Living near roads with "stop-and-go" traffic may raise a baby's odds of wheezing, new research shows.

"Near" was less than 100 meters (109 yards) away. That's a little more than a football field's length.

Wheezing is a sign that the infant is having some difficulty breathing. It's caused by the rush of air through a narrowed airway.

Airways can narrow in response to a cold or irritants, such as traffic pollution. Wheezing can also be a sign of asthma.

"Our study illustrates that living within a football field's distance of 'stop-and-go' traffic puts infants at a higher risk of wheezing," says researcher Patrick Ryan, MS, in a news release.

He also found that living near highway traffic did not increase the risk of wheezing in infants less than a year old.

"Traditional wisdom told us that highway traffic was to blame. We now know that's not necessarily the case," says Ryan, who works in the University of Cincinnati's environmental health department.

Read WebMD's "Study Shows School Bus Pollution 'Shocking'"

Tracking Infant Wheezing

Traffic pollution has already been tied to kids' asthma.

But wheezing is a little different. Babies who wheeze don't always grow up with asthma, write the researchers.

Ryan's team concentrated on infant wheezing and traffic type. Data came from 622 babies younger than 1 year old. Fifty babies wheezed without a cold.

Traffic around the babies' homes, parental allergies, and other factors that can affect wheezing (such as smoking and pets) were noted.

Read WebMD's "Learn More about Wheezing"

Wheels and Wheezing

Wheezing was more common for infants living less than 100 meters from roads with stop-and-go traffic.

Those roads carried cars, buses, and trucks, with a speed limit under 50 miles per hour. The closer babies lived to those roads, the greater their odds of wheezing.

Wheezing was noted in 19 percent of babies living about half a football field away from such traffic. That's three times higher than those not living near stop-and-go traffic.

Living near moving traffic didn't raise babies' chances of wheezing as much. Braking and accelerating may release more pollutants than a steady pace, write the researchers.

"Living within 100 meters of stop-and-go bus and truck traffic was the most important risk factor for early infant wheeze," write the researchers.

"These results suggest that the distance from and type of traffic exposures are more significant risk factors than traffic volume for wheezing in early infancy," they write.

Wheezing was at least twice as common among black babies as in whites, regardless of where the black babies lived.

Read WebMD's "Pet Dogs May Keep Infants From Wheezing"

Asthma, Allergies to Be Studied

The researchers plan to track the kids' asthma and allergies in the future.

"During the first year of life, an infant's lungs and immune system are still developing," says Ryan. "Overexposure to harmful particulates at such a young age may play a role in the development of allergic conditions."

By Miranda Hitti, reviewed by Michael W. Smith, MD

SOURCES: Ryan, P. The Journal of Allergy and Clinical Immunology, August 2005. News release, University of Cincinnati. WebMD Medical News: "Traffic Pollution Tied to Asthma in Kids."