Gasp! Ozone limits don't protect babies.

In healthy infants, even ozone concentrations well below those allowed by federal law trigger asthmalike symptoms, a new study shows.

The finding indicates that federal limits on this pervasive pollutant, a prime constituent of smog, don't protect infants "from rather severe respiratory symptoms," says epidemiologist Elizabeth W. Triche of the Yale University School of Medicine.

Triche's team recruited 691 women with 3-to-5-month-old infants from nonsmoking households around Roanoke, Va. Sixty-one moms had asthma, signaling that their babies were at high risk for developing the disease. The researchers collected daily respiratory data, as reported by the mothers, on all the children for 83 days in summer--the peak ozone season--and then correlated the infant's symptoms with outdoor measurements of several air pollutants.

As ozone values climbed, so did the risk of wheezing and troubled breathing in the babies, Triche's team reports in the June Environmental Health Perspectives. The other pollutants, such as fine particulates, didn't show that correlation.

For each 11.8 parts per billion (ppb) increase in average daily concentrations in ozone, the likelihood of wheezing increased by 41 percent in all the infants and 91 percent in those with asthmatic morns. Each 11.8 ppb increase in ozone also increased the risk of labored breathing by almost 30 percent for all kids and more than doubled it in babies with asthmatic moms.

These findings dovetail with those that Triche's group reported 3 years ago in 6-to-12-year-old children. The big difference: Those children had asthma. In the new infant study, she notes, "children were not asthmatic."--J.R.