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

To assess the effects of radon exposure on asthma symptoms and lung function in school-aged children.Children, age 4 to 15 years, with persistent asthma who were already enrolled in the School Inner-City Asthma Study, which was a cohort study that had prospectively examined the effect of school classroom environmental exposures on asthma in children attending Northeast inner-city schools in the United States from 2008 to 2013.Baseline sociodemographic and medical history was based on questionnaires obtained before the start of the study. Subjects had either serum-specific IgE or allergy skin testing performed to assess allergic sensitization. Asthma symptoms were assessed by a phone survey every 3 months. Spirometry was done twice in the school year. Fractional exhaled nitric oxide (FeNO) was an outcome measure that was added in years 4 and 5 of the study and assessed in some of the subjects (n = 145). Residential radon exposure was measured using a spatiotemporal model that calculated the monthly indoor radon level (Bq/m3) for the Zip Code Tabulation Area, using the home zip code of the child within the greater Boston area. Weather season and allergic sensitization were assessed for any effects on the relationship between radon exposure and asthma. The monthly PM25, NO2, and O3 measurements were assessed for any potential confounding effects.All the subjects had documented radon exposure (n = 299). Subjects were mostly Black or Hispanic with household income < $25,000. Most (70%) had allergic sensitization and 30% were on inhaled steroid controller medication. The median indoor radon exposure was 49.75 Bq/m3, which is higher than the target radon level of 14.8 Bq/m3 set by the Indoor Radon Abatement Act of 1988 but lower than the EPA recommended action level of 148 Bq/m3 for indoor radon. Overall, higher radon exposure (>50th percentile radon) was associated with a greater change in FeNO from a warm to cold weather season (P = .0099), however radon exposure was not associated with any difference in spirometry outcomes. There was a statistically significant association between radon and an increase in maximum asthma symptom days. There was a generally a collinear correlation between the levels of radon and PM25, NO2, and O3, but there was generally no confounding by these other pollutants on radon’s effect. Weather season or allergic sensitization did not have any effect on the correlation between radon exposure and asthma symptom days or lung function.Children with higher radon exposure had more asthma symptoms and greater FeNO change from warm to cold weather seasons, suggesting that radon is an important environmental risk factor for airway inflammation and asthma symptoms.In recent years, some local municipalities, and even New York state, have banned the use of gas stoves in new buildings to reduce indoor pollutant exposures in the homes over concerns for possible environmental impacts and health risks, such as childhood asthma. Some of the limitations of this study are that residential radon levels were based on predictive models and not directly measured, and the confounding effects of other unmeasured copollutants are unknown. That said, results from studies like this could help inform scientists, environmental advocates, and lawmakers who are investigating environmental and climate change issues and could potentially impact governmental initiatives and future legislation.