Can access to health care mitigate the effects of temperature on mortality?

Understanding the sources of heterogeneity in the health effects of environmental exposure is critical for optimal policy design. Differential access to health care is commonly cited as a potential source of such heterogeneity. We test this hypothesis in a causal framework by combining random year-to-year fluctuations in local temperatures with variation in access to primary care services resulting from the idiosyncratic roll-out of Community Health Centers (CHCs) across US counties in the 1960s and 1970s. We find that the improved access to primary care services provided by CHCs moderates the heat-mortality relationship by 14.2%, but we find little evidence that CHC access mitigates the harmful effects of cold. In a supplementary analysis we find evidence that acute care – in contrast to primary care – may be especially effective at mitigating the cold-mortality relationship. Our results suggest that differential access to health care does contribute to observed heterogeneity in environmental health damages, and that improving access to primary care may be a useful means of mitigating harm from a warming climate.