US EPA

A reconsideration of the national ambient air quality standards (NAAQS) for O₃ is currently underway. The last Air Quality Criteria Document for Ozone and Related Photochemical Oxidants (O₃ AQCD) was released in final form in February 2006. That NAAQS review for O₃ was completed with a final rule signed in March 2008. On September 16, 2009, the EPA Administrator announced a decision to reconsider the primary and secondary NAAQS for O₃ based on the record from the last review. The EPA has conducted a provisional assessment of studies investigating the health and ecological effects of O₃ published in recent years that were not included in the O₃ AQCD. The O₃ AQCD included a rigorous and thorough review of pertinent literature accepted for publication through December 2004 and a limited number of papers accepted for publication in 2005 and 2006. In the provisional assessment, EPA examined recent studies in light of the literature evaluated in the O₃ AQCD. The intent of this assessment was to determine if recent studies materially change the conclusions of the O₃ AQCD.

The intent of this provisional assessment is to determine if studies published since the 2006 O3 AQCD materially change the conclusions of that document.

U.S. EPA. Provisional assessment of recent studies on health and ecological effects of ozone exposure. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/101, 2009.