Indoor environment in dwellings, asthma, allergies, and sick building syndrome in the Swedish population: a longitudinal cohort study from 1989 to 1997.

Objectives: To investigate changes of sick building syndrome (SBS) and different types of indoor exposures at home over an 8-year follow-up period (1989-1997), and onset of SBS symptoms in relation to size of residence town and education level.

Methods: A random sample (0.1%) of the population in a 3-county region in Sweden, initially aged 20-65 years (n = 466). In total, 348 (75%) answered the postal follow-up questionnaire.

Results: Water leakage during the last year had decreased from 11.2 to 4.8% visible indoor mould had decreased from 4.7 to 1.6%, and any sign of building dampness decreased from 16.1 to 9.5%. The prevalence of current smoking had decreased from 30 to 19%. Smokers at baseline reported more onset of SBS symptoms than non-smokers. Furthermore, remission from mucosal symptoms was less likely in subjects that were tobacco smoker. Subjects with any indoor painting during follow-up period reported more onset of SBS symptoms, and those with intermediate education level had more onset of skin symptoms.

Conclusion: Smoking and indoor painting could be predictors of new onset of SBS symptoms. Focus on indoor environment in Sweden the last decades may have resulted in environmental improvements in the dwellings, which can be beneficial both for the inhabitants and for the future public health.