Johns Hopkins scientists report that high levels of a
noxious gas from stoves can be added to
the list of indoor pollutants that aggravate asthma
symptoms of inner-city children, especially
Nitrogen dioxide, an irritating and toxic form of
nitrogen oxide gas, is most prevalent in
industrial zones but also found at higher levels in poor
homes with unvented gas stoves.
In a report in the October issue of Environmental
Health Perspectives, Johns Hopkins
researchers say asthma flare-ups were directly related to
high concentrations of NO2 in the inner-city homes they
Specifically, the researchers compared the frequency
and intensity of coughing, wheezing,
shortness of breath and chest tightness to NO2 levels
inside the inner-city homes of 150 Baltimore
City 2- to 6-year-olds. Eighty-three percent of the
households had gas stoves, 72 percent were
heated by natural gas, and 14 percent used gas stoves for
heating in the winter. Forty-two percent of
the households had annual incomes under $25,000.
Across the board they found that the pollutant
worsened day and night symptoms. Each 20-
point increase in nitrogen dioxide levels led to 10 percent
more days of cough and 15 percent more
days with limited speech due to wheezing. Use of gas
stoves, space heaters or home heating with a
stove or an oven, either in combination or alone, each
drove up nitrogen dioxide concentrations.
"Because using stoves as heat sources is a hallmark of
urban poverty, our study tellingly points
to how profound and direct the effects of purely social and
environmental factors can be on a child's
health," said lung expert Nadia Hansel, a lead researcher
on the report. "Doctors caring for children
with asthma should always inquire about the home's heating
and cooking appliances and urge those
using gas-based stoves and space heaters to switch to
electric heating and cooking, if possible, or at
least properly vent the exhaust gases.
"Inner-city preschoolers appear especially vulnerable
because they spend most of their time
indoors and in homes with high levels of nitrogen dioxide,"
said study senior investigator and pulmonary
expert Gregory Diette. "We knew that but still we were
disturbed by what we saw: As nitrogen
dioxide levels crept up, so did the frequency and severity
of these kids' symptoms."
Asthma is the most common pediatric chronic illness,
affecting 6.2 million children in the United
States. Severe illness is most prevalent in inner-city
children, doctors say, because of poor access to
regular health care and disproportionate exposure to indoor
allergens such as mouse and cockroach
dander, dust, cigarette smoke and automobile fumes.
In an earlier study of inner-city children with
Hopkins Children's Center
researchers found that even mild asthma among this
vulnerable group appears to be more
unpredictable than ever, with recommendations for at least
four checkups a year in such children to
ward off dangerous flare-ups. Current asthma guidelines
call for follow-up of one to six months after
Co-investigators in the study were Patrick Breysse,
Elizabeth Matsui, Meredith McCormack,
Jean Courtin-Brosnan, D'Ann Williams, Jennifer Moore and
Jennifer Cuhran, all of Johns Hopkins.
The research was funded by the National Institute of
Environmental Health Sciences, the
National Heart, Lung and Blood Institute and the
Environmental Protection Agency.