content_image/577797.jpg
<img src='content_image/577797.jpg'>

Source: EPA, Six Common Air Pollutants , 2013, http://www.epa.gov/airquality/urbanair/. 

## 3.2.2. Hazardous Air Pollutants 

Hazardous air pollutants (HAPs) are pollutants for which there are no NAAQS, but are regulated under the federal CAA because of their potentially adverse effects on human health and the environment. Also known as “air toxics”, these pollutants are comprised of a wide array 

