Effects of Germicidal Far-UVC on Indoor Air Quality in an Office Setting

ZIFENG TANG, Farideh Hosseini Narouei, Shiqi Ian Wang, Raabia Hashmi, Sandhya Sethuraman, David Welch, David Brenner, V. Faye McNeill, Columbia University

     Abstract Number: 155
     Working Group: Indoor Aerosols

Abstract
The application of 222 nm light from KrCl excimer lamps (GUV222 or Far-UVC) is a promising approach to reduce the indoor transmission of airborne pathogens, including the SARS-CoV-2 virus. GUV222 inactivates airborne pathogens and is believed to be relatively safe for human skin and eye exposure. However, UV light initiates photochemical reactions which may negatively impact indoor air quality. We conducted a series of experiments to assess the formation of ozone (O3) and secondary organic aerosols (SOA) induced by commercial GUV222 devices in an office environment. We find that a single GUV222 lamp (room average 0.29 mW cm^-2, 1.65 mW cm^-2 at sampling location) does not significantly impact O₃ or fine particulate matter levels. Higher GUV222 fluence (room average 1.16 mW cm-2) leads to increases in O₃ up to 10 ppb above background, and minor increases in particulate matter. The use of GUV222 at low intensities and in conjunction with adequate ventilation may reduce airborne pathogen levels while minimizing the formation of air pollutants.