Asthma triggered by allergens and pollution has reached epidemic proportions in some areas. In 2003, a study found that 1 in 4 children living in central Harlem suffers from the disease. Because outdoor pollutants are hard to control, researchers from the University of Arizona went into homes of asthmatic children in cities around the country, to see whether cleaning up could make their asthma better.

What the researchers wanted to know: Does cleaning up the home help children who have asthma?

What they did: More than 800 children between the ages of 5 and 11 living in impoverished neighborhoods in Boston, Chicago, Dallas, New York City, Seattle, and Tucson, Ariz. were examined and tested for sensitivity to common household allergens such as dust mites, mold, cockroaches, and pet dander. Teams inspected all of the children's homes for allergens, and collected and tested dust from the children's bedrooms. Then, the researchers split the children into two groups and gave one group a year of training sessions in which research assistants visited the children's homes and showed them how to reduce dust, mold, rodent and insect allergens, and exposure to second-hand smoke. Trainers also gave parents air filters, allergen-preventing bed covers, vacuum cleaners fitted with air filters, and pest control devices. Interviewers called all the families every two months during the training year and for an additional year afterwards and asked about the symptoms of asthma.

What they found: Children in the cleaning group had significantly fewer days of symptoms per week during the year of training and for a year after that than did children who did not receive the training. The children in clean houses improved about as much as other studies have found for children who take inhaled corticosteriods, commonly used to treat asthma. Over the two years of the study, children whose homes were cleaned up spent an average of 34 fewer days wheezing due to asthma than children who had no help. Training substantially reduced the number of allergens in the home, though in the year after the study dust and dander began to appear again.

What it means to you: This study shows that a little vacuuming and an air filter can go a long way towards improving a child's asthma symptoms. The study found that reducing asthma triggers in the home had the same effect as taking medications—without the side effects. By putting allergen-preventing bed covers on the beds, regularly cleaning the floor with air-filter vacuums, setting up an air purifier in the child's room, and using pest control devices, children's asthma could improve significantly. For this study, the cost of treating each child in the intervention group was $1,500 to $2,000, though any kind of clean up, especially in the area where the child sleeps, should help.

Caveats: Because the homes of children in the intervention group were visited so frequently, the reduction in asthma symptoms could be at least partially caused because parents paid more attention to the child's condition. This caveat is supported by an overall reduction in the days of symptoms per week seen in both groups during the years of the study—the increased phone contact and attention given to the child's asthma may have prompted parents to try to do things to try to reduce attacks.

Find out more: A page on the American Academy of Allergy, Asthma, and Immunology's website gives information about allergic asthma triggers and treatments.

The Environmental Health Watch has tips to create an "asthma healthy house".

Read the article: Morgan, W.J. et al. "Results of a Home-Based Environmental Intervention Among Urban Children With Asthma." New England Journal of Medicine. Sept. 9, 2004, Vol. 351, No. 11, pp. 1068–1080.

Abstract online: http://content.nejm.org