Sprays may irritate the airways, say the researchers

A study found using household cleaning sprays and air fresheners as little as once a week raised the risk of asthma.

Heavy use of such products has already been linked with occupational asthma, but the latest work suggests occasional use in the home also poses a threat.

The Spanish study of more than 3,500 is published in the American Journal of Respiratory and Critical Care Medicine.

We do already know that air fresheners and bleach trigger symptoms in people who already have asthma

Victoria King of Asthma UK

The risk of developing asthma increased with frequency of cleaning and the number of different sprays used.

Spray air fresheners, furniture cleaners and glass cleaners carried the highest risk.

Exposure to cleaning products could account for as much as 15%, or one in seven adult asthma cases, the researchers suggest.

On average, the risk was 30-50% higher in people regularly used the sprays than in others.

And the incidence of physician-diagnosed asthma was higher among those using sprays at least four days per week

Irritants

The study authors, Dr Jan-Paul Zock and colleagues from the Municipal Institute of Medical Research in Barcelona, said work was needed to determine the biological mechanism behind the increased risk.

It may be that sprays contain irritants specific to asthma, they suggest.

Dr Kenneth Rosenman, professor of occupational and environmental medicine at Michigan State University, said: "Clinicians should be aware of the potential for cleaning products used in the home to cause respiratory symptoms and possibly asthma."

Victoria King of Asthma UK said: "We know that up to 25% of people exposed to chemicals, including cleaning sprays, at work will go on to develop occupational asthma.

"This report also highlights significant findings regarding the link between asthma and the use of spray cleaning products in the home. Although further research is needed, we do already know that air fresheners and bleach trigger symptoms in people who already have asthma.

"For anybody concerned about developing asthma as a result of using cleaning products we recommend they speak to their doctor or call our advice line on 08457 01 02 03."

The UK Cleaning Products Industry Association said: "The safety of consumers is the highest priority of our industries and the safety of our products is regularly checked and subject to rigorous controls, as well as stringent European legislation."

A spokesman stressed that cleaning product use has not been demonstrated to cause asthma.