Mukharesh et al . Page 2
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Based on the mechanism of airway injury and recent findings in COPD , we hypothesized that radon exposure would be associated with asthma diagnosis and asthma symptoms in children .
2 | MATERIALS AND METHODS
3 | RESULTS
This was a cross-sectional study utilizing screening survey data from three prospective National Institutes of Health / National Institute of Allergy and Infectious Diseases-funded elementary school-based clinical studies ; School Inner-City Asthma Study ; SICAS-1 ( n = 1358 ), which was conducted between 2008 and 2013 , SICAS-2 pilot ( n = 44 ), from 2013 to 2014 , and SICAS-2 ( n = 1862 ), which was conducted between 2015 and 2020 . These studies were broadly aimed to assess the effect of the indoor environment on asthma morbidity in school-age children with asthma . For each of these studies , parents of children in Northeastern United States elementary schools completed a brief screening questionnaire regarding asthma diagnosis and specific asthma symptoms . Surveys were distributed in school classrooms to all children to be completed by their caregiver and collected by the study team upon return . Additional details regarding the methods have been published previously . 6 , 7
For the current analysis , the primary outcome , asthma diagnosis , was determined by answering “ yes ” to a physician diagnosis of asthma and / or current use of a medication for asthma on a study population screening eligibility form . Secondary outcomes included report of symptoms of wheezing , nighttime difficulty breathing , nocturnal cough , and missed school days . The answers were dichotomized to “ never ” versus “ sometimes ” or “ a lot .”
Estimates of monthly radon concentrations were calculated for each participant ’ s school ZIP Code Tabulation Area in the region from 2005 to 2018 through a two-stage machine learning model that has been published previously . 8 Moving averages were calculated for 1 , 5 , 7 , 12 , and 24 months of exposure before the outcome assessment .
A logistic regression model was used to evaluate the association of asthma and symptoms with ground radon exposure ( pCi / L ) adjusting for age , race , cohort , and year of assessment .
There were 3264 respondents to the screening survey with complete school exposure data that were included in the analysis . The mean age of the participants was 8 years ( range 3 to 15 years ), 27 % self-identified as Black , 22 % as White , 7 % as Mixed , and 44 % identified as Other race . The prevalence of asthma was 25 %. Reported respiratory symptoms of nocturnal coughing was 36 %, wheezing was 29 %, nighttime difficulty breathing was 14 %, and missed school days was 13 %. Ranges of radon monthly estimates ( pCi / L ) in the school environment are shown in Table 1 . Logistic regression analysis demonstrated a significant association between short-term ( 1 , 5 , and 7 months ) radon exposure and asthma diagnosis as well as short- and long-term ( 12 and 24 months ) radon exposure and having twice the odds of school absences ( p < 0.05 ). The effect of short- and long-term radon
Pediatr Pulmonol . Author manuscript ; available in PMC 2022 December 01 .