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

Very few studies have examined the association between long-term outdoor air pollution and rhinitis severity in adults.

We sought to assess the cross-sectional association between individual long-term exposure to air pollution and severity of rhinitis.

Participants with rhinitis from 2 multicenter European cohorts (Epidemiological Study on the Genetics and Environment on Asthma and the European Community Respiratory Health Survey) were included. Annual exposure to NO₂, PM₁₀, PM_2.5, and PM_coarse (calculated by subtracting PM_2.5 from PM₁₀) was estimated using land-use regression models derived from the European Study of Cohorts for Air Pollution Effects 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 into low (reference), mild, moderate, and high severity. Polytomous logistic regression models with a random intercept for city were used.

A total of 1408 adults with rhinitis (mean age, 52 years; 46% men, 81% from the European Community Respiratory Health Survey) were included. The median (1st quartile-3rd quartile) score of rhinitis severity was 4 (2-6). Higher exposure to PM₁₀ was associated with higher rhinitis severity (adjusted odds ratio [95% CI] for a 10 microg/m³ increase in 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 PM_2.5. Higher exposure to NO₂ was associated with an increased severity of rhinitis, with similar adjusted odds ratios whatever the level of severity. Adjusted odds ratios were higher among participants without allergic sensitization than among those with, but interaction was found only for NO_2. 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.