Background: A large number of epidemiological studies have shown that parental atopy and the presence of home dampness and molds are associated with asthma-like symptoms. Methods: Two cross-sectional surveys (1994/1995 and 1999/2000) were conducted, using data from the International Study of Asthma and Allergies in Childhood (ISAAC) phase I and III surveys, collected in Münster, Germany (n = 6,996; response proportion 81.8%). Outcomes of interest were the prevalence of wheeze during the last twelve months, sleep disturbance because of wheeze, wheeze after exercise, and current asthma in six- to seven-year-old children. Exposure was assessed with a question regarding a history of atopy in either parent and with a question regarding the presence of dampness or visible molds in the child's bedroom. Risk estimates were calculated as prevalence ratios (PR) with 95% confidence intervals (CI), adjusting for several potential confounders. Results: Comparing the PR in four exposure categories, an excess risk of asthma-related outcomes was observed when joint effects of mold exposure and a positive family history of atopy were assessed, e. g., for wheeze after exercise (PR 1.97, 95% CI 1.61-2.41, in children with parental atopy, but without mold exposure; PR 1.25, 95% CI 0.71-2.20, in mold-exposed children without a history of parental atopy; PR 2.60, 95% CI 1.58-4.34, in children with both factors). Conclusion: Parental atopy and exposure to molds did not have independent effects on the outcomes under observation.
