Background and Objective:
Schools are potential settings for student exposure to environmental asthma triggers, but the health impact of such exposures is undetermined. This study quantified levels of indoor allergens, particulate matter (PM2.5), ventilation, and indoor climate factors in western Washington State elementary schools. Relationships between the most prevalent environmental exposures and short-term changes in airway inflammation in children with asthma were investigated.
Forty-five children with non-steroid-treated asthma from 42 schools across 9 public school districts participated. Offline fractional exhaled nitric oxide (FENO), a biomarker of airway inflammation, was measured in breath collected from each participant at home on a weekend and subsequently twice at school (morning and afternoon). During the school visits, floor dust was vacuum sampled and PM2.5, carbon dioxide (CO2), temperature, and relative humidity were measured in each child’s primary classroom. Cat, dog, mouse, rat, three dust mite, and two cockroach allergens were measured in the dust with antibody-based ELISAs. Multivariate linear regression models analyzing the environmental exposure-school afternoon FENO associations controlled for home or school morning FENO.
Classrooms frequently had inadequate ventilation (82% with peak CO2 >1,000 ppm). School-day average PM2.5 ranged from 6 to 41 μg/m3. Dog, cat, and mouse allergens were detectable in most classrooms (93%–100%), while the three dust mite allergens were detectable at varying frequencies (18%–70%). Increasing allergen or PM2.5 concentrations were not significantly associated with within-child increases in FENO over the school day or between the weekend home and afternoon school day breath collections.
Indoor asthma triggers at the concentrations measured in these WA classrooms were not significantly associated with short-term inflammatory effects in participating children with asthma. Research into health impacts of children’s environmental exposures in different settings, including schools, should help target asthma trigger-reduction efforts.