Review of the National Ambient Air Quality Standards for Oxides of Nitrogen

Under the Clean Air Act Amendments of 1977, EPA is required to periodically review and if appropriate revise the air quality criteria for the primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS). There are primary and secondary NAAQS for oxides of nitrogen providing protection of public health and welfare. This action will address EPA’s obligation to periodically review the primary NAAQS for oxides of nitrogen.