March 11, 2003 (Denver) -- Newborns who live in houses in which gas stoves are used or are located near busy roads may be at increased risk of developing dust mite allergies, new research suggests.
Rob T. van Strien, PhD, of Yale University, and colleagues investigated the link between exposures to high levels of a gas called nitrogen dioxide (NO2) and the risk of dust mite, dog, and cat allergy.
The researchers presented their findings at the 60th Anniversary Meeting of the American Academy of Allergy, Asthma, and Immunology (AAAAI) on Monday.
According to van Strien, NO2 forms when anything is burned -- the flame interacts with the nitrogen in the air.
"It's typically found at highest levels in houses that use gas stoves," van Strien said. "In fact, only 4% of houses that did not use gas stoves had levels in the high category, but almost 60% of houses that cooked with gas did," he noted during a news conference.
The gas is also found in car exhaust fumes, so any building near a busy street might have high levels also, he said.
The researchers measured the NO2 concentrations and the levels of dust mite, dog, and cat allergens in the homes of 806 infants in Connecticut and Massachusetts. They then counted the number of infants who showed symptoms of wheezing and coughing during the first year of life.
All the children had an asthmatic sibling and therefore were considered at high risk for developing asthma, van Strien noted.
The percentage of infants in homes with high NO2 concentrations who had respiratory symptoms increased with the amount of dust mite allergen present per gram of infant bed dust.
In those homes with high NO2levels and high dust mite levels, 100% of infants had respiratory symptoms, and these children were nearly nine times as likely to develop symptoms as those with low dust mite allergen levels, the researchers report.
In contrast, in homes with low NO2 concentrations (lower than 20 parts per billion) high levels of dust mite allergen did not cause a problem. In addition, respiratory symptoms did not increase in response to increasing levels of dog or cat allergens.
As for why NO2 might cause these problems, van Strien explained that the gasmight make the lining of the airways more vulnerable to the effects of some allergens. He advised that the best way to reduce NO2 levels is to not cook with gas.
"I don't think I would go and have my patients try to measure the NO2 levels in their homes," Kathleen A. Sheerin, MD, an allergist at the Allergy and Asthma Clinic in Atlanta and vice chairwoman of the AAAAI's public education committee, tells WebMD. But parents who are concerned may consider taking steps to lower NO2 concentrations.
Sheerin notes that people spend much more time indoors than outdoors. "The dust mite is a major allergen," she says, "so this is an interesting finding that we need to look at further."