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Regulatory Development and Retrospective Review Tracker

Ozone and Fine Particulate Matter (PM2.5) Significant Impact Levels (SILs) for Prevention of Significant Deterioration (PSD) Program

a.k.a. Ozone and Fine Particulate Matter (PM2.5) Significant Impact Levels (SILs) for Prevention of Significant Deterioration (PSD) Program

RIN: 2060-AR28 (What's this?)

Docket No.: Not yet available (What's this?)

Current Phase: Pre-Proposal (What's this?)

This proposed action will establish Significant Impact Levels (SILs) for ozone and PM2.5 to facilitate implementation of the Prevention of Significant Deterioration (PSD) program in areas attaining the national ambient air quality standards (NAAQS) for Ozone or PM2.5.

The SILs for Ozone and PM2.5 would be used as compliance demonstration tools by permitting authorities to help determine whether the projected emissions from a proposed new major source or major modification will cause or contribute to a violation of the NAAQS. This proposed action is, in part, in response to the January 22, 2013, D.C. Circuit's decision that vacated the PM2.5 Significant Monitoring Concentration (SMC) and vacated and remanded two provisions in the EPA's PSD regulations containing SILs that were contained in the 2010 rule promulgating increments, SMCs, and SILs for PM2.5. Furthermore, in August 2011, the Texas Commission on Environmental Quality (TCEQ) filed a Petition for Reconsideration to the Administrator regarding several provisions contained in the 2010 PM2.5 final rule, claiming that EPA did not provide an opportunity for public comment prior to issuing the provisions as part of the final rule. In response to the TCEQ petition, EPA will reconsider the following provisions: 1) The revised definition of "baseline area" that includes a new significance level for PM2.5, which is used for determining whether a particular attainment or unclassifiable area should be included in the baseline area for the PM2.5 increments; and 2) The requirement that PM2.5 precursor emissions be included in the significant impact analysis. The EPA intends to address all of the above mentioned items with this rulemaking. This proposed action will the first to add SILs for ozone to the PSD regulations.

NPRM: Published in FR00/0000 (projected)

Potential Effects

Environmental Justice
This rulemaking involves a topic that is likely to be of particular interest to or have particular impact upon minority, low-income, tribal, and/or other vulnerable populations because:

  • This topic is likely to affect the availability of information to vulnerable populations.

Participate / Learn More Regulatory Review

Some of EPA's rulemakings undergo regulatory review (What's this?), as prescribed by Executive Order 12866 and coordinated by the Office of Management and Budget (OMB). The following list describes which of this rulemaking's stages have completed review and published in the Federal Register, if any, and provides links to the review documents where available. Consult the "Timeline" section of this Web page for the dates of each review.

  • NPRM - This stage of the rulemaking underwent review.
Citations & Authorities

Code of Federal Regulations (CFR) Citation
40 CFR 51.156

Legal Authority
42 U.S.C. 7470-7479


This site provides summaries of priority rulemakings and priority retrospective reviews of existing regulations. We update most of the site at the beginning of each month, though some data is updated more frequently if it is time sensitive. The information on this site is not intended to and does not commit EPA to specific conclusions or actions. For example, after further analysis, EPA may decide the effects of a rule would be different or it may decide to terminate a rulemaking.

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