The epidemiological study, the first to investigate the effects of cleaning products on occasional users rather than occupational users, was published in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

"The relative risk rates of developing adult asthma in relation to exposure to cleaning products could account for as much as 15 percent, or one in seven of adult asthma cases," said lead author Jan-Paul Zock of the Center for Research in Environmental Epidemiology at the Municipal Institute of Medical Research in Barcelona, Spain.

More than 3,500 subjects in 10 European countries were tested for asthma symptoms and interviewed about the number of times per week they used cleaning products.

The risk of developing asthma increased with frequency of cleaning and number of different sprays used, but on average was about 30 percent to 50 percent higher in people regularly exposed to cleaning sprays.

The researchers said cleaning sprays, especially air fresheners, furniture cleaners and glass-cleaners, had a particularly strong effect.