Impacts of the Regional Greenhouse Gas Initiative (RGGI) on infant mortality: a quasi-experimental study in the USA, 2003–2014

OBJECTIVES: The Regional Greenhouse Gas Initiative (RGGI) is the first mandatory market-based regulatory programme to limit regional carbon dioxide (CO(2)) emissions in the USA. Empirical evidence has shown that high concentrations of ambient air pollutants such as CO(2) have been positively associated with an increased risk of morbidity (eg, respiratory conditions including asthma and lung cancer) and premature mortality. The purpose of this study was to examine the impacts of RGGI on death rates in infancy. DESIGN: A quasi-experimental difference-in-differences design. SETTING AND PARTICIPANTS: We estimated the impacts of RGGI on infant mortality from 2003 through 2014 in the USA (6 years before and after RGGI implementation). Our analytic models included state- and year-fixed effects in addition to a number of covariates. OUTCOME MEASURES: Death rates in infancy: neonatal mortality rates (NMRs), deaths under 28 days as well as infant mortality rates (IMRs), deaths under 1 year. RESULTS: Implementation of RGGI was associated with significant decreases in overall NMRs (a reduction of 0.41/1000 live births) and male NMRs (a reduction of 0.43/1000 live births). However, RGGI did not have a significant effect on female NMRs. Similarly, overall IMRs and male IMRs decreased significantly by 0.37/1000 live births and 0.61/1000 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. Of note, the impact of this environmental policy on infant girls was much smaller.