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Classroom airborne endotoxin levels lead to increased asthma symptoms

Inner-city children with asthma are at risk for experiencing more asthma symptoms because of being exposed to high airborne endotoxin levels at school, according to study results.

“Our study suggests that if classroom-specific airborne endotoxin levels are reduced from the average measured to the lowest measured levels, maximum asthma symptom days can be reduced by 1.4 days per two week period,” Peggy S. Lai, MD, of the department of pulmonary and critical care medicine at Massachusetts General Hospital, and colleagues wrote. “This translates to 34 fewer days per year of symptoms for each affected child, which is comparable to the effect seen with inhaled corticosteroids in the Childhood Asthma Management Program, and is approximately three times the effect size as that previously described for the addition of omalizumab to guideline-based asthma therapy in inner-city children.”

Lai and colleagues conducted a longitudinal cohort study of 248 students with asthma from 38 inner-city schools to determine if a link between classroom-specific dust and air endotoxin levels as well as home dust endotoxin levels existed.

The researchers identified school dust endotoxin levels (14.3 EU/mg) as being higher than home levels (11.2 EU/mg) (P = .02).

The researchers also noted 22% of classroom endotoxin levels exceeded 90 EU/m, a recommended occupational exposure limit for adults.

The researchers noted an association between classroom endotoxin levels with a dose-dependent increase in asthma symptom days for children with non-atopic asthma (aIRR = 1.16; 95% CI, 1.03-1.31).

The researchers noted limitations with the study, including how the researchers obtained air samples.

“Air sampling was performed with an ion-charging device due to the need for unobtrusive air sampling during classes,” the researchers wrote. “We did not make any direct comparisons of our sampling techniques against other sampling methods, although this method has previously been shown to yield results comparable to pump-based sampling methods.” – by Ryan McDonald

Disclosure: The researchers report no relevant financial disclosures.