How to make bedrooms 'allergy-proof'

Dust mites feed on flakes of human skin

Simple household cleanliness could help banish one of the most common asthma triggers, say experts.

Careful vacuuming, changing bedding weekly and using special mattresses and pillows along with stream cleaning carpets and upholstery are all measures which will work.

The aim is to reduce the level of dust mite allergens.

Dust mites live in bedding, carpets, upholstery and curtains. They are tiny creatures which live of flakes of human skin.

Beds are a favoured home of the dust mite

But what triggers allergic diseases such as asthma and rhinitis (including hay fever) are the proteins found in the faeces of the mites - known as allergens.

US scientists from the National Institute of Environmental Health Sciences, the University of Washington and Harvard University looked at what measures families with low incomes could take to reduce these allergens in their homes.

They said millions of US homes had concentrations of dust mite allergens high enough to trigger asthma in susceptible people.

The British Allergy Foundation estimates 40% of the population suffer from an allergy, many of them suffering from a dust mite allergy.

Reuduced allergen levels

Thirty-nine households in Seattle, Washington were asked to use dust-mite proof covers for mattresses and pillows, wash bedding once a week in hot water and give their carpets and upholstery intensive cleaning.

We believe that the hot steam kills the mites and the vacuuming removes them from the carpets

Dr Darryl Zeldin,
National Institute of Environmental Health Sciences

It was found these measures all "significantly reduced" the levels of dust mite allergens, though some were better than others.

Vacuuming and steam cleaning reduced the level of allergens below that believed to be needed to trigger asthma symptoms.

But they were not low enough to prevent sensitisation.

This is the first stage in the development of an allergy and is the process of the body recognising a particular substance and developing an allergic reaction.

'Bare-bones existence'

Dr Darryl Zeldin, of the National Institute of Environmental Health Sciences (NIEHS), said: "We believe that the hot steam kills the mites and the vacuuming removes them from the carpets."

He added to reduce dust mite allergen levels further, people may need to remove carpets, and have leather or vinyl-covered furniture.

But Dr Zeldin added: "Such a bare-bones existence may be less desirable to the residents. In the meantime, more research is needed on inexpensive alternatives for maintaining long-term allergen control."

Muriel Simmons, chief executive of the British Allergy Foundation told BBC News Online: "This advice is very much what we've been saying for a long time."

She said bedding should be washed at 55C so that mites are killed, and that the BAF assessed vacuum cleaners and anti-allergy bedding for their effectiveness, with the best receiving a seal of approval.

She said soft toys should also be washed, because they too could harbour dangerous dust mites.

The research is published in the online version of the journal of NIEHS.