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National Ambient Air Quality Standards (NAAQS)

Ozone (O3) Standards


October 1, 2015 - EPA is strengthening the National Ambient Air Quality Standards (NAAQS) for ground-level ozone, based on extensive scientific evidence about ozone's effects.

The Clean Air Act requires EPA to set national ambient air quality standards (NAAQS) for ozone and five other pollutants considered harmful to public health and the environment (the other pollutants are particulate matter, nitrogen oxides, carbon monoxide, sulfur dioxide and lead). The law also requires EPA to periodically review the standards to ensure that they provide adequate health and environmental protection, and to update those standards as necessary. Learn more about the NAAQS review process.

Contact: Susan Lyon Stone

Documents from Current Review

Basic Information on Ground-level Ozone

Documents from Review Completed in 2008 (including documents related to the reconsideration)

Documents from Review Completed in 1997

Documents from Previous Reviews

Table of Current NAAQS

Table of Historical Ozone NAAQS

Air Quality Index


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