Residual Risk

In March 1999, EPA released a final report called "Residual Risk Report to Congress." This report described the proposed strategy that the agency would use to assess health and environmental risks from air toxics remaining after implementation of technology or performance-based air toxics regulations (MACT) required under the Clean Air Act. This remaining risk is referred to as "residual risk." The Clean Air Act requires EPA to assess residual risks, and if necessary, promulgate additional regulations for source categories. Some of the first standards under the Residual Risk program would be, if necessary, Gasoline Distribution, HON, and Petroleum Refineries.

EPA is using a two-tier risk approach to determine the extent of the residual risk for Gasoline Distribution, HON, and Petroleum Refineries. The first tier is a screening level assessment. This followed, if necessary, by a second tier consisting of a more detailed or refined assessment. The purpose of the screening risk assessment is to eliminate low-risk source categories, sources within categories, or certain hazardous air pollutants (HAPs) from further analysis. The screening assessment is conservative in nature, relying on readily available data and defaults. On the other hand, the refined assessment is more realistic and therefore more resource intensive. The refined assessment provides the basis for setting standards.

EPA is in the process of conducting preliminary analyses for the Gasoline Distribution MACT, Refinery MACT I and co-located facilities, and the HON..

Link to EPA air toxics site http://www.epa.gov/air/toxicair/index.html

Link to 1999 EPA report to Congress http://www.epa.gov/ttncaaa1/t3/reports/risk_rep.pdf

Additional Information on this issue for NPRA members can be found at
http://www.npra.org/members/environmental/news.cfm Under sub-section Residual Risk