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Section 112 of the Clean Air Act (the Act) governs the regulation of hazardous air pollutants. From 1970 to 1990, the statute required the United States Environmental Protection Agency (EPA) to regulate hazardous air pollutants on a pollutant-by-pollutant basis. Environmental policy analysts generally acknowledge that this approach failed due to scientific uncertainties and unclear direction from Congress on how the EPA should balance the competing concerns of cost and safety. In an effort to improve the Act's effectiveness, Congress passed the 1990 Amendments (the Amendments) to the Act, which established a two-phased approach to regulation. First, subsection 112(d) requires the EPA to promulgate technology-based emission standards for categories and subcategories of industries that are major or area sources of 189 specified hazardous air pollutants. Because Congress was concerned that these controls would not eliminate all emissions posing unacceptable health risks to exposed populations, subsection 112(f) then requires the EPA to determine for each category or subcategory of industries whether more stringent emission standards should be promulgated to control residual risks.

Given the previously slow pace of regulation, Congress was probably right to emphasize speed and scope, rather than stringency and health, in requiring the EPA to promulgate national, uniform technology-based regulations for categories and subcategories of industries. The residual risk provisions in subsection 112 (f), however, provide only vague guidelines for the EPA to follow in establishing health-based standards after the technologybased approach is in place. In fact, the residual risk provisions adopt essentially the same approach to health-based regulation that failed in the pre-1990 version of the statute. Subsection 112(f) requires the EPA to examine the cancer risk of individual facilities in determining whether the agency must promulgate residual risk standards, but then requires the agency to issue such standards for a category or subcategory of industry rather than for the individual facilities.

This Article proposes establishing an "exceptions process" to exempt individual facilities from both the categorical technologybased standards in subsection 112(d) and the residual risk standards in subsection 112 (f). Under this approach, a firm could apply for a variance from either type of standard following a sitespecific risk assessment that demonstrates that (a) the costs of the standard are disproportionate to the benefits, and that (b) there is not an unacceptable risk to surrounding residents. At the same time, this approach would enable citizens to request a more stringent standard for an individual facility upon proof that the existing standards inadequately control the health risks presented by the facility.