Chinese Yellow Dust and Korean Infant Health

Naturally-occurring yellow sand outbreaks, which are produced by winds flowing to Korea from China and Mongolia, create air pollution. Although there is seasonal pattern of this phenomenon, there exists substantial variation in its timing, strength and location from year to year. Thus, exposure to the intensity of air pollution exhibits significant randomness and unpredictability. To warn residents about air pollution in general, and about these dust storms in particular, Korean authorities issue different types of public alerts. Using birth certificate data on more than 1.5 million babies born between 2003 and 2011, we investigate the impact of air pollution, and the avoidance behavior triggered by pollution alerts on various birth outcomes. We find that exposure to air pollution during pregnancy has a significant negative impact on birth weight, the gestation weeks of the baby, and the propensity of the baby being low weight. Public alerts about air quality during pregnancy have a separate positive effect on fetal health. We show that Korean women do not time their pregnancy according to expected yellow dust exposure, and that educated women’s pregnancy timing is not different from those who are less-educated. The results provide evidence for the effectiveness of pollution alert systems in promoting public health. They also underline the importance of taking into account individuals’ avoidance behavior when estimating the impact of air quality on birth outcomes. Specifically, we show that the estimated impact of air pollution on infant health is reduced by half when the preventive effect of public health warnings is not accounted for.