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Reviewing National Ambient Air Quality Standards (NAAQS): Scientific and Technical Information

The Clean Air Act requires EPA to review the standards – and the science behind them – periodically to determine whether changes are warranted. Learn more about EPA's NAAQS review process.

Reviewing National Ambient Air Quality Standards (NAAQS): Scientific and Technical Information

The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants that are common in outdoor air, considered harmful to public health and the environment, and that come from numerous and diverse sources.  

Carbon Monoxide (CO)

Particulate Matter (PM)