Improved asthma outcomes observed in the vicinity of coal power plant retirement, retrofit and conversion to natural gas

Abstract

Coal-fired power plants release substantial air pollution, which included over 60% of US sulfur dioxide emissions in 2014. Such air pollution may exacerbate asthma, but direct studies of the health impacts linked to power plant air pollution are rare. Here we take advantage of a natural experiment in Louisville, Kentucky, where one coal-fired power plant was retired and converted to natural gas, and three others installed SO₂ emission control systems between 2013 and 2016. Dispersion modelling indicated that exposure to SO₂ emissions from these power plants decreased after the energy transitions. We used several analysis strategies, which include difference-in-differences, first-difference and interrupted time-series modelling to show that the emissions control installations and plant retirements are associated with a reduced asthma disease burden related to hospitalizations and emergency room visits at the ZIP-code level, and to individual-level medication use as measured by digital medication sensors.