As part of EPA's National Air Toxics Assessment activities, EPA conducted a national-scale assessment of 33 air pollutants (a subset of 32 air toxics on the Clean Air Act's list of 188 air toxics plus diesel particulate matter (diesel PM)). The assessment includes four steps that look at the year 1996. Note: As of May 2002, the results posted for all four steps include revisions based on input from scientific peer review.
- Compiling a national emissions inventory of air toxics emissions from outdoor sources. Available here
- Estimating ambient concentrations of air toxics across the contiguous United States. Available here
- Estimating population exposures across the contiguous United States. Available here
- Characterizing potential public health risk due to inhalation of air toxics including both cancer and noncancer effects. Available here
The goal of the national-scale assessment is to identify those air toxics which are of greatest potential concern, in terms of contribution to population risk. The results will be used to set priorities for the collection of additional air toxics data (e.g., emissions data and ambient monitoring data). In February 2006, EPA released the results of its national-scale assessment of 1999 air toxics emissions .