Long-term air pollution exposure is associated with increased severity of rhinitis in 2 European cohorts

Background: Very few studies have examined the association between long-term outdoor air pollution and rhinitis severity in adults. Objective: To assess the cross-sectional association between individual long-term exposure to air pollution and severity of rhinitis. Methods: Participants with rhinitis from two multicentre European cohorts (EGEA and ECRHS) were included. Annual exposure to NO2, PM10, PM2.5 and PMcoarse (calculated by subtracting PM2.5 from PM10) was estimated using land-use regression models derived from the ESCAPE project, at the participants’ residential address. The score of rhinitis severity (range 0-12), based on intensity of disturbance due to symptoms reported by questionnaire, was categorized in low (reference), mild, moderate and high severity. Polytomous logistic regression models with a random intercept for city were used. Results: 1408 adults with rhinitis (mean age: 52 years, 46% men, 81% from ECRHS) were included. The median [Q1-Q3] score of rhinitis severity was 4 [2-6]. Higher exposure to PM10 was associated with higher rhinitis severity (aOR[95% CI] for a 10 µg/m3 increase of PM10: for mild: 1.20[0.88-1.64], moderate: 1.53[1.07-2.19], and high severity: 1.72[1.23-2.41]). Similar results were found for PM2.5. Higher exposure to NO2 was associated with an increased severity of rhinitis, with similar aORs whatever the level of severity. aORs were higher among participants without allergic sensitization than in those with, but interaction was found only for NO2. Conclusions: People with rhinitis who live in areas with higher levels of pollution are more likely to report more severe nasal symptoms – further work is required to elucidate the mechanisms of this association.