Installment of desulfurization equipment at coal-fired power plants in North Carolina and associations with preterm birth among surrounding residents

Abstract

Background: Coal-fired power plants (CFPPs) are major contributors of air pollution globally. In 2002, North Carolina (NC) adopted regulation that required CFPPs to substantially reduce their sulfur dioxide (SO2) emissions by 2013. CFPPs complying with this regulation have resulted in measurable decreases of ambient SO2 across NC. Air pollution research suggests an association between ambient SO2 and preterm birth (PTB, gestational age < 37 completed weeks). PTB is an important risk factor for neonatal mortality and associated with high healthcare costs. This study aims to evaluate the impact of SO2 emissions reduction strategies at CFPPs on preterm birth in North Carolina.Methods: The US Environmental Protection Agency’s Air Markets Program data were used to determine when the SO2 emissions reduction strategies were implemented at NC’s largest CFPPs (capacity > 150 megawatts). The study population was derived from geocoded NC resident singleton live birth data from 2003-2015 obtained from the NC State Center for Health Statistics. A difference-in-difference analysis using a linear mixed model with random intercepts for the CFPPs will be employed to compare the risk of PTB for mothers living 0-5 miles and 5-10 miles from the CFPPs before and after the intervention, with a control of mothers living 10-15 miles from the CFPPs.Results: During the study period, 7 CFPPs installed desulfurization equipment (i.e. SO2 scrubbers). The median concentration for reported monthly SO2 air emissions from the CFPPs in the pre-period and post-period were 4,421 tons and 281 tons, respectively. With the spatial and temporal exposure restrictions applied, there were 42,076 births within 15 miles of the CFPPs.Conclusions: This study comes at a time when the United States government is considering whether to move away from or reinvest in coal for electricity generation.