Air pollution and infant health: What can we learn from California's recent experience?

We examine the impact of air pollution on infant death in California over the 1990s. Our work offers several innovations: first, most previous studies examine populations subject to far greater levels of pollution. Second, many studies examine a single pollutant in isolation. We examine three criteria pollutants in a common framework. Third, we use rich individual-level data and pollution measured at the weekly level. Our most novel finding is a significant effect of CO on infant mortality: we find that reductions in carbon monoxide over the 1990s saved approximately 1000 infant lives in California.