A health expert has issued a warning over the link between cleaning sprays and asthma.
Chlorine, bleach, disinfectants and other cleaning agents are fuelling a rise in asthma at home and at work, he said.
Jan-Paul Zock pointed to growing evidence that cleaning products can spark asthma and make existing symptoms worse.
Professional cleaners and health workers who use products in hospitals are particularly vulnerable, he added.
Addressing a European allergy conference in London, Dr Zock said studies had already found higher rates of asthma among caretakers, cleaners, housekeepers and nurses.
Breathing in bleach, ammonia, decalcifiers, acids, solvents and stain removers more than once a week was linked to a 20% rise in asthma or wheezing, Dr Zock said.
People who use cleaning products frequently are most at risk, as are those who use them for long periods. How strong a product is, together with how well a room is ventilated, also affects the risk.
Dr Zock said more studies were needed on people's exposure at home, which can be difficult to track. However, he said, many people at home could be at risk.
“The number of people at risk is very large,” said Dr Zock, from the Centre for Research in Environmental Epidemiology in Barcelona. He added that some people were more susceptible to the effects than others.
“Not only those who have cleaning jobs or whose work involves cleaning are at risk, but we also need to consider the ubiquitous use of cleaning products at home,” he said.
Other research presented at yesterday's conference — of the European Academy of Allergy and Clinical Immunology — suggests it may be possible to prevent asthma in high-risk babies by avoiding certain foods and dust mites in the first few months of life.
Experts from the David Hide Asthma and Allergy Research Centre on the Isle of Wight have monitored 120 children since 1990.
In the study, babies up to one avoided dairy products, soya and nuts, as did their breastfeeding mothers. The 58 babies slept on vinyl mattresses and covers and the mite-control spray acracide was used.
Dr Martha Scott, who led the study, said children had less allergic reactions aged one, two, four and eight.
In the UK, 5.4 million people are affected by asthma.