Same Environment, Stratified Impacts? Air Pollution, Extreme Temperatures, and Birth Weight in South China
61 Pages Posted: 2 Feb 2021 Last revised: 25 Oct 2021
Date Written: October 24, 2021
This paper investigates whether associations between birth weight and prenatal ambient environmental conditions--pollution and extreme temperatures--are mediated by 1) inequality in socioeconomic endowments measured by maternal education; 2) inequality in children's innate health endowments; and 3) interactions between these two dimensions of inequalities. We link birth records from Guangzhou, China, during a period of high pollution, to ambient air pollution (PM10 and a composite measure) and extreme temperature data. We first use mean regressions to test whether, overall, maternal education is an "effect modifier" in the relationships between ambient air pollution, extreme temperature, and birth weight. We then use conditional quantile regressions to test for effect heterogeneity according to the unobserved innate vulnerability of babies after conditioning on other confounders. The results show that 1) the negative association between ambient exposures and birth weight is twice as large at lower conditional quantiles of birth weight as at the median; 2) the protection associated with a college-educated mother with respect to pollution and extreme heat is substantial: up to 0.34 standard deviations of birth weight; 3) this protection is amplified under more extreme ambient conditions and for infants with greater unobserved innate vulnerabilities.
Keywords: air pollution, birth weight, maternal education, extreme temperatures, China
JEL Classification: I14, J1, Q53, Q54
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