The legacy of the U.S. Clean Air Act at a crossroads

Chronic and acute exposure to elevated concentrations of ambient fine particulate matter represents a significant health risk. Here, we evaluate the avoided air pollution due to the U.S. Clean Air Act and the potential of the 2016 Paris Agreement to improve air quality in the contiguous U.S. The current weakening of federal agencies in the U.S. will degrade environmental quality, induce sickness and death, and incur costs.