What improvements have been made in the 2002 NATA?
The EPA made several methodological changes to the 2002 NATA. Some of these were carried over from the 1999 NATA and applied again in 2002. EPA is continually refining or updating the assessment methods, but it is important to remember that these assessments are screening-level assessments. Their intent is to identify hazardous air pollutants resulting in high exposures or census tracts where population exposures may be of concern. These areas would then require more refined assessments, e.g., monitoring or site-specific risk assessments to develop a more through understanding of these “hot-spot” exposures. The list below summarizes the changes made.
