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Photolysis-driven indoor air chemistry following cleaning of hospital wards.

Authors :
Wang Z
Kowal SF
Carslaw N
Kahan TF
Source :
Indoor air [Indoor Air] 2020 Nov; Vol. 30 (6), pp. 1241-1255. Date of Electronic Publication: 2020 Jun 28.
Publication Year :
2020

Abstract

Effective cleaning techniques are essential for the sterilization of rooms in hospitals and industry. No-touch devices (NTDs) that use fumigants such as hydrogen peroxide (H <subscript>2</subscript> O <subscript>2</subscript> ), formaldehyde (HCHO), ozone (O <subscript>3</subscript> ), and chlorine dioxide (OClO) are a recent innovation. This paper reports a previously unconsidered potential consequence of such cleaning technologies: the photochemical formation of high concentrations of hydroxyl radicals (OH), hydroperoxy radicals (HO <subscript>2</subscript> ), organic peroxy radicals (RO <subscript>2</subscript> ), and chlorine radicals (Cl) which can form harmful reaction products when exposed to chemicals commonly found in indoor air. This risk was evaluated by calculating radical production rates and concentrations based on measured indoor photon fluxes and typical fumigant concentrations during and after cleaning events. Sunlight and fluorescent tubes without covers initiated photolysis of all fumigants, and plastic-covered fluorescent tubes initiated photolysis of only some fumigants. Radical formation was often dominated by photolysis of fumigants during and after decontamination processes. Radical concentrations were predicted to be orders of magnitude greater than background levels during and immediately following cleaning events with each fumigant under one or more illumination condition. Maximum predicted radical concentrations (1.3 × 10 <superscript>7</superscript> molecule cm <superscript>-3</superscript> OH, 2.4 ppb HO <subscript>2</subscript> , 6.8 ppb RO <subscript>2</subscript> and 2.2 × 10 <superscript>8</superscript> molecule cm <superscript>-3</superscript> Cl) were much higher than baseline concentrations. Maximum OH concentrations occurred with O <subscript>3</subscript> photolysis, HO <subscript>2</subscript> with HCHO photolysis, and RO <subscript>2</subscript> and Cl with OClO photolysis. Elevated concentrations may persist for hours after NTD use, depending on the air change rate and air composition. Products from reactions involving radicals could significantly decrease air quality when disinfectants are used, leading to adverse health effects for occupants.<br /> (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Details

Language :
English
ISSN :
1600-0668
Volume :
30
Issue :
6
Database :
MEDLINE
Journal :
Indoor air
Publication Type :
Academic Journal
Accession number :
32485006
Full Text :
https://doi.org/10.1111/ina.12702