Based on a nationwide representative county-level dataset from China, this article empirically examines the spillover effects of air pollution from neighboring coal-fired power plants on local mortality rates due to cardiovascular and respiratory diseases. We combine data on power plants' industrial output with information on wind direction and speed to proxy for air pollution, and find that air pollution from neighboring power plants indeed has significant negative effects on local public health. The resulting treatment costs are also enormous. Our findings shed light on the necessity of intergovernmental cooperation in environmental governance.