Newswise — Exposure to mold and dampness in homes as much as doubles the risk of asthma development in children, according to a study published today in the March issue of the peer-reviewed journal Environmental Health Perspectives (EHP). Researchers studied 1,984 Finnish children aged 1 to 7 years over a six-year period to see if they developed asthma. Data collection included a baseline survey administered in March 1991, as well as a follow-up survey in March 1997, asking questions about the child's health, parents' health, parent's highest education level, and details of the child's environment including exposure to environmental tobacco smoke and presence of feathery or furry pets.

The study focused particularly on four indicators or moisture or mold in the home, including mold odor, visible mold, visible moisture, and history of water damage. The presence of mold odor proved to be the only significant indicator of asthma development.

A a total of 138 children, or 7.2% of the study population, developed asthma during the study period. Having a parent with a history of allergies increased susceptibility in children. Mold odor increased the risk, the study found, independent of parents' medical histories. In fact, children living in homes with mold odor during the initial study period were more than twice as likely to develop asthma in the following 6 years. "These findings strengthen evidence that exposure to molds increases the risk of developing asthma in childhood," says lead author Jouni Jaakkola, director of the University of Birmingham's Institute for Occupational and Environmental Medicine. "They also show the importance of heredity—children of parents with asthma have a two-fold risk of asthma compared with children of nonasthmatic parents."

Children who were exposed to moisture or mold in the home were also slightly more likely to be exposed to environmental tobacco smoke, to have feathery or furry pets, and to have parents with a lower education level. The study adds to the body of evidence linking asthma with exposure to cigarette smoke.

"This study is important for families everywhere," says Dr. Jim Burkhart, science editor for EHP. "Anyone with young children in the home should be aware of the potentially harmful effects of long-term exposure to mold and this potential link to asthma in children."

In addition to Jaakkola, contributing authors included Bing-Fang Hwang of the Environmental Epidemiology Unit at the University of Helsinki in Finland, and Niina Jaakkola of the Department of Health Care Administration at Diwan College of Management in Taiwan. The article is available free of charge at

Funding sources for the research as reported by the authors included the Ministry of the Environment, the National Agency for Welfare and Health, the Medical Research Council of the Academy of Finland, and The Yrjö Jahnsson Foundation.

EHP is published by the National Institute of Environmental Health Sciences, part of the U.S. Department of Health and Human Services. EHP is an Open Access journal. More information is available online at

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Environmental Health Perspectives (Mar-2005)