Airborne allergens, endotoxins, and particulate matter in elementary schools, results from Germany (LUPE 2)

Allergic disorders are the most common childhood-related chronic diseases in developed countries. It is essential to assess the exposure, especially in schools, where children spend a large portion of their time. We aimed to investigate allergen and endotoxin levels in the air of schools and to observe seasonal variations of these factors. We evaluated airborne concentrations of house dust mites allergens (Der p 1, Der f 1), cat allergen (Fel d 1), and endotoxin in PM10 in 14 classrooms during the school days in the region of Munich, each over 20 consecutive days and in 1 classroom over the course of a year (at 83 days); we also tested outdoor air close to the schools. Endotoxin levels were quantified using two different analytical methods. In addition, indoor air climate parameters were measured. The median daily indoor CO2 and PM10 concentrations in the classrooms ranged from 423 to 3,135 ppm (median: 1,211 ppm) and 9 to 390 μg/m(3) (median: 127 μg/m(3)), respectively. Fel d 1 in the PM10 samples was the most frequently detected allergen, with levels from 0.02 to 1.15 ng/m(3) in a total of 301 samples (median: 0.19 ng/m(3), 95th percentile: 0.57 ng/m(3)). Der p 1 and Der f 1 were detected in only 51% and 19% of the samples, with 95th percentiles at 0.5 and 0.3 ng/m(3). Endotoxin levels in the PM10 and inhalable dust samples ranged from 0.5 to 84.1 EU/m(3) (median: 15.3 EU/m(3); 95th percentile: 58.2 EU/m(3)) and from 0.03 to 115 EU/m(3) (median: 8.4 EU/m(3); 95th percentile: 27.9 EU/m(3)). Fel d 1 and endotoxin were found in higher levels in the winter months. The results of the two different indoor sampling techniques for endotoxin were statistically significantly correlated. The results of airborne allergens indicate a generally low exposure level in classrooms. With regard to endotoxin, our study showed higher levels in schools compared with residences.