This document discusses various ways to reduce air pollution emissions, including establishing emissions standards, implementing state permitting programs, and encouraging voluntary reduction programs. It provides data on criteria pollutants and hazardous air pollutants regulated in the US. While emissions of some pollutants have decreased in recent decades, air toxics risks remain, and greenhouse gas levels continue increasing. The document suggests steps like improving vehicle technologies, expanding renewable energy and energy efficiency, and implementing smart growth development as ways to further curb emissions going forward.