Dust could protect children from asthma - research

Exposing children early in life to dust and other microbial agents could protect them from developing asthma, according to a Massey University academic.

Massey epidemiologist Associate Professor Jeroen Douwes said he has tracked 700 Dutch children since before birth and found that the more children are exposed to dust, dirt and microbials, such as bacteria and fungi, as well as pets and farm animals, the greater the odds they will not develop asthma.

"The children who were highly exposed to microbials were 60 per cent less likely to develop asthma in the first four years of life," said Dr Douwes.

The research may bolster the "hygiene hypothesis," which says one reason asthma is rising is that young children no longer come into contact with as many of the germs that arm a maturing immune system against certain allergic conditions.

One in four New Zealand children is affected by respiratory disease, says the Asthma and Respiratory Foundation.

New Zealand has one of the highest rates of respiratory disease in the developed world, with asthma estimated to cost the country $825 million a year

In the Dutch research, the children were watched for the development of asthma symptoms such as wheezing or "atopic sensitisation" which can develop into allergies and may be inherited from one of their parents.

If a child develops this allergy the reaction is instant when coming into contact with the allergen.

Dr Douwes says the researchers measured the amount of dust found in the children's living room floors and on their mattresses.

"We compared the use of mite-impermeable mattress and pillow covers with a control group using a regular cotton mattress and pillow cases," he said . The study also assessed whether children had allergies, by measuring antibodies in their blood.

"Different beddings did not seem to be significant. The measurements between the mite-impermeable and regular bedding was not much different. It did not seem to affect the levels of children developing asthma."

What did make the difference in whether the children developed asthma was how clean the living room floor was.

The children that were the most exposed to microbials on the floor had a lower risk for developing asthma or a wheeze. "This longitudinal study is strong evidence that removing carpets and pets in an effort to reduce the risk of children developing asthma is not effective," said Prof Douwes. "It may make things worse".

But if a child had developed asthma as a reaction to indoor allergens, removing carpets and pets was likely to help.

- NZPA