Effect of Radon Exposure on Asthma Morbidity in the School Inner-City Asthma Study

Background: Radon may have a role in obstructive lung disease outside its known carcinogenicity. Little is known about radon’s effects on asthma morbidity. Objective: To determine the effect of radon on fractional exhaled nitric oxide (F NO), asthma symptom-days, and lung function in inner-city asthmatic school-children. Methods: Two hundred ninety-nine school-aged asthmatic children enrolled in the School Inner-City Asthma Study (SICAS-1) were followed. One and two-month averaged radon was assessed using a spatiotemporal model predicting zip code-specific monthly exposures. F NO and spirometry were measured twice during the academic year. Asthma symptoms were assessed four times during the academic year. The interaction between indoor radon exposure (Bq/m ) and seasonality predicting log-transformed F NO, FEV % predicted, FVC% predicted, FEV /FVC, and asthma symptom-days was evaluated. Results: : Participants with high radon exposure had greater change in F NO from warm to cold periods compared to low radon exposure (interaction p=0.0013). Participants with >50 percentile radon exposure experience significant F NO increase from warm to cold weather ( β =0.29 [95% CI: 0.04,0.54], p=0.0240). We report a positive association between radon 1-month moving average (IRR=1.01, p=0.0273) and 2-month moving average (IRR=1.01, p=0.0286) with maximum asthma symptom-days (n=299, obs=1,167). Conclusions: : In asthmatic children, radon may be associated with increased asthma morbidity, suggesting radon may be a modifiable environmental risk factor for airway inflammation.