(Ivanhoe Newswire) -- Children exposed to dust and other microbial agents early in life may be protected from developing asthma, according to new research. Microbials are small particles that can be inhaled.

Researchers from Utrecht University in the Netherlands and Massey University in Wellington, New Zealand, studied children's exposure to microbials at 3 months of age, then again at age 4.

During the four years of the study, researchers monitored the children's diagnosis of asthma and wheezing or the development of atopic sensitization, which can lead to allergies. They also measured dust on living room floors and infants' mattresses and serum IgE levels for common allergens. One group of participants was a given mite-impermeable mattress and pillow covers. A second group had a placebo of a cotton mattress and pillow covers.

Results show microbial levels in mattresses were low and were not associated with allergies or asthma. Levels of dust and other microbials on the floor, however, were linked to fewer cases of asthma by age 4. The group with the highest exposure had a lower risk of asthma and wheeze. Researchers say more studies are needed to understand the underlying mechanisms.

SOURCE: Journal of Allergy and Clinical Immunology, published online April 18, 2006