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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OAR-2006-0922; FRL-8748-5]

Final Risk and Exposure Assessment Report for Nitrogen Dioxide (NO2)

AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of availability of final report.
SUMMARY: On November 21, 2008, the Office of Air Quality Planning and Standards (OAQPS) of EPA made available a final report titled,Risk and Exposure Assessment to Support the Review of the NO 2 Primary National Ambient Air Quality Standard: Final Report.This final report has two primary purposes. The first is to convey the approaches taken to characterize human exposures and health risks associated with ambient NO2and to present the results of these analyses. The second is to present a discussion of the NO2scientific evidence and the exposure- and risk-based information specifically as it relates to the current and potential alternative NO2standards.
FOR FURTHER INFORMATION CONTACT: Dr. Scott Jenkins, Office of Air Quality Planning and Standards (Mail Code C504-06), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; e-mail:Jenkins.scott@epa.gov;telephone: 919-541-1167; fax: 919-541-0237.
SUPPLEMENTARY INFORMATION: General Information A. How Can I Get Copies of This Document and Other Related Information

1.Docket.EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2006-0922. Publicly available docket materials are available either electronically throughhttp://www.regulations.govor in hard copy at the EPA Docket Center (EPA/DC), EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket Center PublicReading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Office of Air and Radiation Docket is (202) 566-1742.

2.Electronic Access.You may access thisFederal Registerdocument electronically through the EPA Internet under theFederal Registerlistings athttp://www.epa.gov/fedrgstr/.

Under section 108(a) of the Clean Air Act (CAA), the Administrator identifies and lists certain pollutants which “cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.” The EPA then issues air quality criteria for listed pollutants, which are commonly referred to as “criteria pollutants.” The air quality criteria are to “accurately reflect the latest scientific knowledge useful in indicating the kind and extent of all identifiable effects on public health or welfare which may be expected from the presence of [a] pollutant in the ambient air, in varying quantities.” Under section 109 of the CAA, EPA establishes national ambient air quality standards (NAAQS) for each listed pollutant, with the NAAQS based on the air quality criteria. Section 109(d) of the CAA requires periodic review and, if appropriate, revision of existing air quality criteria. The revised air quality criteria reflect advances in scientific knowledge on the effects of the pollutant on public health or welfare. The EPA is also required to periodically review and revise the NAAQS, if appropriate, based on the revised criteria.

Air quality criteria have been established for the nitrogen oxides (NOX) and NAAQS have been established for nitrogen dioxide (NO2), an indicator for gaseous NOX. Presently, EPA is in the process of reviewing the NAAQS for NO2. As part of its review of the NAAQS, EPA prepared an assessment of exposures and health risks associated with ambient NO2. A draft plan describing the proposed approaches to assessing exposures and risks is described in the draft document,Nitrogen Dioxide Health Assessment Plan: Scope and Methods for Exposure and Risk Assessment.This document was released for public review and comment in September, 2007 and was the subject of a consultation with the Clean Air Scientific Advisory Committee (CASAC) on October 24 and 25, 2007. Comments received from that consultation were considered in developing the document titled,Risk and Exposure Assessment to Support the Review of the NO 2 Primary National Ambient Air Quality Standard: First Draft,which was released for public review and comment in April 2008. This document was the subject of a CASAC review on May 1 and 2, 2008. Comments received from that review were considered in developing the document titled,Risk and Exposure Assessment to Support the Review of the NO 2 Primary National Ambient Air Quality Standard: Second Draft,which was released for public review and comment in two parts, the first in August, 2008 and the second in October, 2008. This document was the subject of CASAC reviews on May 1 and 2, 2008 and on October 22, 2008. In preparing the final risk and exposure assessment report, EPA has considered comments received from the CASAC and the public at those meetings.

This final report has two primary purposes. The first is to convey the approaches taken to characterize human exposures and health risks associated with ambient NO2and to present the results of these analyses. The second is to present a discussion of the NO2scientific evidence and the exposure- and risk-based information specifically as it relates to the current and potential alternative NO2standards. This final document is available online at:http://www.epa.gov/ttn/naaqs/standards/nox/s_nox_cr_rea.html.

Dated: December 1, 2008. Mary E. Henigin, Acting Director, Office of Air Quality Planning and Standards.