Air pollution poses a risk to pregnant women and their babies, according to a study published recently in the science journal, Environmental Health. Traffic-generated air pollutants, especially polycyclic aromatic hydrocarbons (PAH), are linked to a 30-percent increase in premature births.
For nearly two years investigators looked at 100,000 births that occurred within a five mile radius of air quality monitoring stations in Los Angeles, California. Researchers compared exposure to specific air pollutants and length of gestation, making adjustments for variables such as maternal age, ethnicity, education and whether mothers had given birth before.
Air quality information was derived from three separate sources, and included data regarding concentrations of carbon monoxide, nitrogen dioxide, ozone, and fine particulate matter.
Some of the pollutants were specific to particular areas, due to industry and urbanization. Overall exposure to widespread pollutants, such as PAH, however, was clearly linked to a 30 percent increase in the risk of premature birth.
Exposure to other toxins, such as benzene, and fine particulates from diesel engines, was linked to a 10-percent increased risk. Exposure to ammonium nitrate particles was associated with a 21-percent increased risk of premature birth.
Investigators noted that local weather played a role in exposure, as did location. Women living in coastal areas, where winds presumably help disperse air pollution, experienced lower risks than women in urban areas.
"Air pollution is known to be associated with low birth weight and premature birth. Our results show that traffic-related PAH are of special concern as pollutants, and that PAH sources besides traffic contributed to premature birth," said Dr Beate Ritz.
"The increase in premature birth risk due to ammonium nitrate particles suggests secondary pollutants are also negatively impacting the health of unborn babies. To reduce the effects of these pollutants on public health, it is important that accurate modeling of local and regional spatial and temporal air pollution be incorporated into pollution policies."
Premature delivery (preterm birth) is often associated with low birth weight of the baby. Both conditions are associated with increased risks of a host of developmental problems, including respiratory distress, heart problems, gastrointestinal difficulties and increased risk of infections.