Sulfur dioxide reduction at coal-fired power plants in North Carolina and associations with preterm birth among surrounding residents
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Coal-fired power plants (CFPP) are major contributors of air pollution, including the majority of anthropogenic sulfur dioxide (SO2) emissions, which have been associated with preterm birth (PTB). To address a 2002 North Carolina (NC) policy, 14 of the largest NC CFPPs either installed desulfurization equipment (scrubbers) or retired coal units, resulting in substantial reductions of SO2 air emissions. We investigated whether SO2 air emission reduction strategies at CFPPs in NC were associated with changes in prevalence of PTB in nearby communities. We used US EPA Air Markets Program Data to determine the implementation dates of intervention at CFPPs and geocoded 2003-2015 NC singleton live births. We conducted a difference-in-difference analysis to estimate change in PTB associated with change in SO2 reduction strategies for populations living 0-<4 and 4-<10 miles from CFPPs pre- and post-intervention, with a comparison of those living 10-<15 miles from CFPPs. Reported average monthly SO2 air emissions from the CFPP-scrubber group (N=7) in the pre- and post-intervention periods were 4,933 and 342 tons, respectively. The CFPP-retired group (N=7) emitted a monthly average of 909 tons of SO2 pre-intervention versus <1 ton post-intervention. With the spatial-temporal exposure restrictions applied, 42,231 and 41,218 births were within 15 miles of CFPP-scrubbers and CFPP-retired groups, respectively. The estimated absolute prevalence of PTB decreased by 1.5% (95% CI: -2.6, -0.4) within 4-<10 miles from a CFPP after installation of scrubbers. When stratified by race/ethnicity, the absolute prevalence of PTB decreased for non-Hispanic (nH) Asian and nH white mothers by 8.2% (-14.1, -2.4) and 2.0% (-3.4, -0.6), respectively, with no change for nH Black [-0.4% (-3.2, 2.3)] and Hispanic [-0.0% (-2.6, 2.6)] mothers. Findings were imprecise and generally null among mothers living within 0-<4 miles regardless of the intervention type. This abstract does not represent EPA policy.