Contact: Dave DeFusco, Director of Communications, 203-436-4842

The exposure of pregnant women to air pollution can increase their risk of having low-birth-weight infants, according to a Yale study.

Researchers at the Yale School of Forestry & Environmental Studies and the Yale School of Medicine found that the higher the level of exposure to nitrogen dioxide, carbon monoxide and particulate matter (PM2.5 and PM10), the greater the risk of having lower-weight infants.

The researchers investigated the exposure of pregnant women for 358,504 births from 1999 to 2002 in 15 Connecticut and Massachusetts counties.

The Yale study results imply that even low levels of air pollution can have harmful effects. Average concentrations for all pollutants in the study were below the Environmental Protection Agency’s health-based regulatory standards, called the National Ambient Air Quality Standards. Further, exposure to PM2.5, a fine particulate matter that is a component of vehicle exhaust, had a greater negative effect on infants of black mothers than those of white mothers.

“This study indicates that some populations may face disproportionate health burdens of air pollution,” said Michelle Bell [profile], assistant professor of environmental health at Yale’s environment school and co-author of the study with Keita Ebisu and Kathleen Belanger, both of the Yale School of Medicine.

Other studies have linked low birth weight to a higher risk of infant and childhood mortality, coronary heart disease and other health problems.

The study, “Ambient Air Pollution and Low Birth Weight in Connecticut and Massachusetts,” is accepted for publication in Environmental Health Perspectives and is available here.