Previous research has established an association between air pollution and adult mortality. However, studies utilizing short-term fluctuations in pollution may detect mortality changes among the already ill or dying, while prospective cohort studies, which utilize geographic differences in long-run pollution levels, may suffer from severe omitted variables bias. This study utilizes the long-run reduction in total suspended particulates (TSPs) pollution induced by the Clean Air Act of 1970, which mandated aggressive regulation of local polluters in heavily polluted counties. We find that regulatory status is associated with large reductions in TSPs pollution but has little association with reductions in either adult or elderly mortality. These findings are interpreted with caution due to several caveats.