E9-11917. Second Draft Risk and Exposure Assessment Report for Sulfur Dioxide (SO2

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice of extension of comment period.

SUMMARY:

The EPA is announcing an extension of the public comment period for the draft document titled “Risk and Exposure Assessment to Support the Review of the SO₂ Primary National Ambient Air Quality Standards: Second Draft” (74 FR 18573). The EPA is extending the comment period that originally ends on May 20, 2009. The extended comment period will close on June 11, 2009. The EPA is extending the comment period to provide stakeholders and the public with adequate time to conduct appropriate analysis and prepare meaningful comments.

DATES:

Comments on the above report must be received on or before June 11, 2009.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2007-0352, by one of the following methods:

• http://www.regulations.gov: Follow the on-line instructions for submitting comments.
• E-mail: Comments may be sent by electronic mail (e-mail) to [e-mail], Attention Docket ID No. EPA-HQ-OAR-2007-0352.
• Fax: Fax your comments to 202-566-9744, Attention Docket ID. No. EPA-HQ-OAR-2007-0352.
• Mail: Send your comments to: Air and Radiation Docket and Information Center, Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention Docket ID No. EPA-HQ-OAR-2007-0352.
• Hand Delivery or Courier: Deliver your comments to: EPA Docket Center, 1301 Constitution Ave., NW., Room 3334, Washington, DC. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-2007-0352. The EPA's policy is that all comments received will be included in the public docket without change and may be made available online at http://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through http://www.regulations.gov, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at http://www.epa.gov/​epahome/​dockets.htm.

Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in http://www.regulations.gov or in hard copy at the Air Docket in the EPA Docket Center, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. This Docket Facility is open from 8:30 a.m. to 4:30 p.m. Monday through Friday, excluding legal holidays. The Docket telephone number is 202-566-1742; fax [phone].

FOR FURTHER INFORMATION CONTACT:

Dr. Michael Stewart, Office of Air Quality Planning and Standards (Mailcode C504-06), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; e-mail: [e-mail]; telephone: [phone]; fax: [phone].

General Information

A. What Should I Consider as I Prepare My Comments for EPA?

1. Submitting CBI. Do not submit this information to EPA through http://www.regulations.gov or e-mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM as CBI and then identify electronically within the disk or CD-ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.

2. Tips for Preparing Your Comments. When submitting comments, remember to:

• Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date and page number).
• Follow directions—The agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.
• Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes.
• Describe any assumptions and provide any technical information and/or data that you used.
• If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced.
• Provide specific examples to illustrate your concerns, and suggest alternatives.
• Explain your views as clearly as possible, avoiding the use of profanity or personal threats.
• Make sure to submit your comments by the comment period deadline identified.

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 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 sulfur oxides (SO_X) and NAAQS have been established for sulfur dioxide (SO₂), an indicator for SO_X. Presently, EPA is reviewing the air quality criteria for SO_X and the NAAQS for SO₂. As part of its review of the NAAQS, EPA has prepared an assessment of exposures and characterization of health risks associated with ambient SO₂. Planned approaches to assessing exposures and characterizing risks were described in the document, Sulfur Dioxide Health Assessment Plan: Scope and Methods for Exposure and Risk Assessment. This planning 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 and 6, 2007. Comments received from that consultation were considered in developing the “Risk and Exposure Assessment to Support the Review of the SO₂ Primary National Ambient Air Quality Standards: First Draft,” which was released in July 2008.

The second draft of this document was released in March 2009 and conveys the approach taken to assess exposures to ambient SO₂ and to characterize associated health risks, as well as to present the results of those assessments. In addition, this document also contains a staff policy assessment that considers the evidence presented in the final Integrated Science Assessment and the exposure and risk characterization results presented in this second draft document, as they relate to the adequacy of the current SO₂ NAAQS and any potential alternative primary SO₂ standards. This draft document is available online at: http://www.epa.gov/​ttn/​naaqs/​standards/​so2/​s_​so2_​cr_​rea.html.

Dated: May 14, 2009.

Jenny Noonan Edwards,

Acting Director, Office of Air Quality Planning and Standards.