Ceiling impact on air disinfection performance of Upper-Room Germicidal Ultraviolet (UR-GUV)

Shengwei Zhu; Tong Lin; Lingzhe Wang; Edward A Nardell; Richard L Vincent; Jelena Srebric

doi:10.1016/j.buildenv.2022.109530

Ceiling impact on air disinfection performance of Upper-Room Germicidal Ultraviolet (UR-GUV)

Build Environ. 2022 Oct:224:109530. doi: 10.1016/j.buildenv.2022.109530. Epub 2022 Aug 31.

Authors

Shengwei Zhu¹, Tong Lin¹, Lingzhe Wang¹, Edward A Nardell², Richard L Vincent³, Jelena Srebric¹

Affiliations

¹ Department of Mechanical Engineering, University of Maryland, College Park, MD, USA.
² Departments of Environmental Health and Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
³ Icahn School of Medicine Mount Sinai, New York City, NY, USA.

Abstract

This study used Computational Fluid Dynamics (CFD) to investigate air disinfection for SARS-CoV-2 by the Upper-Room Germicidal Ultraviolet (UR-GUV), with focus on ceiling impact. The study includes three indoor settings, i.e., low (airport bus), medium (classroom) and high (rehearsal room) ceilings, which were ventilated with 100% clean air (CA case), 80% air-recirculation with a low filtration (LF case), and 80% air-recirculation with a high filtration (HF case). According to the results, using UR-GUV can offset the increased infection risk caused by air recirculation, with viral concentrations in near field (NF) and far field (FF) in the LF case similar to those in the CA case. In the CA case, fraction remaining (FR) was 0.48-0.73 with 25% occupancy rate (OR) and 0.49-0.91 with 45% OR in the bus, 0.41 in NF and 0.11 in FF in the classroom, and 0.18 in NF and 0.09 in FF in the rehearsal room. Obviously, UR-GUV performance in NF can be improved in a room with a high ceiling where FR has a power relationship with UV zone height. As using UR-GUV can only extend the exposure time to get infection risk of 1% (T _1% ) to 8 min in NF in the classroom, and 47 min in NF in the rehearsal room, it is necessary to abide by social distancing in the two rooms. In addition, T _1% in FF was calculated to be 18.3 min with 25% OR and 21.4% with 45% OR in the airport bus, showing the necessity to further wear a mask.

Keywords: Airborne infection; COVID-19; Ceiling height; Computational Fluid Dynamics (CFD); Filtration; Upper-Room Germicidal Ultraviolet (UR-GUV).