its delegated authority in 1997 when it
promulgated revised ozone and particulate matter (PM) air quality standards
under section 104 of the Clean Air Act (CAA). The court held that EPA failed to
adequately justify or explain why the particular protection levels reflected in
the standards were set and remanded the standards to EPA.
The court vacated the revisions to the PM-10 standard, but not the new
eight-hour ozone standard, and on June 18, decided not to vacate the PM 2.5
standard. The court did not vacate the ozone and PM 2.5 standards because states
are not required to implement those standards until after 2000, so they cannot
be enforced. The court has also stayed State Implementation Plan (SIP) deadlines
for implementing the remanded standards. On June 28, the Department of Justice
and EPA filed a petition for rehearing of the appellate court's decision.
In related action, on April 30, EPA took final action on Section 126
petitions filed by eight Northeastern states that seek to mitigate the transport
of nitrogen oxides (NOx) across state boundaries. The section 126 petitions
claim that NOx transported across state lines prevented the states from
attaining the federal ozone standards (NOx are primary precursors of
ground-level ozone). The April 30 action called for implementation of NOx
controls under section 126 of the CAA. On May 25, the appellate court delayed
implementation of EPA's September 1998 "NOx SIP call," which imposed a
September 1999 deadline for affected states to submit SIPs to reduce NOx and
ozone transport.
On June 24, EPA stayed the effective date of the April 30 final determination
and issued an interim rule in order to allow EPA time to develop and propose
stand-alone regulations for controlling NOx emissions in 12 Midwestern states
and the District of Columbia, which were determined to be contributing to ozone
violations in the eight Northeastern states. The April 30 rule determined that
the following states were contributing to ozone violations in the eight
Northeastern states that filed petitions: Delaware, Indiana, Kentucky, Maryland,
Michigan, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Virginia,
West Virginia and the District of Columbia. Under the new interim rule, these
jurisdictions must implement necessary controls by 2003 that will reduce NOx
emissions under the existing one-hour ozone standard.
The temporary stay of the April 30 determination is effective from July 26 to
November 30, 1999.