Indoor NO2 exposure worsens kids asthma

Indoor exposure to nitrogen dioxide (NO2) from gas-fueled stoves, even at levels well below the Environmental Protection Agency outdoor standard, may cause respiratory symptoms in asthmatic children living in multi-family housing units, new research suggests.

Chronic exposure to indoor NO2 is a public health concern, in part, because more than half the households in the US have a source of NO2, usually a gas-fueled cooking appliance, lead author Dr. Kathleen Belanger and colleagues, from Yale University in New Haven, Connecticut, note.

To determine if indoor NO2 exposure may incite respiratory symptoms in children with asthma, the researchers measured home levels of the gas and evaluated symptoms in 728 subjects.

After accounting for a variety of potential confounding factors, living in a multi-family home with a gas stove or elevated NO2 levels was significantly associated with asthma symptoms, the team reports in the American Journal of Respiratory and Critical Care Medicine.

Among subjects living in multi-family housing, gas stove exposure raised the risks of wheezing and dyspnea (difficulty breathing) more than twofold, and chest tightness more than fourfold.

In a statement, Belanger said: "This is the largest study to examine the effects of NO2 on children with asthma. The study population was quite diverse and included both white and non-white children living in single-family and multi-family homes, and children living in urban and suburban environments."

"The association between NO2 and respiratory symptoms was limited to children in multi-family housing," Belanger noted.

SOURCE: American Journal of Respiratory and Critical Care Medicine, February 2006.