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Release of Integrated Review Plan for the Primary National Ambient Air Quality Standard for Sulfur Dioxide

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Environmental Protection Agency.


Notice of availability.


The Environmental Protection Agency (EPA) is announcing the availability of a final document titled Integrated Review Plan for the Primary National Ambient Air Quality Standard for Sulfur Dioxide (IRP). This document contains the plans for the review of the air quality criteria for health for sulfur oxides and the primary national ambient air quality standard (NAAQS) for sulfur dioxide (SO2). The primary SO2 NAAQS provide for the protection of public health from exposure to sulfur oxides in ambient air.


The IRP will be available on or about October 30, 2014.


This document will be available primarily via the Internet at the following Web site : http://Start Printed Page​ttn/​naaqs/​standards/​so2/​s_​so2_​2013_​pd.html.

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Dr. Michael J. Stewart, Office of Air Quality Planning and Standards (mail code C504-06), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; telephone number: 919-541-7524; fax number: 919-541-0237; email address:

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Two sections of the Clean Air Act (CAA) govern the establishment and revision of the NAAQS. Section 108 (42 U.S.C. 7408) directs the Administrator to identify and list certain air pollutants and then to issue air quality criteria for those pollutants. The Administrator is to list those air pollutants that in her “judgment, cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare;” “the presence of which in the ambient air results from numerous or diverse mobile or stationary sources;” and “for which . . . [the Administrator] plans to issue air quality criteria. . . .” Air quality criteria are intended 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 . . .” (42 U.S.C. 7408(b)). Under section 109 (42 U.S.C. 7409), the EPA establishes primary (health-based) and secondary (welfare-based) NAAQS for pollutants for which air quality criteria are issued. Section 109(d) 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, if appropriate, revise the NAAQS based on the revised criteria. Section 109(d)(2) requires that an independent scientific review committee “shall complete a review of the criteria . . . and the national primary and secondary ambient air quality standards . . . and shall recommend to the Administrator any new . . . standards and revisions of existing criteria and standards as may be appropriate. . . .” Since the early 1980's, this independent review function has been performed by the Clean Air Scientific Advisory Committee (CASAC).

Presently, the EPA is reviewing the primary NAAQS for SO2.[1] The final document, announced today, has been developed as part of the planning phase for the review. This phase began with a science policy workshop to identify issues and questions to frame the review.[2] Drawing from the workshop discussions, a draft IRP was prepared jointly by the EPA's National Center for Environmental Assessment, within the Office of Research and Development, and EPA's Office of Air Quality Planning and Standards, within the Office of Air and Radiation (79 FR 14035). The draft IRP was reviewed by CASAC at a teleconference on April 22, 2014 (79 FR 16325). Comments from the CASAC on the draft IRP were provided to us in a July 24, 2014, letter (Frey and Diez-Roux, 2014).[3] The final IRP includes consideration of CASAC and public comments received on the draft IRP. This document presents the current plan and specifies the schedule for the entire review, the process for conducting the review, and the key policy-relevant science issues that will guide the review.

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Dated: November 3, 2014.

Mary E. Henigin,

Acting Director, Office of Air Quality Planning and Standards.

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1.  The EPA's call for information for this review was issued on May 10, 2013 (78 FR 27387).

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2.  The EPA held a workshop entitled “Workshop to Discuss Policy Relevant Science to Inform EPA's Integrated Plan for Review of the National Ambient Air Quality Standards for Sulfur Oxides” on June 12-13, 2013 (78 FR 27387).

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3.  Letter from Dr. H. Christopher Frey and Dr. Ana Diez-Roux, Chairs, Clean Air Scientific Advisory Committee to the Honorable Gina McCarthy, Administrator, US EPA. CASAC Review of the EPA's Integrated Review Plan for the Primary National Ambient Air Quality Standard for Sulfur Dioxide (External Review Draft—March 2014). July 24, 2014. Available at:​sab/​sabproduct.nsf/​4620a620d0120f93852572410080d786/​CB76219103736A8185257D20006D033D/​$File/​EPA-CASAC-14-006+​unsigned.pdf.

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[FR Doc. 2014-26623 Filed 11-7-14; 8:45 am]