BackgroundAsthma management involves medications with environmental control, but patient adherence to the latter is poor. A previous pilot study found an ultraviolet indoor air-irradiation system (CREON2000A) was effective in reducing asthma severity in children with mild to moderate asthma.ObjectiveThis trial's purpose was to confirm these results in a larger population over a longer time duration.MethodsA 12-month randomized, sham device-controlled multicenter study enrolled 79 children with mild to moderate persistent asthma aged 6 to <18 years. Participants were randomized to have a CREON2000A ultraviolet air irradiation device or a sham device installed in their home's ventilation system. Enrolled children were assessed with the Composite Asthma Severity Index at baseline and every 4 months; asthma treatment was adjusted according to National Heart, Lung, and Blood Institute EPR-3 guidelines. The primary analysis compared the efficacy of the CREON2000A versus sham device from baseline to end of study (12-month visit). A sensitivity analysis compared efficacy across the 4-, 8-, and 12-month visits.Trial registrationInvestigate the Effect of the CREON2000A on Asthma Control in Children With Mild to Moderate Persistent Asthma (CREON2000A), ClinicalTrials.gov, NCT02715375.ResultsBaseline demographic characteristics of CREON2000A (n = 40) versus sham device (n = 39) groups were similar. The primary analysis estimated a difference in Composite Asthma Severity Index score for CREON2000A at 12 months relative to the sham device, which was not statistically significant (ΔEstimated = 0.53; P = .404; 95% confidence interval, -0.576, 1.628). A sensitivity analysis detected a device benefit across all postbaseline values (ΔEstimated = 0.76; P = .034; 95% confidence interval, 0.057, 1.465). A benefit was also observed for asthma daytime symptom score, average asthma exacerbations score, missed school days, rhinitis symptoms, and average number of respiratory infections (nominal P < .05 in all cases).ConclusionThis small trial is inconclusive, but some results show promise, suggesting that this device and the concept of indoor air irradiation as an environmental intervention is worthy of further study in children with mild to moderate persistent asthma.