US EPA

In February 2006, EPA released the final document, Air Quality Criteria for Ozone and Other Photochemical Oxidants. Tropospheric or surface-level ozone (O3) is one of six major air pollutants regulated by National Ambient Air Quality Standards (NAAQS) under the U.S. Clean Air Act. As mandated by the Clean Air Act, the U.S. Environmental Protection Agency (EPA) must periodically review the scientific bases (or criteria) for the various NAAQS by assessing newly available scientific information on a given criteria air pollutant. This document, Air Quality Criteria for Ozone and Other Photochemical Oxidants, is an updated revision of the 1996 Ozone Air Quality Criteria Document (O3 AQCD) that provided scientific bases for the current O3 NAAQS set in 1997.

The Clean Air Act mandates periodic review of the National Ambient Air Quality Standards (NAAQS) for six common air pollutants, also referred to as criteria pollutants, including ozone. Under the review process, EPA's Office of Research and Development develops a criteria document - a compilation and evaluation by U.S. EPA scientific staff and other expert authors of the latest scientific knowledge relevant to assessing the health and welfare effects of the air pollutant. In this case, the Ozone Criteria Document presents the latest available pertinent information on atmospheric science, air quality, exposure, dosimetry, health effects, and environmental effects of ozone and other related photochemical oxidants.

Development of the Ozone Criteria Document has included extensive review by the Clean Air Scientific Advisory Committee (CASAC) and the public. The document is divided into three volumes:

• Volume I (Executive Summary and Chapters 1 through 11);
• Volume II (annexes to Chapters 2 through 7), and
• Volume III (annex to Chapter 9).

The Clean Air Act mandates periodic review of the National Ambient Air Quality Standards (NAAQS) for six common air pollutants, also referred to as criteria pollutants, including ozone.

As a follow-up, EPA's Office of Air Quality Planning and Standards (OAQPS) prepared a staff paper that bridges the gap between scientific assessments in the criteria document and judgments required of the EPA Administrator in evaluating whether to retain or revise the Ozone NAAQS.

U.S. EPA. Air Quality Criteria For Ozone and Related Photochemical Oxidants (Final Report, 2006). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-05/004aF-cF, 2006.