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###### Environmental Protection Agency

          - [EPA-HQ-OAR-2007-1145; FRL-8959-6]

# AGENCY:

Environmental Protection Agency (EPA).

# ACTION:

Notice of availability of final report.

# SUMMARY:

                        On or about September 15, 2009, the Office of Air Quality Planning and Standards (OAQPS) of EPA is making available a final report,                         *Risk and Exposure Assessment for Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Final Report.*                         The purpose of this document is to convey the approach taken to assess environmental exposures to ambient oxides of nitrogen and sulfur and to characterize associated public welfare risks, as well as to present the results of those assessments.                    

# FOR FURTHER INFORMATION CONTACT:

                        Dr. Anne Rea, Office of Air Quality Planning and Standards (Mail code C539-02), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711;                         *e-mail: rea.anne@epa.gov; telephone:*                         919-541-0053;                         *fax:*                         919-541-0840.                    

## 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-2007-1145. 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 periodically review and revise the NAAQS, if appropriate, based on the revised criteria.

                        The EPA is currently conducting a joint review of the existing secondary (welfare-based) NAAQS for oxides of nitrogen (NOX) and oxides of sulfur (SOX). Because NOX, SOX, and their associated transformation products are linked from an atmospheric chemistry perspective as well as from an environmental effects perspective, and because of the National Research Council's (NRC's) 2004 recommendations to consider multiple pollutants in forming the scientific basis for the NAAQS, EPA has decided to jointly assess the science, risks, and policies relevant to protecting the public welfare associated with oxides of nitrogen and oxides of sulfur. This is the first time since NAAQS were established in 1971 that a joint review of these two pollutants has been conducted. Since both the Clean Air Scientific Advisory Committee (CASAC) and EPA have recognized these interactions historically, and the science related to these interactions has continued to evolve and grow to the present day, there is a strong basis for considering them together.                    

                        As part of its review of the secondary NAAQS for NOX                         and SOX, EPA is preparing an assessment of exposures and characterization of risks for adverse ecological effects associated with atmospheric NOX                         and SOX                         deposition. A draft plan describing the proposed approaches to assessing ecological exposures and effects is described in the draft document,                         *Draft Scope and Methods Plan for Risk/Exposure Assessment: Secondary NAAQS Review for Oxides of Nitrogen and Oxides of Sulfur.*                         This document was released for public review and comment in March 2008 and was the subject of a consultation with the CASAC on April 2 and 3, 2008. Comments received from that consultation were considered in developing the document titled,                         *Risk and Exposure Assessment to Support the Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: First Draft,*                         which was released for public review and comment in August 2008. This document was the subject of a CASAC review on October 1-2, 2008. Comments received from that review were considered in developing the document titled,                         *Risk and Exposure Assessment to Support the Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Second Draft,*                         which was released for public review and comment in June 2009 and was the subject of a CASAC review on July 22-23, 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 for Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Final Report*                         being released at this time conveys the approach taken to assess ecological effects due to the deposition of ambient NOX                         and SOX,      ( print page 48544)                            and presents the results of these analyses. This document will be available online at:                         *http://www.epa.gov/​ttn/​naaqs/​standards/​no2so2sec/​cr_​rea.html.*

Dated: September 14, 2009.

Jennifer Noonan Edmonds, 

Acting Director, Office of Air Quality Planning and Standards.

[FR Doc. E9-22951 Filed 9-22-09; 8:45 am]

BILLING CODE 6560-50-P