Seasonal variations of size-classified aerosol-bound elements in school environments and risk factors for the prevalence of atopic diseases among pupils

Five-stage Sioutas impactors were used to collect particulate matter (PM) in 4 classrooms and the playground of a school with various educational levels near the largest industrial chemical complex in Portugal. Monitoring was carried out over a total period of 8 weeks split equally between winter and spring. Samples were analysed for its elemental composition by PIXE. The prevalence of respiratory symptoms in schoolchildren was assessed by applying the International Study of Asthma and Allergies in Childhood (ISAAC) standardised questionnaire. The mass concentration of quasi-ultrafine particles (PM0.25) was higher in winter, but lower than those reported in other studies. Elements accounted for 15.3–17.3 % and 25.6–34.1 % of the total PM10 mass in winter and spring, respectively. Elements such as K, S, Zn, Cu and Br presented a dominant mode in PM0.25, while Al, Mg, Ca, Fe and Si peaked at 2.5 μm. Throughout the campaign, Cl was the main component of the mass of PM greater than 0.5 μm in the schoolyard, while in classrooms Ca constituted the most abundant element of PM2.5-10. The results indicate that soil dust, cleaning products, biomass burning, traffic, the chemical complex and railway affected PM levels at the school. Taking paracetamol and living near roads with intense traffic of heavy vehicles were found to be statistically significant predictors of asthma symptoms, while the frequent consumption of antibiotics and children exposure to parental smoking during the first year of their life were found to increase the odds of developing symptoms of rhinitis.