2016 No https://doi.org/10.1177/1420326X14562257 Su, Chunxiao North America Experimental Observational Exposure Study Students Elementary (K-5) Bacteria Fungi Absenteeism Bioaerosol Elementary schools Indoor air quality Upper room UVGI Bioaerosols and absenteeism were measured in 6 Midwestern US classrooms with and without upper-room UVGI. Sampling close to occupied periods showed UVGI reduced culturable bacteria but not absenteeism. Results support time-sensitive evaluation of interventions.