OverviewThe National-Scale Air Toxics Assessment, which is based
on 1996 emissions data, produced results that are useful in
understanding the quality of air and its possible effect on
human health nationwide. The assessment looked at 33 air
pollutants (a subset of 32 air toxics from the Clean Air Act's
list of 188 air toxics plus diesel particulate matter).
Specifically, it consisted of 4 steps that produced nationwide
estimates of: (1) the release of these pollutants into the air
from various sources; (2) the concentration of these compounds
in the air; (3) the exposure of populations to this air; and (4)
the risk of both cancer and noncancer health effects resulting
from this exposure. - More on the 4 Steps of the Assessment -
More Information on the 33 pollutants - EPA's Use of the Results
Download a NATA Technical Fact Sheet in pdf format.