The Clean Air Act's National Ambient Air Quality Standards (NAAQS) set limits on ambient air concentrations of hazardous pollutants. Since its creation, NAAQS guidelines have evolved to curb ambient concentrations of Particulate Matter less than 2.5 ug in diameter (PM2.5), which have been linked...

In the US, much of the authority to administer the Clean Air Act (CAA) is delegated to indi-vidual states. States are responsible primarily for the administration of the National Ambient Air Quality Standards (NAAQS), which impose technological and other requirements on stationary emission...