Current wheeze,asthma, respiratory infections,and rhinitis among adults in relation to inspection data and indoor measurements in single‐family houses in Sweden—The BETSI study

In the Swedish Building Energy, Technical Status and Indoor environment study, a total of 1160 adults from 605 single‐family houses answered a questionnaire on respiratory health. Building inspectors investigated the homes and measured temperature, air humidity, air exchange rate, and wood moisture content (in attic and crawl space). Moisture load was calculated as the difference between indoor and outdoor absolute humidity. Totally, 7.3% were smokers, 8.7% had doctor’ diagnosed asthma, 11.2% current wheeze, and 9.5% current asthma symptoms. Totally, 50.3% had respiratory infections and 26.0% rhinitis. The mean air exchange rate was 0.36/h, and the mean moisture load 1.70 g/m³. Damp foundation (OR=1.79, 95% CI 1.16‐2.78) was positively associated while floor constructions with crawl space (OR=0.49, 95% CI 0.29‐0.84) was negatively associated with wheeze. Concrete slabs with overlying insulation (OR=2.21, 95% CI 1.24‐3.92) and brick façade (OR=1.71, 95% CI 1.07‐2.73) were associated with rhinitis. Moisture load was associated with respiratory infections (OR=1.21 per 1 g/m³, 95% CI 1.04‐1.40) and rhinitis (OR=1.36 per 1 g/m³, 95% CI 1.02‐1.83). Air exchange rate was associated with current asthma symptoms (OR=0.85 per 0.1/h, 95% CI 0.73‐0.99). Living in homes with damp foundation, concrete slabs with overlying insulation, brick façade, low ventilation flow, and high moisture load are risk factors for asthma, rhinitis, and respiratory infections.