Impacts of Prenatal Exposure to Sulfure Dioxide on Infant Birth Weight: Evidence from a Pennsylvania Plant Located Upwind of New Jersey

This study examines the impact of prenatal exposure to sulfur dioxide on infant birth outcomes, specifically, the occurrence of very low birth weight (VLBW).  VLBW infants, weighing fewer than 1,500 grams at birth, not only impose substantial financial costs, but also tend to experience poor health, educational, and daily living outcomes through adulthood.

For our study, we integrate three data sources:  the EPA’s Air Quality System; the National Climatic Data Center; and the State Inpatient Databases of the Healthcare Cost and Utilization Project.  Our identification strategy exploits a unique setting in which sulfur dioxide emitted from a power plant in Pennsylvania travels to New Jersey by way of the prevailing wind, a situation that provides exogenous variation in the level of sulfur dioxide in the downwind state.  We find that exposure to sulfur dioxide during pregnancy can increase the probability of having a VLBW baby by 26.7–28.6 percent.  Even at today’s relatively low levels of sulfur dioxide, thanks largely to the passage of the Clean Air Act of 1970, our estimates indicate that the benefit of pollution abatement can be significant, even for an affluent region, as in our study, which already has excellent access to health care.