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###### Environmental Protection Agency

          - [EPA-HQ-OAR-2007-0352; FRL-8936-9]

# AGENCY:

Environmental Protection Agency (EPA).

# ACTION:

Notice of availability of final report.

# SUMMARY:

                        On or about July 31, 2009, the Office of Air Quality Planning and Standards (OAQPS) of EPA is making available a final report,                         *Risk and Exposure Assessment to Support the Review of the SO*2*Primary National Ambient Air Quality Standard: Final Report.*                         This document presents the approaches taken to assess exposures to ambient SO2                         and to characterize associated health risks, and presents the results of those assessments. This document also contains a staff policy assessment regarding the adequacy of the current SO2                         NAAQS and potential alternative primary SO2                         standards.                    

# FOR FURTHER INFORMATION CONTACT:

                        Dr. Michael J. Stewart, Office of Air Quality Planning and Standards (Mail Code C504-06), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; e-mail:                         *stewart.michael@epa.gov;*                         telephone: 919-541-7524; 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-2007-0352. Publicly available docket materials are available either electronically through                     *http://www.regulations.gov*                     or in hard copy at the EPA Docket Center (EPA/DC), EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket Center Public Reading 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 this                     **Federal Register**                     document electronically through the EPA Internet under the “                    **Federal Register”**                     listings at                     *http://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                           ( print page 37706)                        periodically review and, if appropriate, revise the NAAQS based on the revised criteria.                

                    Air quality criteria have been established for sulfur oxides (SOX) and NAAQS have been established for sulfur dioxide (SO2), an indicator for gaseous SOX                    . Presently, EPA is in the process of reviewing the NAAQS for SO2                    . As part of its review of the NAAQS, EPA prepared an assessment of exposures and health risks associated with ambient SO2. A plan describing the proposed approaches to assessing exposures and risks was described in                     *Sulfur Dioxide Health Assessment Plan: Scope and Methods for Exposure and Risk Assessment.*                     This document was released for public review and comment in November 2007 and was the subject of a consultation with the Clean Air Scientific Advisory Committee (CASAC) on December 5-6, 2007. Comments received from that consultation were considered in developing a draft document,                     *Risk and Exposure Assessment to Support the Review of the SO**2**Primary National Ambient Air Quality Standard: First Draft,*                     which was released for public review and comment in July 2008 and was the subject of a CASAC review on July 30-31, 2008. Comments received from that review were considered in developing a second draft document,                     *Risk and Exposure Assessment to Support the Review of the SO**2**Primary National Ambient Air Quality Standard: Second Draft,*                     which was released for public review and comment in March 2009 and was the subject of a CASAC review on April 16-17, 2009. In preparing the final risk and exposure assessment report, EPA considered comments received from CASAC and the public at and subsequent to that meeting.                

                    The                     *Risk and Exposure Assessment to Support the Review of the SO**2**Primary National Ambient Air Quality Standard: Final Report*                     being released at this time conveys the approaches taken to assess exposures to ambient SO2                     and to characterize associated health risks, and presents the results of those assessments. This document also contains a staff policy assessment that considers the health evidence presented in an EPA document,                     *Integrated Science Assessment for Oxides of Sulfur*                     (available at:                     *http://www.epa.gov/​ttn/​naaqs/​standards/​so2/​s_​so2_​cr_​isa.html*                    ), and the exposure and risk characterization results, as they relate to the adequacy of the current SO2                     NAAQS and consideration of potential alternative primary SO2                     standards. The                     *Risk and Exposure Assessment to Support the Review of the SO**2**Primary National Ambient Air Quality Standard: Final Report*                     will be available online at:                     *http://www.epa.gov/​ttn/​naaqs/​standards/​so2/​s_​so2_​cr_​rea.html.*

Dated: July 22, 2009.

Jenny Noonan Edmonds,

Acting Director, Office of Air Quality Planning and Standards.

[FR Doc. E9-18005 Filed 7-28-09; 8:45 am]

BILLING CODE 6560-50-P