2017 Yes https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5295302/ Su, Chunxiao North America Observational Elementary (K-5) Ultraviolet germicidal irradiation School Indoor air quality Real-time detection Fluorescent bioaerosol The classroom with upper-room UVGI showed significantly lower concentrations of fine size (<3 μm) and total FBCs than the control classroom during 13 of the 20 visiting days.