Integrated Science Assessment (ISA) for Ozone and Related Photochemical Oxidants

The Integrated Science Assessment for Ozone and Related Photochemical Oxidants is a concise synthesis and evaluation of the most policy-relevant science, and has been prepared as part of the review of the primary (health-based) and secondary (welfare-based) National Ambient Air Quality Standards (NAAQS) for Ozone and Related Photochemical Oxidants under the Clean Air Act. Welfare effects are non-health effects which, according to the Clean Air Act include, but are not limited to, effects on soils, water, crops, vegetation, animals, wildlife and climate. The Ozone ISA, in conjunction with additional technical and policy assessments, provides the policy relevant scientific information necessary to conduct a review of the current primary and secondary air quality standards for Ozone sufficiently protects public health and welfare. 
EPA has established NAAQS for six criteria pollutants. Presently the EPA is reviewing the air quality criteria and NAAQS for photochemical oxidants and ozone; ozone is the current indicator for this NAAQS. 

Periodically, EPA reviews the scientific basis for these standards by preparing an Integrated Science Assessment (ISA). The ISA, in conjunction with additional technical and policy assessments, provides the policy relevant scientific information necessary to conduct a review of the current NAAQS and the appropriateness of possible alternative standards. These reviews play a significant role in EPA’s commitment to ensuring a clean and healthy environment for the public. 

EPA scientists are evaluating the latest scientific information to better understand the relationship between exposure to ozone and health and welfare effects, who may be at increased risk to these effects, how particles form in the atmosphere, and what the contributions are from various sources in different regions of the country. 

The Clean Air Act requires EPA to periodically review the science for six major air pollutants, including ozone. EPA's Center for Public Health and Environmental Assessment (formerly National Center for Environmental Assessment) develops Integrated Science Assessments (ISAs) that summarize the science related to the health and welfare effects of these pollutants. ISAs provide a comprehensive review of the policy-relevant scientific literature published since the last National Ambient Air Quality (NAAQS) review and in conjunction with other technical assessments, provide the policy-relevant scientific information necessary to conduct a review of the adequacy of the current NAAQS. This ISA represents EPA’s latest evaluation of the scientific literature on the potential health and welfare effects associated with ozone and updates the 2020 Integrated Science Assessment for Ozone and Related Photochemical Oxidants Final Report.