Sulfur dioxide reduction at coal-fired power plants in North Carolina and associations with preterm birth among surrounding residents
Background: 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. Methods: We used US EPA Air Markets Program Data to track SO2 emissions and 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 postintervention, with a comparison of those living 10–<15 miles from CFPPs. Results: 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. For residents within 4–<10 miles from a CFPP, we estimated that the absolute prevalence of PTB decreased by −1.5% [95% confidence interval (CI): −2.6, −0.4] associated with scrubber installation and −0.5% (95% CI: −1.6, 0.6) associated with the retirement of coal units at CFPPs. Our findings were imprecise and generally null-to-positive among those living within 0–<4 miles regardless of the intervention type. Conclusions: Results suggest a reduction of PTB among residents 4–<10 miles of the CFPPs that installed scrubbers.