Air pollution is a leading health risk factor and important contributor to regional climate change in China and other parts of Asia. China’s particulate matter (PM) air pollution dramatically exceeds health guidelines and is impacted by industrial emissions, motor vehicles, and household use of biomass and coal fuels. Black carbon (BC) from biomass and fossil fuel burning is a major climate-forcing component of PM. We found that BC exposure from biomass smoke is more strongly associated with blood pressure than total PM mass, and that coexposure to motor vehicle emissions may strengthen BC’s impact. Air pollution mitigation efforts focusing on reducing combustion pollution are likely to have major benefits for climate and human health.