Urban background particulate matter and allergic sensitization in adults of ECRHS II

Background: Epidemiological studies have shown weak or inconsistent associations between ambient air pollutants and allergic sensitization. The aim of this study was to evaluate whether regional urban air pollution may partly explain the large variation in the prevalence of allergic sensitization across cities of the European Community Respiratory Health Survey (ECRHS) II. Methods: ECRHS is a cross-sectional survey initiated in 29 countries across Europe in the 1990s (ECRHS I) with a follow-up conducted 10 years later (ECRHS II). Subject characteristics were measured by questionnaires and blood tests conducted for the measurement of specific immunoglobulin E. Fine particle mass (PM_2.5, <2.5 μm) and sulphur on PM_2.5 were measured in 21 centres and annual averages of urban regional background air pollution were calculated. Results were scaled by an interquartile range increase in ambient PM_2.5 (6.03 μg/m³) and sulphur (1336 ng/m³). Generalized estimating equations were applied to compute population average effect estimates with adjustment for age, gender, smoking habit, education and number of siblings. Results: A notable variation in pollution level and prevalence of allergic sensitization was observed. Moreover, exposure to urban regional background air pollution was not associated with allergic sensitization; adjusted odds ratios and 95% confidence interval were 1.02 (0.95-1.09) for PM_2.5 and 1.08 (0.86-1.31) for sulphur. These statistically non-significant associations were sensitive to model specification. Conclusions: The study suggests that regional air pollution measured at fixed sites is not associated with allergic sensitization among adults in ECRHS II.