CHICAGO — Household cleaning sprays are meant to improve the indoor environment, but new research suggests they may actually contribute to new-onset adult asthma.
Aerosol cleaning sprays were associated with an increased risk for new asthma symptoms or medication use (relative risk 1.49) and for wheezing (RR 1.39) among 3,503 asthma-free adults, aged 20–44 years, surveyed in 10 European countries. If four or more sprays were used per week, the risk for new physician-diagnosed asthma increased (RR 2.11). No risk was detected from cleaning products not sprayed (Am. J. Respir. Crit. Care Med. 2007;176:735-41).
“I can't say if it pertains to children, but it seems logical to me,” Dr. Dennis R. Ownby said of the findings during a meeting sponsored by the American Academy of Pediatrics.
He highlighted the study to illustrate the importance of indoor air quality and respiratory health, particularly now that many Americans spend the majority of their time indoors. Pets and pests are known allergens, but it's important also to consider other common indoor air pollutants such as air fresheners, candles, sprays, stoves, and fireplaces. Cigarettes, fumes from dry cleaned clothes, and house paint also are sources of volatile organic compounds (VOCs) that can irritate lungs.
In a study comparing VOC exposure among 88 children with asthma and 104 age-matched controls (aged 6 months to 3 years), cases were exposed to significantly higher VOC levels than controls. For every 10-unit increase in the concentration of toluene and benzene (mcg/m
Dr. Ownby, chief of the allergy-immunology section and professor of pediatrics and medicine at the Medical College of Georgia, Augusta, also ran through some of the most common questions patients ask regarding efforts to reduce indoor irritants. Those questions include the following:
▸ Will steam cleaning carpets reduce allergens? No benefit was identified in the only controlled study to evaluate this issue. Moreover, it's the wrong way to go, Dr. Ownby said. To remove dust mites and pet allergens, it's best to remove carpeting from the home, particularly if it's laid on concrete floors, in which case the coolness of the floor and indoor humidity work to create a huge reservoir of allergens.
▸ Will washing a cat make it nonallergenic? Washing the cat or removing it from the home for short periods of time does little to improve air quality because it takes 12–16 weeks to reduce cat allergen levels down to the level of a house without a cat.
If removing the pet from the home is not an option, Dr. Ownby suggested keeping it out of the bedroom, keeping the bedroom door closed, and removing upholstered furniture and carpets from the home.
▸ Will a humidifier help control allergens? A study of 3,535 school children in southern California identified 256 (7%) new cases of asthma when the children were followed for 5 years or until graduation. The biggest risk factorfor the development of asthma was the presence of a humidifier in the home (RR 1.7)—beating out the presence of any pet (RR 1.6) or the family dog (RR 1.4) (Epidemiology 2002;13:288-95).
Dr. Ownby suggested reducing the indoor humidity to below 60%, with the optimal setting being 30%–50%.
▸ Can I keep pets if I use a HEPA air cleaner? Dr. Ownby does not recommend air filters for patients with pet allergens. He cited a study in which 35 cat-allergic patients (aged 18–65 years) with asthma or rhinitis who had one or more cats in the home were randomized to use air cleaners with or without HEPA filters. Despite applying an impermeable mattress cover, removing cats from the bedroom, and running the cleaners 90% of the time, after 6 months there was no significant difference between the two groups in nasal or chest symptoms, peak flow rates, sleep disturbance, medication use, or settled dust levels (Am. J. Respir. Crit. Care Med. 1998;158:115-20).
Dr. Ownby suggests that families who are interested in reducing irritants in their homes should minimize exposure to smoke from cigarettes or incense, sprayed products, products with strong odors including air fresheners, and unvented combustion sources. Allergen control should include eliminating the source or blocking exposure, reducing humidity and allergen reservoirs, and improving ventilation.
“We just don't ventilate our homes nearly as well as we should,” he said.
Dr. Ownby reported receiving research support from the National Institutes of Health and serving as a consultant to CarboNix, LLC.