Integrated Review Plan for the National Ambient Air Quality Standards for Ozone and Related Photochemical Oxidants: Volume 2: Planning for the Review and the Integrated Science Assessment

This document is the second of three volumes that will comprise the IRP for the ozone NAAQS review. This Volume (2) of the integrated review plan (IRP) contains the current plans for the general approach for the review, as well as key planning considerations for the development of the integrated science assessment (ISA). The NAAQS review process provides an integrative assessment of relevant scientific information and will focus on key aspects of the NAAQS, including the basic elements of the standards: the indicator, averaging time, form, and level. These elements, which together serve to define each ambient air quality standard, are considered collectively in evaluating the protection to public health afforded by the standards.

Impact/Purpose

The U.S. Environmental Protection Agency (EPA) is conducting a review of the air quality criteria and the national ambient air quality standards (NAAQS) for ozone (O3) and related photochemical oxidants. This document is the second of three volumes that will comprise the integrated review plan (IRP) for the O3 NAAQS review. Volume 2 of the IRP contains the current plans for the general approach for the review, as well as key planning considerations for the development of the integrated science assessment (ISA). The NAAQS review process provides an integrative assessment of relevant scientific information and will focus on key aspects of the NAAQS, including the basic elements of the standards: the indicator, averaging time, form, and level. These elements, which together serve to define each ambient air quality standard, are considered collectively in evaluating the protection to public health and welfare afforded by the standards. Volume 1 of the IRP includes introductory and background information on the legislative requirements for reviews of the NAAQS, an overview of the review process, background information on prior reviews of the health and welfare-based air quality criteria and standards for ozone and related photochemical oxidants, a summary of key aspects of the basis for the existing O3 NAAQS, and a summary of the status and anticipated milestones for the current review. Volume 1 also includes an appendix that provides an overview of the key aspects of existing ambient air monitoring requirements for ozone. Volume 2 of the IRP (this document) presents the general approach for this review, the policy-relevant questions guiding the review, and the plans for the development of the ISA. Specifically, Chapter 2 of Volume 2 outlines the general approach of the NAAQS review and details a set of policy-relevant questions intended to focus this review on the critical scientific and policy issues. Chapter 3 of Volume 2 presents plans for the ISA, including the document organization, scope, and specific questions for consideration given the overarching policy-relevant questions for the review. Together, Volumes 1 and 2 provide the current information regarding this review of the O3 NAAQS. Volume 3 of the IRP, the planning document for quantitative analyses to be considered in the policy assessment (PA), will be developed with consideration of the availability of new evidence as identified in the draft ISA. Accordingly, public release of Volume 3 will generally coincide with that of the draft ISA, and it will be the subject of a consultation with the CASAC at that time.

Citation

Meng, Q., J. Herrick, P. Duffney, K. Novak, A. Martinez, AND C. Alvarez-Partin. Integrated Review Plan for the National Ambient Air Quality Standards for Ozone and Related Photochemical Oxidants: Volume 2: Planning for the Review and the Integrated Science Assessment. U.S. Environmental Protection Agency, Washington, DC, EPA/452/R-24/001b, 2024.

• https://www.epa.gov/naaqs/ozone-o3-standards-planning-documents-current-review