Disinfection Byproduct Formation via Multiphase Hypochlorous Acid Chemistry

DOUGLAS COLLINS, Christopher Azzam, Risa Kanefsky, Bucknell University

     Abstract Number: 410
     Working Group: Indoor Aerosols

Abstract
The expansion of enhanced disinfection measures associated with the emerging understanding of airborne pathogens is currently leading to the proliferation of technologies to clean air and indoor spaces. Hypochlorous acid (HOCl) has been applied as a disinfectant via fogging but also can be released into the gas phase in substantial quantities during the use of chlorine bleach (sodium hypochlorite) solutions. HOCl is a potent oxidizer that reacts with a broad spectrum of chemical functional groups, lending to its strong disinfecting action. Prior studies have demonstrated that HOCl is removed from indoor air faster than the air exchange rate, and also demonstrated its multiphase reactivity with olefins and certain components known to exist in biomass burning particles. In the present study, we investigate the role of HOCl reactivity with catechol and methoxyphenols in the direct formation of hydroxylated polychlorinated biphenyls (OH-PCBs) and related compounds. It should be noted that OH-PCBs are known metabolites and oxidation products of PCBs and are thought to be of similar toxicity. Using liquid chromatography and advanced mass spectrometry, we demonstrate de novo formation of OH-PCBs upon uptake of gaseous HOCl to phenolic compounds applied to glass surfaces. Phenolic compounds are abundant in biomass burning aerosol, which is an increasingly important component of PM2.5 in populated environments in association with increasingly frequent wildfires. Hence the use of chlorine bleach or HOCl-based disinfectants in wildfire smoke-affected buildings could lead to the formation of toxic byproducts.