When good fences aren't enough: The impact of neighboring air pollution on infant health.

The Clean Air Interstate Rule (CAIR) mandated the reduction of power plant emissions in the eastern United States. Starting in March 2005, this policy greatly reduced exposure to a specific form of pollution—fine particulate matter—in neighboring downwind counties. Using data from the 1995 to 2013 waves of the U.S. Natality Detail Files, we investigate the impact of this reduced exposure on birth outcomes including premature birth, birth weight status and infant mortality. Our most consistent finding is that the CAIR reduced premature birth, particularly among women aged thirty-five and older, those who experienced clinically-designated "risky" pregnancies, and those who gave birth to female newborns. We also find a substantial reduction in infant mortality for newborns whose mothers experienced "risky" pregnancies. Taken together, our findings suggest that policy-induced reductions in exposure to fine particulate matter may lead to improved birth outcomes among those mothers and newborns most at risk. [ABSTRACT FROM AUTHOR]