Environmental exposure and sensitization patterns in a Swiss alpine pediatric cohort

BACKGROUND The level of environmental exposure throughout life may contribute to the prevalence of allergic sensitization and allergic disease. The alpine climate has been considered a healthy climate with little allergen exposure and pollution. We conducted a cross-sectional study to investigate local environmental exposure and concomitant prevalence of allergic sensitization among local school children born and raised in an alpine environment. METHODS Clinical and demographic data were collected with a questionnaire. Allergen content was assessed in residential settled dust samples, lifetime exposure to pollen and air pollution was calculated using data from national pollen and air pollution monitoring stations, and the allergic sensitization profile was determined with component resolved diagnostics (ISAC®). Univariate and multivariate regression models were used to estimate the relation between exposure and sensitization. RESULTS In a cohort of children born and raised in an alpine environment, sensitization to aeroallergens is quite common (38%), especially to grass (33%) and cat (16%). House dust mite allergen was detected in up to 38% of residential dust samples, but sensitization to HDM was low (2.5%). Pollutant levels were low, but an increasing trend was observed in the amount of ozone and PM$_{10}$. Living close to a busy road was associated with increased odds OR (95% CI) for being sensitized to any allergen 2.7 (1.0-7.2), to outdoor allergens 2.8 (1.1-7.1) and being sensitized plus reporting symptoms of rhinoconjunctivitis 4.4 (1.3-14.8) and asthma 5.5 (1.4-21). Indoor living conditions, including the presence of visible mold, increased the odds of being sensitized to indoor allergens (1.9 (1.1-3.2) and being sensitized plus reporting symptoms of rhinoconjunctivitis 1.9 (1.0-3.6) and asthma 2.1 (1.0-4.1). CONCLUSION In a healthy alpine environment, pollution might still be an important factor contributing to allergic sensitization.