US EPA

EPA is preparing an Integrated Science Assessment (ISA) as part of the review of the air quality criteria and the primary (health-based) and secondary (welfare-based) National Ambient Air Quality Standards (NAAQS) for Ozone (O3) and related photochemical oxidants. The ISA will be developed by the Center for Public Health and Environmental Assessment (CPHEA) within EPA's Office of Research and Development (ORD). When final, the ISA is intended to update the previous Integrated Science Assessment for Ozone and Related Photochemical Oxidants (EPA/600/R–20/012, 2020), published on April 20, 2020. Interested parties are invited to assist EPA in developing and refining the scientific information base for the review of the O3 NAAQS by submitting research studies and data that have been published or accepted for publication since January 1, 2018.

EPA has established NAAQS for six criteria pollutants including ozone and related photochemical oxidants. Periodically, EPA reviews the scientific basis for these standards by preparing an ISA. In conjunction with additional technical and policy assessments conducted by EPA’s Office of Air Quality Planning and Standards (OAQPS), the ISA provides the scientific and technical basis for EPA decisions on the adequacy of the current NAAQS and the appropriateness of possible alternative standards.

Early steps in this process include announcing the beginning of this periodic NAAQS review and the development of the ISA, and EPA requesting that the public submit scientific literature that they want to bring to the attention of the Agency for consideration as it begins this review process. The Clean Air Scientific Advisory Committee (CASAC), whose review and advisory functions are mandated by section 109(d)(2) of the Clean Air Act, is charged (among other things) with independent scientific review of the Agency’s air quality criteria. In conjunction with the CASAC review, the public will have an opportunity to review and comment on the draft ISA as announced in the Federal Register. The ISA will build on the scientific assessment from the last review, focusing on assessing the information newly available since that considered in the 2020 ISA. With regard to development of the ISA, the public is encouraged to assist in identifying relevant scientific information for the review by submitting research studies that were not part of the prior review, and that have been published or accepted for publication in a peer-reviewed journal. The Agency is interested in obtaining newly available information, particularly concerning toxicological studies of effects of controlled exposure to O₃ in laboratory animals, humans, and in vitro systems; epidemiologic (observational) studies of health effects associated with ambient O3 exposures in human populations; studies examining populations and life stages that may be at increased risk of O₃-related health effects. For studies examining effects on welfare or the environment, studies that address or provide new information on terrestrial biota are of particular interest, including effects of O₃ on vegetation; communities and populations of plants and associated biota, as well as exposure-response relationships between O₃ in ambient air and specific welfare effects. The EPA also seeks recent information in other areas of O₃ research such as atmospheric chemistry and physics, sources and emissions, analytical methodology, transport and transformation in the environment, and ambient concentrations.

The Agency also seeks information regarding the design and scope of the review of the air quality criteria to ensure that it addresses key policy-relevant issues and considers the new science that is relevant to informing our understanding of these issues. The Agency seeks new scientific information that may address key uncertainties identified in the last O₃ NAAQS review, which are provided in section 3.6 of the 2020 Policy Assessment (EPA–452/R–20–001, May 2020). The Agency also seeks new scientific information or data that may address scientific and technical issues raised in two more recent letters from CASAC: one dated November 22, 2022 (EPA–CASAC–23–001) and the other dated June 9, 2023 (EPA–CASAC–23–002). Other opportunities for submission of new peer-reviewed, published (or in-press) papers will be possible as part of public comment on the draft ISA that will be reviewed by the CASAC.

To ensure this final statutory requirement is fully met, elsewhere in the August 25, 2023 Federal Register, EPA is issuing a call for information that would facilitate the committee's consideration of these issues.