Previous research has established that pollution-control legislation and regula­ tions favor struggling industries and slower-growing regions. The government’s sensitivity to politically awkward trade-offs between pollution control and jobs reveals itself in special deals stretching out the compliance schedules of individual industries, in regulations biased against new sources, and in congressional voting patterns on policies like PSD (prevention of significant deterioration) (Crandall [4]; Pashigian [25]).2 Given this history, it seems likely that the potential political costs of pollution control have also influenced regulators’ enforcement decisions.