Organic aerosol formation from 222 nm germicidal light: ozone-initiated vs. non-ozone pathways
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d4em00384e.pdf
Description
Published version
Size
1002.58 KB
Format
Adobe PDF
Checksum (MD5)
c1a2f2dba00cf505f8dae50dc770657b
Author(s)
Goss, Matthew B
Kroll, Jesse H
Date Issued
October 17, 2024
Journal
Environmental Science: Processes & Impacts
Publisher
Royal Society of Chemistry
Citation
Goss, Matthew B and Kroll, Jesse H. 2024. "Organic aerosol formation from 222 nm germicidal light: ozone-initiated vs. non-ozone pathways." Environmental Science: Processes & Impacts, 27 (6).
Version
Final published version
Abstract
Germicidal ultraviolet lamps outputting 222 nm light (GUV222) have the potential to reduce the airborne spread of disease through effective inactivation of pathogens, while remaining safe for direct human exposure. However, recent studies have identified these lamps as a source of ozone and other secondary pollutants such as secondary organic aerosol (SOA), and the health effects of these pollutants must be balanced against the benefits of pathogen inactivation. While ozone reactions are likely to account for much of this secondary indoor air pollution, 222 nm light may initiate additional non-ozone chemical processes, including the formation of other oxidants and direct photolytic reactions, which are not as well understood. This work examines the impacts of GUV222 on SOA formation and composition by comparing limonene oxidation under GUV222 and O3-only control conditions in a laboratory chamber. Differences between these experiments enable us to distinguish patterns in aerosol formation driven by ozone chemistry from those driven by other photolytic processes. These experiments also examine the influence of the addition of NO2 and nitrous acid (HONO), and investigate SOA formation in sampled outdoor air. SOA composition and yield vary only slightly with respect to GUV222vs. ozone-only conditions; NO2 and HONO photolysis do not appreciably affect the observed chemistry. In contrast, we observe consistent new particle formation under high-fluence 222 nm light (45 μW cm−2) that differs substantially from ozone-only experiments. This observed new particle formation represents an additional reason to keep GUV222 fluence rates to the lowest effective levels.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Massachusetts Institute of Technology. Department of Chemical Engineering
Terms of Use
Creative Commons Attribution-Noncommercial
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DOI of Published Version
https://doi.org/10.1039/D4EM00384E
