OBJECTIVES : The Regional Greenhouse Gas Initiative (RGGI) is the first regulatory program to limit regional CO₂ emissions in the United States. Prior studies have shown the association between high concentrations of ambient air pollutants such as CO₂ and an increased risk of morbidity and premature mortality. This study aimed to examine the impacts of RGGI on death rates in infancy.

METHODS : This was a quasi-experimental study using a difference-in-differences (DID) approach. Nine northeastern states (i.e., RGGI states) have implemented RGGI since 2009 whereas all other states (i.e., non-RGGI states) have not participated in the RGGI program. Accordingly, we compared changes in mortality outcomes between RGGI states and non-RGGI states after the implementation of RGGI. Outcome measures were neonatal mortality rate (NMR), deaths under 28 days, and infant mortality rate (IMR), deaths under 1 year. We obtained the annual NMRs and IMRs from the National Vital Statistics System from 2003 through 2014 (6 years before and after RGGI implementation). Our multivariate regression models included a number of covariates such as GDP, residential population, average temperatures, median household income, total number of births, birth weight, birth rate of black babies, mother’s education level, and number of hospitals, all of which were obtained from the public sources.

RESULTS : Implementation of RGGI was associated with significant decreases in overall NMRs (a reduction of 0.41/1,000 live births) and male NMRs (a reduction of 0.43/1,000 live births). However, RGGI did not have a significant effect on female NMRs. Similarly, overall IMRs and male IMRs decreased significantly by 0.37/1,000 live births and 0.61/1,000 live births, respectively, after implementation of RGGI while female IMRs were not significantly affected by RGGI.

CONCLUSIONS : RGGI was associated with decreases in overall infant mortality and boy mortality through reducing air pollutant concentrations. Notably, the impact of this environmental policy on infant girls was much smaller.