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Nitrogen Dioxide (NO2) and Sulfur Dioxide (SO2) Secondary Standards

The Clean Air Act requires EPA to set national air quality standards for six criteria pollutants (nitrogen oxides, sulfur oxides, particulate matter, ozone, carbon monoxide, and lead) based on primary (health-based) and secondary (welfare-based) considerations. The law also requires EPA to periodically review the scientific criteria upon which the standards are based  (learn more about this process).  While EPA generally reviews criteria and standards for each of the six criteria pollutants individually, for this review of the secondary standards for NO2 and SO2, EPA has decided to examine nitrogen oxide (NOx) and sulfur oxide (SOx) compounds together.  EPA recognizes that NOx, SOx are inextricably linked from both an atmospheric chemistry and environmental effects perspectives.

Contact:      Anne Rea
                    Rea.anne@epa.gov
                    919-541-0053

Documents from Current Review

Documents from NO2 Review Completed in 1996  

Documents from SO2 Review Completed in 1996

Plain Language Information About Pollutant

Summary of Current NAAQS Table

 

 

File Utilities

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