PEOPLE with asthma and allergies are much more likely to be exposed to allergens in their living areas and outside than in their bedroom.
New Australian research counters the long-held belief that the bed is the most important site for asthma exposure-triggering symptoms.
It used a clip-on dust prototype mite exposure sampler that provided a continuous measurement day and night.
The research suggests allergens on clothing could play a bigger role than previously thought.
Researchers at the Woolcock Institute of Medical Research found only about 10 per cent of total daily exposure occurred while sleeping in bed, with 50 per cent occurring elsewhere in the house and 40 per cent outside the home.
"These figures debunk the 40-year-old belief that the bed is the main site of allergen exposure," said chief investigator Associate Professor Euan Tovey.
"While specialist bedding probably offers some protection, it's elsewhere in the house, plus in offices and on public transport, that you really need to protect yourself."
House dust mites are the world's most common allergy-causing protein, with up to 1.2 billion people displaying some allergy to mites.
Exposure can cause symptoms like sneezing, asthma and red and watery eyes.
Research had previously shown mites were common in bed dust, leading experts to believe beds were the site of heaviest exposure.
However, with a small sample group of 10 people wearing the exposure sampling device for 20 days, as well as a camera that took photos every 15 seconds, Professor Tovey was able to better gauge exposure during different daily activities.
"We have long realised that most dust in houses and in clothing contains mite allergen," he said.
"But what we had not sufficiently taken into account is that dust needs to be dispersed into the air by movement before it can be inhaled.
"Generally you don't move much in your sleep and so exposure in beds is much less common than we thought - it was not until we actually measured airborne exposure through the day and night that the pattern of exposure became apparent."
Professor Tovey said the findings were useful, but made the issue of reducing exposure more complicated.
"Our suspicion is that allergen on clothing plays a much bigger role than previously thought, and while you can frequently wash some of your own clothing to reduce allergen, you are not going to be washing suits and jumpers each week, nor can you do that to all the other people on a bus."
Professor Tovey said the results explained why the majority of studies using specialist bed encasings alone had not been clinically effective.
"They did not sufficiently reduce total exposure," he said.
"It also means that whole-house approaches like air filtration, the better design of carpets and furnishings, and addressing other key exposure spots all need to be re-examined in light of their contributions to exposure."
The institute will now work towards further developing its prototype sampling device to help researchers measure other allergens and pollens.
