Exposure to Outdoor Air Pollution and Birth Outcomes -Evidence from Sao Paulo's Western Region Project

摘要

Background: While a growing literature has highlighted the negative associations between maternal exposure to NOx and PM pollution and birth weight, evidence on the effect of ambient air pollution on prematurity remains limited. We use new data on street level air pollution to estimate the associations between NOx and birth outcomes in Sao Paulo, Brazil. Methods: 5,542 birth records from children born at the University Hospital of Sao Paulo between April 2012 and March 2014 were linked to street level NOx and PM2.5 emissions using residential addresses. Primary outcomes analyzed were prematurity (gestational age < 37 weeks), low birth weight (< 2500 grams) and being small for gestational age (SGA). Adjusted and unadjusted linear models were used to assess the associations between prematurity, gestation-adjusted weight and child development overall, as well as by gender. Results: In fully adjusted regression models, we find that each unit increase in the natural logarithm of NOx emissions is associated with a 60 percent increase in the odds of low birth weight (95% CIs [1.163, 2.204]), and a 39 percent increase in the odds of prematurity (95% CI [1.016, 1.905]). We do not find any associations between NOx exposure and SGA. Conclusions/Interpretation: The results presented in this study suggest that residential exposure to NOx emissions (a proxy estimate of traffic-derived pollution) may constitute a major risk factor for both low birth weight and prematurity in Sao Paulo and similarly large urban areas. The potential health benefits of lowering local emission levels seem sizeable.