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###### Environmental Protection Agency

          - [EPA-HQ-OAR-2008-0015; FRL-9159-4] 

# AGENCY:

Environmental Protection Agency (EPA). 

# ACTION:

Notice of Availability.

# SUMMARY:

                        The Office of Air Quality Planning and Standards (OAQPS) of EPA is announcing the availability of a final document titled,                         *Quantitative Risk and Exposure Assessment for Carbon Monoxide*                         (REA). The REA describes                               ( print page 32179)                            quantitative analyses that have been conducted as part of the review of the National Ambient Air Quality Standards (NAAQS) for carbon monoxide (CO).                     

# DATES:

The REA will be available on or about May 28, 2010. 

# ADDRESSES:

                        The document will be available primarily via the Internet at the following Web site:                         *http://www.epa.gov/​ttn/​naaqs/​standards/​co/​s_​co_​index.html.*

# FOR FURTHER INFORMATION CONTACT:

                        For questions related to this document, please contact Dr. Deirdre Murphy, Office of Air Quality Planning and Standards (Mail code C504-06), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; e-mail:                         *murphy.deirdre@epa.gov;*                         telephone: 919-541-0729; fax: 919-541-0237.                     

# SUPPLEMENTARY INFORMATION:

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 these 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 primary (health-based) and secondary (welfare-based) NAAQS for pollutants for which air quality criteria are issued. 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. 

                    Presently, EPA is reviewing the NAAQS for CO. The EPA's overall plan and schedule for this review is presented in the                     *Plan for Review of the National Ambient Air Quality Standards for Carbon Monoxide.*[1]                                          A draft of this integrated review plan was released for public review and comment in March 2008 and was the subject of a consultation with the Clean Air Scientific Advisory Committee (CASAC) on April 8, 2008 (73 FR 12998). Comments received from that consultation and from the public were considered in finalizing the plan for the review.                 

                    As part of EPA's review of the primary (health-based) CO NAAQS, the Agency has conducted qualitative and quantitative assessments characterizing the health risks associated with exposure to ambient CO. The EPA's plans for conducting these assessments, including the proposed scope and methods of the analyses, were presented in a planning document titled,                     *Carbon Monoxide National Ambient Air Quality Standards: Scope and Methods Plan for Health Risk and Exposure Assessment*                     (Scope and Methods Plan). This planning document was released for public comment in April 2009 and was the subject of a consultation with the CASAC on May 13, 2009 (74 FR 15265). First and second external review drafts of the REA were released for CASAC review and public comment in October 2009 (74 FR 55843) and February 2010 (75 FR 10252), respectively, and were the subjects of CASAC review meetings in November 2009 (74 FR 54042) and March 2010 (75 FR 9206), respectively. In preparing the final REA, EPA has considered comments received from CASAC and the public on these earlier draft documents. The REA document announced today conveys the approaches taken to assess exposures to ambient CO and to characterize associated health risks, as well as presents key results, observations, and related uncertainties associated with the quantitative analyses performed. This document will be available on or about May 28, 2010, through the Agency's Technology Transfer Network (TTN) Web site at                     *http://www.epa.gov/​ttn/​naaqs/​standards/​co/​s_​co_​index.html.*                     This document may be accessed in the “Documents from Current Review” section under “Risk and Exposure Assessments.”                 

Dated: May 27, 2010. 

Jennifer Noonan Edmonds, 

Acting Director, Office of Air Quality Planning and Standards.

# Footnotes

1.                             EPA 452R-08-005; August 2008; Available:                         *http://www.epa.gov/​ttn/​naaqs/​standards/​co/​s_​co_​cr_​pd.html.*
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[FR Doc. 2010-13620 Filed 6-4-10; 8:45 am] 

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