SUPPLEMENTARY INFORMATION:

I. General Information

Written Comments

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2018-0279, at https://www.regulations.gov (our preferred method), or the other methods identified in the ADDRESSES section. Once submitted, comments cannot be edited or removed from the docket. The EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written submission. The written submission is considered the official submission and should include discussion of all points you wish to make. The EPA will generally not consider submissions or submission content located outside of the primary submission ( i.e., on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa.gov/​dockets/​commenting-epa-dockets.

II. Information About the Document

Two sections of the Clean Air Act (CAA or the Act) govern the establishment and revision of the NAAQS. Section 108 directs the Administrator to identify and list certain air pollutants and then issue “air quality criteria” for those 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 such pollutant in the ambient air . . .” (CAA section 108(a)(2)). Under section 109 of the Act, the EPA is then to establish primary (health-based) and secondary (welfare-based) NAAQS for each pollutant for which the EPA has issued air quality criteria. Section 109(d)(1) of the Act requires periodic review and, if appropriate, revision of existing air quality criteria. Revised air quality criteria are to reflect advances in scientific knowledge on the effects of the pollutant on public health and welfare. Under the same provision, the EPA is also to periodically review and, if appropriate, revise the NAAQS, based on the revised air quality criteria.

The Act additionally requires appointment of an independent scientific review committee that is to periodically review the existing air quality criteria and NAAQS and to recommend any new standards and revisions of existing criteria and standards as may be appropriate (CAA section 109(d)(2)(A)-(B)). Since the early 1980s, the requirement for an independent scientific review committee has been fulfilled by the Clean Air Scientific Advisory Committee (CASAC).

Presently the EPA is reviewing the air quality criteria and NAAQS for photochemical oxidants and O₃ .^[1] The EPA's overall plan for this review is presented in the Integrated Review Plan for the Ozone NAAQS (IRP).^[2] As described in the IRP, the EPA is preparing an Integrated Science Assessment for (ISA), a draft of which was released in September 2019 for public comment and review by the CASAC (84 FR 50836).^[3] The PA, when final, serves to “bridge the gap” between the scientific and technical information in the final ISA and any air quality, exposure and risk analyses available in the review, and the judgments required of the Administrator in determining whether to retain or revise the existing ozone NAAQS. The draft PA builds upon information presented in the draft ISA and the draft exposure and risk analyses (presented in an appendix to the draft PA). The draft PA document will be available on or about October 31, 2019, on the EPA's website at https://www.epa.gov/​naaqs/​ozone-o3-air-quality-standards. The EPA is soliciting advice and recommendations from the CASAC by means of a review of this draft document at an upcoming public meeting of the CASAC. Information about this public meeting, including the dates and location, will be published as a separate notice in the Federal Register . Following the CASAC meeting, the EPA will consider comments received from the CASAC and the public in preparing revisions to these documents.

The draft document briefly described above does not represent and should not be construed to represent any final EPA policy, viewpoint, or determination. The EPA will consider any public comments submitted in response to this notice when revising the document.