"This memorandum responds to your request regarding facilities submitting risk management plans (RMPs) to the U.S. Environmental Protection Agency (EPA). You requested an analysis of RMP facilities within the United States by potentially affected population. You also requested an analysis of facilities that were required by regulation to resubmit their information to the EPA but had not done so. Under the Clean Air Act, Section 112(r), the EPA established a program requiring facilities possessing greater than certain threshold quantities of 140 chemicals to provide risk management plans to the EPA. As part of this reporting requirement, facilities are required to determine the worst-case scenario release from a single chemical process, using EPA criteria and guidelines. Facilities are also required to estimate the population potentially at risk from this worst-case scenario release by calculating the population that resides within a circle surrounding the facility, with the radius of the circle determined by the distance the worst-case scenario release might travel."
CRS Memorandum, March 4, 2008