Researchers found that of nearly 1,900 Finnish children they followed for six years, those who lived in homes with dampness or mold problems were more likely to develop allergic rhinitis during the study period.

Allergic rhinitis refers to symptoms of congestion, sneezing and runny nose caused by allergens such as pollen, dust, animal dander or mold.

In this study, published in the American Journal of Epidemiology, 16 percent of children whose parents reported dampness in the home went on to be diagnosed with allergic rhinitis over the next six years. That compared with just under 12 percent of children whose parents reported no dampness problems -- that is, no visible signs of water damage to the ceilings, walls or floors, and no visible mold or mold odor in the home.

The researchers weighed a number of factors that might help account for the connection, including families' socioeconomic status (asthma and allergies tend to be common in lower income children) and whether children were also exposed to second-hand smoke.

However, damp, moldy conditions in the home remained linked to an increased risk of children's nasal allergies. Children whose parents reported any mold or water damage in the home at the outset were 55 percent more likely than other children to develop allergic rhinitis -- connected to any allergen, and not just mold.

Our study strengthens the evidence that exposure to indoor dampness increases the risk of developing allergic rhinitis, lead researcher Dr. Jouni Jaakkola, of the Institute of Health Sciences in Oulu, Finland, told Reuters Health in an email.

Previous studies, he said, had measured children's exposure to dampness and mold, and their rates of nasal allergies, all at one time -- making it impossible to tell whether the exposure preceded the allergies' development.

The fact that this study followed children's rates of allergy development over time strengthens the case that household dampness is a risk factor for nasal allergies -- though the findings alone do not prove cause-and-effect. It is still possible that there are other factors that explain the link.

However, Jaakkola said that based on other research, it is plausible that damp conditions in the house contribute to nasal allergies. Such conditions, he noted, encourage the growth of dust mites and fungi, and attract cockroaches -- all of which can serve as allergy triggers. Moisture may also boost the emission of chemicals from building materials, according to Jaakkola, and those chemicals could potentially create inflammation in the airways.

The bottom line for parents, Jaakkola said, is that they would be wise to look out for signs of water damage at home.

In general, we should try to avoid dampness problems in homes and repair (damage) as soon as the problems appear, he noted, adding that parents of children who already have any form of allergy should be particularly careful to do so.

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