Caution, drivers! Children present: Traffic, pollution, and infant health

We show the effect of mobile source traffic pollution on infant mortality, both directly and through the channel of airborne particulate matter and carbon monoxide. We show higher levels of local traffic density lead to increased weekly infant mortality rates, and explore variation in effects by distance from traffic source, weather conditions, and infant subgroups. Direct effects of traffic are highly localized and substantially more detrimental to premature and low birthweight infants. We next build an instrumental variables approach that exploits the relationship between traffic and ambient weather conditions, and show particulate matter still has large impacts on weekly infant mortality rates even at today’s lower levels. We also find suggestive evidence of large negative effects for carbon monoxide, though results are imprecise. Finally, we formally investigate the sensitivity of our estimates to the presence of non-classical measurement error in local pollution, and show IV results are robust to such concerns. ∗Thanks to Janet Currie, Matthew Neidell, seminar participants at UC Davis, UC San Diego, and the University of California Energy Institute, and attendants of the NBER Summer Institute and Toxic Substances Research & Teaching Program Symposium (TSR&TP). Knittel gratefully acknowledges financial support from the University of California Energy Institute and UC Davis Institute of Transportation Studies. Sanders gratefully acknowledges funding from the UC Davis Institute of Governmental Affairs, the UC Davis Institute of Transportation Studies, and the TSR&TP through the Atmospheric Aerosols and Health (AAH) Lead Campus program. Knittel: William Barton Rogers Professor of Energy Economics, Sloan School of Management, Director of the Center for Energy and Environmental Policy Research, MIT and NBER, email: [email protected]. Miller: Department of Economics, University of California, Davis and NBER, email: [email protected]. Sanders: College of William & Mary, email: [email protected].