Atmospheric Air Pollution and Birth Weight

We examine the impact of air pollution (PM10 measure) on birth weight, probability of being Low Birth Weight (less than 2500 grams), and Very Low Birth Weight (less than 1500 grams). We exploit the unique interaction between rainfall and pollution accumulation in Santiago, Chile to pin down the causal relationship between atmospheric pollution and birth outcomes. While controlling for seasonality, we find that higher rainfall leads to days with substantially less pollution, specially in the winter months. Using rainfall during various times of the gestational period as an instrument for pollution exposure, we find that atmospheric pollution (PM10) has a substantial effect on birth weight - a one standard deviation increase in pollution decreases birth weight by 125 grams. We estimate that if pollution were reduced by 1 standard deviation on average, the per cohort gains (via increased lifetime earnings) to the Chilean economy are around USD 72 million (0.04% of GDP)