Association of indoor air pollution with rhinitis symptoms, atopy and nitric oxide levels in exhaled air.

BACKGROUND: Exposure to particulate matter (PM) outdoors can induce airway inflammation and exacerbation of asthma in adults. However, there is limited knowledge about the effects of exposure to indoor PM. The aim of this study was to investigate the association of exposure to indoor sources of PM with rhinitis symptoms, atopy and nitric oxide in exhaled air (FeNO) as a measure of airway inflammation. METHODS: We conducted a population-based cross-sectional study of 3,471 persons aged 18-69 years. Exposure to indoor sources of PM and prevalence of rhinitis symptoms were assessed by a self-administered questionnaire. Atopy was defined as at least 1 positive test (≥0.35 kU/l) for serum-specific IgE against grass, birch, cat or Dermatophagoides pteronyssinus. Regression analyses were used to adjust for confounders. RESULTS: Self-reported exposure to the use of woodstoves, candles or gas kitchen cookers was not significantly associated with either increased prevalence of rhinitis symptoms or atopy or increased levels of FeNO. The prevalence of atopy and allergic rhinitis and the levels of FeNO were significantly decreased among current and previous smokers. Exposure to environmental tobacco smoke (ETS) for 0.5-5 h, but not above 5 h, was significantly associated with a slightly increased prevalence of rhinitis symptoms. CONCLUSION: Self-reported exposure to the use of woodstoves, candles or gas cookers was not significantly associated with an increased risk of rhinitis symptoms or atopy, nor increased FeNO. Self-reported exposure to ETS was associated with a slightly higher prevalence of self-reported rhinitis symptoms without any clear dose-response relationship.