Setting: Study of current asthma in adults in relation to the indoor environment.
Objectives: To assess the effect of building dampness in dwellings on the occurrence of current asthma, and biochemical signs of inflammation.
Design: A nested case-control study with 98 prevalent cases of asthma and 357 controls, within a stratified random population sample (20-45 years) from the Uppsala, Sweden, part of the European Community Respiratory Health Survey (ECRHS). Current asthma was defined as a combination of bronchial hyperresponsiveness and at least one asthma symptom (wheeze or attacks of breathlessness). Statistical calculations were made by multiple linear or logistic regression, adjusting for age, sex and smoking.
Results: Building dampness was found in 27% of dwellings. Current asthma was more common among subjects living in damp dwellings (odds ratio [OR] 1.8; 95% confidence interval [CI] 1.1-3.0), particularly with dampness in the floor construction (OR = 4.6; 95% CI 2.0-10.5). The average forced expiratory flow in one second (FEV1) was lower and peak expiratory flow (PEF) variability was higher in subjects from dwellings with floor dampness, and blood eosinophil count was increased in damp dwellings. No relation was found between immediate type allergy to house dust mites and current asthma or building dampness. Immediate type allergy to moulds (Cladosporium or Alternaria) was more prevalent in damp dwellings (9.3% vs 3.9%), and was related to current asthma (OR = 3.4; 95% CI 1.4-8.5).
Conclusions: Building dampness is common in dwellings in Sweden, and seems to be related to an increase in current asthma and biochemical signs of inflammation. Immediate type allergy to house dust mites does not seem to be the explanation, but immediate type allergy to moulds could explain some of the findings.