CC-12-015: Final Action on Secondary National Ambient Air Quality Standards for Oxides of Sulfur and Nitrogen

In the April 3, 2012 Federal Register, EPA published a final action that retains the current secondary National Ambient Air Quality Standards (NAAQS) for sulfur dioxide (SO2) and nitrogen dioxide (NO2). Although EPA had proposed a new 1-hour secondary SO2 standard, and a new 1-hour secondary NO2 standard, EPA decided these standards could not be justified on the basis of adverse ecological effects.