Association Between Allergen Exposure in Inner-City Schools and Asthma Morbidity Among Students

Abstract

IMPORTANCE Home aeroallergen exposure is associated with increased asthma morbidity in children, yet little is known about the contribution of school aeroallergen exposures to such morbidity.OBJECTIVE To evaluate the effect of school-specific aeroallergen exposures on asthma morbidity among students, adjusting for home exposures. DESIGN, SETTING, AND PARTICIPANTSThe School Inner-City Asthma Study was a prospective cohort study evaluating 284 students aged 4 to 13 years with asthma who were enrolled from 37 inner-city elementary schools in the northeastern United States between March 1, 2008, and August 31, 2013. Enrolled students underwent baseline clinical evaluations before the school year started and were then observed clinically for 1 year. During that same school year, classroom and home dust samples linked to the students were collected and analyzed for common indoor aeroallergens. Associations between school aeroallergen exposure and asthma outcomes during the school year were assessed, adjusting for home exposures.EXPOSURES Indoor aeroallergens, including rat, mouse, cockroach, cat, dog, and dust mites, measured in dust samples collected from inner-city schools. MAIN OUTCOMES AND MEASURESThe primary outcome was maximum days in the past 2 weeks with asthma symptoms. Secondary outcomes included well-established markers of asthma morbidity, including asthma-associated health care use and lung function, measured by forced expiratory volume in 1 second. RESULTS Among 284 students (median age, 8 years [interquartile range, 6-9 years]; 148 boys and 136 girls), exposure to mouse allergen was detected in 441 (99.5%) of 443 school dust samples, cat allergen in 420 samples (94.8%), and dog allergen in 366 samples (82.6%). Levels of mouse allergen in schools were significantly higher than in students' homes (median settled dust level, 0.90 vs 0.14 μg/g; P < .001). Exposure to higher levels of mouse allergen in school (comparing 75th with 25th percentile) was associated with increased odds of having an asthma symptom day (odds ratio, 1.27; 95% CI, 1.05-1.54; P = .02) and 4.0 percentage points lower predicted forced expiratory volume in 1 second (95% CI, -6.6 to -1.5; P = .002). This effect was independent of allergic sensitization. None of the other indoor aeroallergens were associated with worsening asthma outcomes. CONCLUSIONS AND RELEVANCEIn this study of inner-city students with asthma, exposure to mouse allergen in schools was associated with increased asthma symptoms and decreased lung function. These findings demonstrate that the school environment is an important contributor to childhood asthma morbidity. Future school-based environmental interventions may be beneficial for this important public health problem.

The School Inner-City Asthma Intervention Study: Design, rationale, methods, and lessons learned

“…We first had to demonstrate that we were able to comprehensively understand the role of the school environment on asthma morbidity, adjusting for exposures in the home. [5] We then piloted in a school-based setting that we could feasibly bring down asthma-based triggers in schools. [16] This utilized classroom-suitable HEPA air filters[16] specifically adapted to maximize flow while minimizing noise.…”

“…[5,16,44–53] Our ongoing efforts are evaluating the additive role of the school environment, adjusting for home environment on health outcomes, and may provide additional support for school-based environmental intervention as a next step. The school may eventually be considered an effective target for asthma morbidity prevention.…”

“…The School Inner-City Asthma Study-1 (SICAS-1) (R01 AI 073964, Phipatanakul) was the first observational American study to comprehensively evaluate the role of urban exposures in school, classroom and home environments and asthma morbidity. [3,4] SICAS-1 showed that classroom-specific mouse allergen,[5] mold, and pollutant exposures are associated with asthma morbidity, adjusting for exposure in the home. [6–8] Until SICAS-1, most studies have focused on home exposures to allergenic and pollutant exposures and their associations with asthma morbidity.…”

Advances in environmental and occupational disorders in 2016

“…Finally, a study of inner-city schools discovered that increased exposures to mouse allergen in the schools was associated with increased asthma symptom days and decreased lung function. (74) A surprising finding of this study was that the association of mouse allergen exposure and asthma outcomes was significant irrespective of sensitization status. This indicates that high levels of mouse allergen exposure may be a direct irritant or result in non-allergic-mediated inflammation even in nonsensitized individual.…”

Bedroom Allergen Exposure Beyond House Dust Mites

“…While cockroach allergen exposure represents another important risk factor among these populations, mouse allergen may have greater clinical importance, at least in certain urban populations [53•]. Additionally, similar to the discussion above in regards to pet allergens, recent research has helped to elucidate inner-city schools as another critical site for exposure to mouse allergens among children, and such school-based exposure has been associated with both clinical and nonclinical measures of asthma severity [93]. …”