Exposures to Particulate Matter from the Eruptions of the Puyehue Volcano and Birth Outcomes in Montevideo, Uruguay

BACKGROUND The ashes and dust resulting from the 2011 eruptions of the Puyehue volcano in Chile more than doubled monthly averages of PM10 concentrations in Montevideo, Uruguay. Few studies have taken advantage of natural experiments to assess the relationship between ambient air pollutant concentrations and birth outcomes. OBJECTIVES In this study we explored the effect of particulate matter with diameter of ≤ 10 μm (PM10) on perinatal outcomes in Uruguay, a middle-income country in South America with levels of PM10 that in general do not exceed the recommended thresholds. The analyzed outcomes are preterm birth, term birth weight, and term low birth weight. METHODS We took advantage of the sharp variation in PM10 concentrations due to the Puyehue eruptions to estimate the associations between mother's exposure to PM10 in each trimester of pregnancy and perinatal outcomes. We use birth registries for 2010-2013 and control for covariates, including maternal and pregnancy characteristics, weather, co-pollutants, and calendar quarter and hospital indicators. RESULTS A 10-μg/m3 increase in exposure to PM10 during the third trimester was associated with a higher likelihood of a preterm birth [odds ratio (OR) = 1.10; 95% CI: 1.03, 1.19]. The association was robust to different model specifications, and increased with categorical exposure levels (OR for third-trimester PM10 ≥ 70 vs. < 30 μg/m3 = 5.24; 95% CI: 3.40, 8.08). Exposures were not consistently associated with birth weight or low birth weight among term births, though second-trimester exposures were associated with higher birth weight, contrary to expectations. CONCLUSIONS Taking advantage of a natural experiment, we found evidence that exposure to high levels of PM10 during the third trimester of pregnancy may have increased preterm births among women in Montevideo, Uruguay. Citation: Balsa AI, Caffera M, Bloomfield J. 2016. Exposures to particulate matter from the eruptions of the Puyehue Volcano and birth outcomes in Montevideo, Uruguay. Environ Health Perspect 124:1816-1822; http://dx.doi.org/10.1289/EHP235.