Skip to Content

We invite you to try out our new beta eCFR site at We’ve made big changes to make the eCFR easier to use. Be sure to leave feedback using the 'Help' button on the bottom right of each page!


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.

Document Statistics
Document page views are updated periodically throughout the day and are cumulative counts for this document. Counts are subject to sampling, reprocessing and revision (up or down) throughout the day.
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).


Extension of comment period.


The Office of Air Quality Planning and Standards (OAQPS) of EPA recently made available a draft report, Policy Assessment for the Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Second External Review Draft (75 FR 57463, September 21, 2010). The EPA released this preliminary draft document to seek early consultation with the Clean Air Scientific Advisory Committee (CASAC) and to solicit public comment on the overall structure, framing of key issues and conclusions regarding options for key elements of the standards. Four supplementary materials were released at a later date (75 FR 61486, October 5, 2010). The supplementary materials were: an errata sheet for Chapter 5; an addendum for Chapter 5; an additional Table 7-1 (summary of key uncertainties); and an additional table for Chapter 9 (summary of options for elements of the nitrogen oxides (NOX) and sulfur oxides (SOX) standard). Comments were originally scheduled to be submitted on or before November 12, 2010. A request for an extension to the comment period has been received. The EPA is granting this extension to allow stakeholders and the public with adequate time to conduct appropriate analysis and meaningful comments. Therefore, the comment period is being moved from November 12, 2010, to November 26, 2010.


Comments should be submitted on or before November 26, 2010.


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 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-2007-1145. 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 http://, 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.

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 Start Printed Page 70259Constitution 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. Bryan Hubbell, Office of Air Quality Planning and Standards (Mail code C504-02), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; e-mail:; telephone: 919-541-0621; fax: 919-541-0804.

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.
  • Make sure to submit your comments by the comment period deadline identified.

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 NOX and 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 NOX and SOX. 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 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 this review of the current secondary (welfare-based) NAAQS for NOX and SOX, EPA's OAQPS staff prepared a second draft Policy Assessment. The objective of this assessment is to evaluate the policy implications of the key scientific information contained in the document Integrated Science Assessment for Oxides of Nitrogen and Sulfur-Ecological Criteria (​ncea/​cfm/​recordisplay.cfm?​deid=​201485), prepared by EPA's National Center for Environmental Assessment (NCEA) and the results from the analyses contained in the Risk and Exposure Assessment for Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur (​ttn/​naaqs/​standards/​no2so2sec/​cr_​rea.html). The second draft Policy Assessment plus the supplementary materials are available online at:​ttn/​naaqs/​standards/​no2so2sec/​index.html. This second draft Policy Assessment was reviewed by the CASAC during a public meeting which was held on October 6 and 7, 2010.

Start Signature

Dated: November 8, 2010.

Jennifer Noonan Edmonds,

Acting Director, Office of Air Quality Planning and Standards.

End Signature End Further Info End Preamble

[FR Doc. 2010-28969 Filed 11-16-10; 8:45 am]