Military training exercises, pollution, and their consequences for health.

Militaries around the world perform training exercises in preparation for war. We study the relationship between in utero exposure to military exercises (bombing) and early-life health outcomes, combining data on naval bombing exercises in Vieques, Puerto Rico, and the universe of births from 1990 to 2003. Using a differences-in-differences design, we find that the sudden end of bombing practices is associated with a 56-79% decrease in the incidence of congenital anomalies.