Ozone Air Quality Standards: EPA’s Proposed Revisions Page: 4 of 15
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Ozone Air Quality Standards: EPA's Proposed Revisions
On January 19, 2010, the Environmental Protection Agency (EPA) proposed revisions to the
National Ambient Air Quality Standards (NAAQS) for ozone.' Because they have widespread
implications for public health and for the pollution control measures that will be imposed on
sectors of the economy, the revisions have stirred congressional interest and caused a variety of
reactions among state and local officials. EPA held three public hearings (in Arlington, VA,
Houston, TX, and Sacramento, CA) during the first week of February 2010, and accepted public
comments in writing until March 22. The agency received more than 5,000 unique comments.
Final standards were expected to be issued by the end of August 2010, but EPA has delayed
promulgation, first to October, then to December, and now to July 2011. The delays have allowed
the agency to analyze the information it received during the public comment period. Having done
so, the agency says that it intends to seek additional advice from the Clean Air Scientific
Advisory Committee (CASAC), a panel of outside experts who review agency decision-making
regarding the setting of NAAQS. Specifically, the agency intends to take the following steps:
During December 2010 and January 2011, EPA intends to prepare a set of questions for
CASAC and provide them for CASAC's review. The questions are expected to request
additional advice focused on the scientific evidence and other information before the
Administrator. EPA anticipates that CASAC will hold a public meeting in February 2011 to
discuss their response, and anticipates that CASAC will provide its additional advice to the
Agency by letter shortly thereafter. The CASAC process includes an opportunity for the
public to submit comments to CASAC and EPA. EPA intends to issue a final decision on the
reconsideration by July 29, 2011.2
The final decision will be subject to interagency review under Executive Order No. 12866 before
This report provides background on NAAQS, the process used to establish them, the pre-existing
ozone standards, and EPA's proposed revisions, as well as information regarding the revisions'
What Are NAAQS?
As defined in Section 109 of the Clean Air Act, NAAQS are standards that apply to ambient
(outdoor) air. The act directs EPA to set both primary and secondary standards. Primary NAAQS
are standards, "the attainment and maintenance of which in the judgment of the [EPA]
Administrator .. . are requisite to protect the public health,"~ with ''an adequate margin of safety.''
Secondary NAAQS are standards necessary to protect public welfare, a broad term that includes
damage to crops, vegetation, property, building materials, etc.'
1 75 Federal Register 2938.
2 Declaration of Regina McCarthy, Assistant Administrator for Air and Radiation, Environmental Protection Agency,
December 8, 2010, State of Mississippi v. EPA, Document 1281979, D.C. Cir. No. 08-1200.
3~ The Clean Air Act's definition of welfare is found in Section 302(h) of the act (42 U.S.C. 7602).
Congressional Research Service1
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Ozone Air Quality Standards: EPA’s Proposed Revisions, report, December 21, 2010; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc821316/m1/4/: accessed December 11, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.