No deep breathing: air pollution impedes lung development.

Spending one's childhood in a community with polluted air stalls lung development roughly as much as does having a mother who smokes, according to a study of children growing up in southern California.

That finding lengthens the list of negative effects on health that stem from bad air (SN: 8/2/03, p. 72), but it also suggests that antipollution measures could prevent deficits in pulmonary development.

Adolescence is prime growing time for lungs. To evaluate the effects of air pollution during this important period, W. James Gauderman of the University of Southern California in Los Angeles and his colleagues in 1993 tested the lung capacity of 1,759 fourth graders in a dozen southern California communities, including some notably clean areas and some of the most polluted towns in the United States.

Then, through 2001, the researchers annually repeated the test on as many of the original volunteers as they could locate. Moreover, they recorded information on each child's health and exposure to tobacco smoke.

Gauderman and his colleagues also took air samples, which they used to estimate concentrations of various air pollutants in each participating community.

Between the ages of 10 and 18 years, most of the boys doubled their lung function, and girls increased theirs by about two-thirds. About 4 percent of the 18-year-olds fell at least 20 percent short of the value that the scientists had predicted for them, taking into account such factors as their sex, size, tobacco exposure, and any asthma.

Teens who had grown up in towns with the dirtiest air were up to five times as likely to have lower-than-expected lung function as were kids in the cleanest communities. The average differences in lung capacity between the most-polluted and cleanest-air towns were similar to those previously observed among children whose mothers did and didn't smoke, respectively.

Airborne carbon, nitrogen dioxide, acid vapors, and particulate matter contributed to the diminished lung capacity, Gauderman and his colleagues report in the Sept. 9 New England Journal of Medicine. In southern California, they note, those pollutants come mainly from cars and trucks.

The entire population faces long-term harm from modest air pollution, says C. Arden Pope III of Brigham Young University in Provo, Utah. The study indicates that boys and girls, teen smokers and nonsmokers, and kids with and without asthma are equally susceptible, he says.

"Even relatively small amounts of air pollution have fairly large, long-term effects on pulmonary health," Pope says. The harm to young lungs appears proportional to the pollutants' concentrations, no matter how low they fall. Any worsening of air quality, even within currently permitted ranges, is thus likely to harm public health, he says.

On the other hand, air-quality improvements could produce health benefits. "Extremely high concentrations of air pollution remain in many areas of the world, and decreasing these concentrations offers substantial opportunities for disease prevention," Pope says.