Regular use of household cleaning sprays and air fresheners may increase the risk of adult-onset asthma, according to a new study published in the American Journal of Respiratory and Critical Care Medicine.

Researchers analyzed data from the European Community Respiratory Health Survey, which collected epidemiological data at 22 centers in 10 countries. They followed this up with face-to-face interviews of 3,503 people who did the cleaning in their home and were free of asthma when the study began. Participants answered questions about the frequency of their use of 15 kinds of cleaning products. The researchers then followed up nine years later, using an interview to determine the participants' current asthma and wheeze levels, and the occurrence of physician-diagnosed asthma and allergy.

Those who used cleaning sprays at least once per week were 50 percent more likely to have increased asthma symptoms, wheeze, or asthma medication use in nine years than those who used such products less frequently. Those who used sprays at least four times per week were significantly more likely to have been diagnosed with asthma by a physician than those who used them less frequently. The strongest association was found with air fresheners, glass cleaners and furniture-cleaning sprays.

The researchers found no association between the use of non-spray cleaners, such as solvent stain removers and washing powders, and the incidence of asthma. There was also no apparent asthma increase associated with infrequently used spray products, such as oven cleaners.

The researchers concluded that exposure to cleaning products may be responsible for as many as one in seven cases of adult-onset asthma.

In an accompanying editorial, Kenneth D. Rosenman of Michigan State University noted that there is no legal requirement for companies to test products for the tendency to produce certain categories of allergic reactions, including asthma.