Current asthma and biochemical signs of inflammation in relation to building dampness in dwellings

SETTING: Study of current asthma in adults in relation to the indoor enviro nment. OBJECTIVES: To assess the effect of building dampness in dwellings on the o ccurrence of current asthma, and biochemical signs of inflammation. DESIGN: A nested case-control study with 98 prevalent cases of asthma and 3 57 controls, within a stratified random population sample (20-45 years) fro m the Uppsala, Sweden, part of the European Community Respiratory Health Su rvey (ECRHS). Current asthma was defined as a combination of bronchial hype rresponsiveness and at least one asthma symptom (wheeze or attacks of breat hlessness). Statistical calculations were made by multiple linear or logist ic regression, adjusting for age, sex and smoking. RESULTS: Building dampness was found in 27% of dwellings. Current asthma wa s 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 f loor construction (OR = 4.6; 95% CI 2.0-10.5). The average forced expirator y flow in one second (FEV1) was lower and peak expiratory flow (PEF) variab ility was higher in subjects from dwellings with floor dampness, and blood eosinophil count was increased in damp dwellings. No relation was found bet ween immediate type allergy to house dust mites and current asthma or build ing dampness. Immediate type allergy to moulds (Cladosporium or Alternaria) was more prevalent in damp dwellings (9.3% vs 3.9%), and was related to cu rrent 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 inf lammation. Immediate type allergy to house dust mites does not seem to be t he explanation, but immediate type allergy to moulds could explain some of the findings.