Reduced exposure to airborne particulate matter (PM2.5) has been the most significant source of health benefits from U.S. environmental regulation. These benefits are typically evaluated using integrated assessment models that ignore the potential for interactions between overlapping pollution regulations. In localities where threshold-based air quality standards bind, reductions in regional emissions could induce local regulators to permit offsetting increases in local emissions. We study the empirical relationship between regional emissions and local PM2.5 levels before and after stringent EPA regulations targeting power plants took effect. To isolate the effects of power plant emissions reductions, we combine high-resolution pollution transport modeling with an econometric model of local air pollution exposure. Consistent with the earlier literature, we find that reductions in power plant emissions have delivered significant improvements in local air quality. We also find that these effects are attenuated in localities that are constrained by air quality standards. This result is consistent with regulators relaxing local abatement efforts in response to a decline in regional emissions. Work-in-progress explores the health and equity implications of this local trade-off.