Indoor Environmental Factors and its Associations with Asthma and Allergy Among Swedish Pre-School Children

Abstract: It has been shown in a large number of scientific studies that living or working in a building with mould and moisture damage increases the risk for asthmatic and allergic symptoms. However, there is a need to establish more valid methods to obtain a more nuanced picture of the wide range of different types of moisture related problems. Furthermore, the causal relationships and the biological mechanisms between moisture damage and health have to be shown. The study Dampness in Buildings and Health (DBH) was started in the year 2000. Results from the first two phases of the study (a cross sectional questionnaire study on 10,851 children and a nested case control study on 198+202 children) are included in the thesis The overall aim of this work has been to study the impact of moisture related problems in homes on asthmatic and allergic diseases among children. A dose response relationship was observed, in the case control study, between doctor diagnosed asthma/allergy among the children and inspectors perception of a mouldy odour along the skirting board i.e. a probably sign of hidden mould damage inside the building structure. Inspectors observations of visible damp stains or mould odour in a room were not associated with studied health effects. The ventilation rate in more than 80% of the single family houses and around 60% of the multi family houses did not fulfil the Swedish building code requirement. It was found that children with asthma and allergy more often lived in homes with a low ventilation rate and a dose response relationship was indicated for this association in single family houses. Validation of the used questionnaire showed that parental reports were in good agreement with the inspectors observations regarding building characteristics, such as type of house and type of foundation and to a lower degree for type of ventilation system and flooring material. However, the concordance for mould odour and visible signs of dampness was poor. Day care attendance was shown to increase the risk for infectious diseases e.g. common colds, as expected, but also for asthmatic and allergic symptoms among children. In conclusion, 'dampness' in buildings is a major risk factor for health effects among children, such as asthma and allergies. Parental questionnaire reports on 'dampness' were more valid from a health point of view than observations from inspectors.