THE CLEAN AIR ACT of 1970 (CAA) is broadly understood as a pivotal moment in the history of U.S. environmental policy, entailing a radical shift away from an earlier common law regime that was operated piecemeal by local and state governments. The CAA superceded these decentralized approaches with federal, uniform, and proactive law. But most importantly, it is thought to embody a shift in priorities away from an earlier deference to industrial concerns toward a new and uncompromising commitment to the protection of public health.
The act’s absolutist reputation rests primarily on the ambitiousness of the promise it encodes in a central provision mandating the promulgation of primary ambient air-quality standards.1 In setting these standards, the act requires the EPA to establish maximum permitted levels of regulated pollutants no higher than what the protection of public health against pollution-induced disease demands. These standards exemplify a broader category of regulatory interventions based on scientific assessment of hazards from pollution exposure, frequently termed “risk-based” or “healthbased” standards. In addition, the CAA employs a secondary regulatory framework that sets standards based on the feasibility of pollution mitigation, termed “technology standards.” Whereas technology standards are inherently based on feasibility and cost, these considerations may not be taken into account in setting risk standards.
Terms for technology standards include “Best Available Technology” (BAT), “Best Practicable Means” (BPM), “Maximum Achievable Control Technology” (MACT), and many others. All of these approaches employ the similar core logic of setting standards with reference to the pollution reduction capabilities of specific technological means. The standards can take the form of a requirement to install particular pollution-control devices or employ other mitigation measures (prescriptive standards). More commonly, however, these standards impose a percentage reduction in emission that is known to be achievable through technological measures of demonstrated feasibility (performance standards).2 In the latter case, sources are free to employ alternative means, as long as they afford pollution reduction at least equal to the level of effectiveness that can be achieved by the technology serving as the basis for the standard.
I argue that technology and risk standards represent the current incarnation of alternative responses to the regulatory dilemma posed by air pollution since the beginning of industrialization. By the mid-nineteenth