TUESDAY, Oct. 12, 2004 (HealthDayNews) -- New research suggests that exposure to air pollution before birth and tobacco smoke after birth combine to damage the lung health of babies.
"Pollutants in our cities can affect children very early, prenatally and at age 1 or age 2, even before a child has asthma," said Dr. Rachel L. Miller, director of the Asthma Project at the Columbia Center for Children's Environmental Health in New York City. She is lead author of the study, which appears in the October issue of CHEST.
As part of their research for a series of studies, Miller and her colleagues gave air monitors -- about the size of backpacks -- to 303 pregnant Dominican and black women in New York City. All the women were nonsmokers. The machines analyzed how much they were exposed to pollutants called polycyclic aromatic hydrocarbons, which come from a variety of sources, including automobile exhaust, home heating systems and tobacco.
"There's certainly concern about the impact of these environmental exposures on pregnant woman and their offspring," especially in neighborhoods plagued by pollution from diesel exhaust, Miller said.
After the women's babies were born, the researchers asked the mothers about their children's health and their exposure to secondhand smoke.
At 1 year of age, the children of women exposed to high levels of the pollutants before birth and to tobacco smoke after birth were more likely to have developed coughs and wheezing. It's not clear how much more likely the exposed children were to develop the respiratory problems; Miller said the study wasn't designed to answer that question.
The researchers did find, however, that the combination of pollutants and tobacco smoke appeared to lead to more coughing and wheezing in boys, perhaps because they tend to have smaller airways.
At age 2, the children with the highest levels of exposure to the pollutants and tobacco smoke were more likely to have difficulty breathing and early symptoms of asthma.
The researchers don't know if the asthma symptoms will be permanent. "It's very difficult to diagnose asthma in a child until about age 5 or so," Miller said.
She said the researchers don't know why the pollutants and smoke might lead to respiratory problems, but it's possible they could stimulate the developing immune system. Asthma occurs when the body's immune system becomes overactive.
The exposure may even alter the DNA of children, Miller said. "How that translates to symptoms later on, nobody knows."
To learn more about the pollutants known as polycyclic aromatic hydrocarbons, visit the U.S. Centers for Disease Control and Prevention.