Skip to Content


Draft Risk and Exposure Assessment Report for Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur

Document Details

Information about this document as published in the Federal Register.

Enhanced Content

Relevant information about this document from provides additional context. This information is not part of the official Federal Register document.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Environmental Protection Agency (EPA).


Notice of draft report for public review and comment.


On or about June 5, 2009, the Office of Air Quality Planning and Standards (OAQPS) of EPA is making available for public review and comment a draft 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.” The purpose of this draft 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.


Comments on the above report must be received on or before July 17, 2009.


Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2007-1145, by one of the following methods:

  • Follow the on-line instructions for submitting comments.
  • E-mail: Comments may be sent by electronic mail (e-mail) to, Attention Docket ID No. EPA-HQ-OAR-2007-1145.
  • Fax: Fax your comments to 202-566-9744, Attention Docket ID No. EPA-HQ-OAR-2007-1145.
  • 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-2007-1145.
  • Hand Delivery or Courier: Deliver your comments to: EPA Docket Center, 1301 Constitution Ave., NW., Room 3334, Washington, DC. Such deliveries Start Printed Page 28699are 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-2007-1145. 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, 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 or e-mail. The 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, 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​epahome/​dockets.htm.

Docket: All documents in the docket are listed in the 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 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 202-566-9744.

Start Further Info


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

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 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.
End Further Info End Preamble Start Supplemental 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.

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 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 Start Printed Page 28700public 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 have been 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 is being released at this time.

The second draft risk and exposure assessment for the secondary NOX/SOX NAAQS review released at this time conveys the approach taken to assess ecological effects due to the deposition of ambient NOX and SOX, and present the results of these analyses. This draft document will be available online at:​ttn/​naaqs/​standards/​no2so2sec/​cr_​rea.html.

The EPA is soliciting advice and recommendations from the CASAC and public comments by means of a review of the draft document at an upcoming public meeting of the CASAC scheduled for July 22-23, 2009 in Research Triangle Park, NC. A separate Federal Register notice will provide additional details about this meeting and the process for participation. Following the CASAC meeting, EPA will consider comments received from the CASAC and the public in preparing a final risk and exposure assessment report.

Start Signature

Dated: June 4, 2009.

Jenny N. Edmonds,

Acting Director, Office of Air Quality Planning and Standards.

End Signature End Supplemental Information

[FR Doc. E9-14238 Filed 6-16-09; 8:45 am]