Both the full draft 1996 national-scale assessment and several
of the individual components of the assessment have been subjected
to the scrutiny of leading scientists throughout the country in
a process called "scientific peer review." This ensures that EPA
uses the best available scientific methods and information. The
following describes the various scientific peer review activities
which are associated with this assessment:
EPA's Science Advisory Board (SAB) reviewed the draft 1996 national-scale assessment during 2001. The review was generally very supportive of the assessment purpose, methods, and presentation -- the committee considers this an important step toward a better understanding of air toxics. This website reflects all of the SABís comments for revising or correcting the 1996 national-scale assessment. In addition, many of the SAB comments related to possible improvements for future assessments (additional national-scale assessments are being planned for the base year 1999 and for every three years thereafter) or raised technical issues which would merit further investigation. EPA will be following up on all of the issues raised by SAB and plans to publish a series of technical reports addressing the results of these investigations. These reports, which will provide the basis for improvements in future assessments, will be made available through links to this website. More information about the SAB's review is available through this link.
Scientists outside the EPA peer reviewed methods for measuring and estimating emission rates which are reported in the National Toxics Inventory (NTI).
EPA's Science Advisory Board peer-reviewed the ASPEN dispersion model used in the assessment in the context of its use in the Cumulative Exposure Project (CEP). The Science Advisory Board's issued their report in 1996. It can be found at
The HAPEM exposure model used in the assessment underwent a peer review by EPA scientists and an external peer review in the summer of 2000. While the peer review identified several limitations inherent in the current methodology, it is still acknowledged as an appropriate tool to help better understand the relation of human exposures to ambient concentration levels. For more information about this peer review.
The overall plan for the national-scale assessment underwent a peer review by EPA scientists and an external peer review by a six member panel of scientists.