SUPPLEMENTARY INFORMATION:

I. Public Participation

Written Comments

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2023-0317, at https://www.regulations.gov (our preferred method), or the other methods identified above 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 to EPA's docket at https://www.regulations.gov any information you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), or other information for which disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission ( i.e., on the web, cloud, or other file sharing system). Please visit https://www.epa.gov/​dockets/​commenting-epa-dockets for additional submission methods; the full EPA public comment policy; information about CBI, PBI, or multimedia submissions; and general guidance on making effective comments.

II. Information About the Draft Document

Two sections of the Clean Air Act (CAA) 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 CAA section 109, the EPA is to establish primary (health-based) and secondary (welfare-based) NAAQS for each pollutant for which the EPA has issued air quality criteria. CAA section 109(d)(1) 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 CAA 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).^[1]

Presently the EPA is reviewing the health-based air quality criteria and primary NAAQS for oxides of nitrogen. The call for information for this review was issued in 2022.^[2] The EPA's overall plan for this review is presented in Volume 2 of the Integrated Review Plan for the NAAQS for Primary Oxides of Nitrogen (IRP).^[3] As described in Volume 2 of the IRP, and following consultation with the CASAC and consideration of public comments, the EPA has prepared an external review draft of the ISA to support the review of the primary nitrogen dioxide (NO₂) NAAQS. NO₂ is the oxide of nitrogen most commonly evaluated in health effects studies, and it is the indicator species for the primary NAAQS.

The ISA, when finalized, together with additional technical and policy assessments, will provide the scientific foundation for the EPA's decisions on the adequacy of the current primary NO₂ NAAQS and, if appropriate, on potential alternative standards. The draft ISA will be available on or about July 15, 2026, on the EPA's website at https://www.epa.gov/​naaqs/​nitrogen-dioxide-no2-primary-air-quality-standards, accessible under “Integrated Science Assessments” for the current primary NO₂ NAAQS review. Comments on the draft ISA should be submitted to the docket, as described above, by September 15, 2026. The EPA will consider comments submitted in response to this notice when revising the draft ISA.

The EPA is also soliciting advice and recommendations from the CASAC through a review of the draft ISA 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 preparation of the final ISA.

The draft ISA does not represent, and should not be construed to represent, any final EPA policy, viewpoint, or determination.

91 FR 44841