Washington: Prenatal exposure to air pollution through the mother can be especially serious for asthmic children, says a new study.

Researchers looked at several pollutants, including carbon monoxide, nitrogen dioxide, ozone and particulate matter. Exposure to nitrogen dioxide during the first and second trimesters was tied with lower pulmonary function growth in both girls and boys.

"We found that prenatal exposures to airborne particles and the pollutant nitrogen dioxide adversely affect pulmonary (lung) function growth among asthmatic children between six and 15 years of age," said Amy Padula, post-doctoral fellow at the University of California - Berkeley, who led the study.

The study was conducted as part of the Fresno Asthmatic Children's Environment Study (FACES), which examines the influence of prenatal exposure to a number of ambient air pollutants on the growth of lung function during childhood and teen years in a high pollution area, said a university statement.

Researchers included repeated evaluations of 162 asthmatic children aged between six and 15 years and their mothers. The mothers' residences during pregnancy were geocoded and pollutant concentrations were obtained from the Aerometric Information Retrieval System supported by the US Environmental Protection Agency (EPA).

"This finding adds to the evidence that current air pollution levels continue to have adverse effects on human health," Padula said.

"Few studies have examined prenatal exposure to air pollution and subsequent lung function in childhood. These results suggest that we need to be doing a better job to reduce traffic-related air pollution," Padula added.

The study will be presented at the ATS 12 International Conference in San Francisco.