Household cleaning products are as a bad for lung function as smoking, a new study has shown.

In a new report women who worked as cleaners or regularly use cleaning sprays for 20 years were found to have lung decline equivalent to smoking 20 cigarettes a day over the same period.

They were also 40 per cent more likely to develop asthma.

"When you think of inhaling small particles from cleaning agents that are meant for cleaning the floor and not your lungs, maybe it is not so surprising after all," said lead author Øistein Svanes of the University of Bergen, Norway, who carried out the research on more than 6,000 cleaners over 20 years.

"The take home message of this study is that in the long run cleaning chemicals very likely cause rather substantial damage to your lungs.

"These chemicals are usually unnecessary. Microfibre cloths and water are more than enough for most purposes."