Health Impacts of GUV222-Generated Pollution under Low Ventilation May Be Its Most Important Limitation
JOSE-LUIS JIMENEZ, Joost de Gouw, Daven Henze, Zhe Peng,
University of Colorado, Boulder Abstract Number: 388
Working Group: Aerosol Science of Infectious Diseases: Lessons and Open Questions on Models, Transmission and Mitigation
AbstractGermicidal ultraviolet disinfection at 254nm (GUV254) has been used for a century, with its perceived main limitation being careful installation to avoid skin/eye irradiation. GUV222 has received intense recent attention, due to much reduced skin/eye impacts. However, both wavelengths produce indoor air pollution, which had not been examined in detail.
Although it has been known that some O
3 is generated by GUV222, its importance is ~10,000 higher than previously thought. This is a combination of (a) an O
3 generation rate ~100 times larger than in a recent review (Claus, 2021) and (b) the incorrect assumptions that only O
3 itself was a concern; that any O
3 lost indoors is of no consequence; and that any remaining O
3 below threshold limit values of 50-100 ppb has negligible health impacts; (c) the fact that O
3 and radicals generated from it (OH, NO
3) combine with very abundant indoor volatile organic compounds (VOCs) to produce indoor PM, a pollutant ~50 times more deadly than O
3 itself on a mass basis. Additional risks due to oxidized VOCs, ultrafine particles, and possibly unknown unknowns remain to be characterized.
Application to a simple case study shows that GUV222 at the ACGIH limit under low ventilation may result in as many deaths from indoor pollution as the lives saved from reducing infection. Very low fluence rates may still have significant germicidal properties (if viral disinfection results from Welch et al. 2021 hold in the real world), and may allow the use of GUV222 even under low ventilation. GUV254 results in less pollution formation under low ventilation. Ventilation reduces GUV222 pollution quadratically, as O
3, VOC, and PM are all diluted. Filtration reduces PM, while activated carbon can reduce O
3 and VOC. Health benefits vs. harms of GUV222 are explored vs. average fluence rate and ventilation / filtration rates.