This article is a critical analysis of the following study: Zock JP, Jarvis D, Luczynska C, Sunyer J, Burney P; European Community Respiratory Health Survey. Housing characteristics, reported mold exposure, and asthma in the European Community Respiratory Health Survey. J Allergy Clin Immunol. 2002 Aug;110(2):285-92. The European Community Respiratory Health Survey (ECRHS), a multicenter study conducted in 18 countries during the 1990s, collected standardized information on the prevalence of asthma and the (known or suspected) risk factors for allergies and asthma. The relationships between damp housing, concentrations of viable fungal flora, dust mite allergens, and asthma have already been established in studies published on a country-by-country basis (Sweden, Germany, and Australia). No overall results had been published prior to those of the present study. The objective of the study is to investigate associations between housing characteristics (humidity, fungal contamination, and levels of house dust mite allergens) and adult asthma across all geographic regions of the ECRHS. The descriptive cross-sectional study by Zock et al. is a large-scale study with both strengths and limitations. The study population consists of a representative sample of young adults from several European and non-European countries. Health and environmental data were collected through interviews using a standardized questionnaire. The study also includes biological allergy measurements and respiratory function tests. Variables related to asthma are defined by a positive response to questions regarding respiratory symptoms over the previous 12 months. However, the diagnosis of asthma (current asthma) is not specifically based on a medical diagnosis but on reports of respiratory symptoms and/or medication use. There is no objective measurement of dust mites and mold in the indoor environment. However, specific allergen assays and a prick test were used as bioindicators. It would have been desirable for the authors to discuss the possible interaction between exposure to dust mites and exposure to mold. The documentation of a consistent risk of asthma across populations in different countries and a higher risk among individuals sensitized to mold lends plausibility to the results. Despite its limitations, this descriptive study represents an important milestone in the search for new knowledge regarding the link between indoor mold exposure and asthma. It justifies the need for further etiological studies using objective measures of exposure and focusing on potentially more vulnerable populations, such as children. (Excerpts from the article)