Abstract View
Oxidized Primary Organic Aerosol and Secondary Organic Aerosol Formation Initiated by Chlorine Oxidation of Indoor Pollutants during Bleach Cleaning
ANITA AVERY, Francesca Majluf, Jordan Krechmer, Nirvan Bhattacharyya, Lea Hildebrandt Ruiz, Maddy Reed, William Brune, Manjula Canagaratna, Andrew Lambe, Aerodyne Research, Inc.
Abstract Number: 523
Working Group: Indoor Aerosols
Abstract
Bleach cleaning activities, which are becoming increasingly prevalent in response to the SARS-CoV-2 pandemic, emit reactive halogen species, including molecular chlorine (Cl2) and hypochlorous acid (HOCl), that participate in complex, multiphase chemistry. These chlorinated compounds are detrimental to human health. Additionally, reactions between indoor air pollutants (IAPs) and chlorine atoms (Cl) plus hydroxyl radicals (OH) that are generated from photolysis of Cl2 and/or HOCl generate oxidized primary organic aerosol (OPOA) and/or secondary organic aerosol (SOA) species, which are also associated with adverse health effects. However, the mechanisms leading to OPOA and SOA formation during bleach cleaning are poorly understood. To investigate SOA/OPOA generated during indoor bleach cleaning activities, a prototype halogen oxidation flow reactor (OFR) equipped with low-pressure mercury lamps (λ= 254 or λ > 350 nm emission output) was developed. The halogen OFR can generate elevated OH and Cl concentrations that are available for reaction with surrogate IAPs in several minutes’ exposure time. In different experiments, the oxidants employed were switched between Cl, Cl + OH, HOCl and Cl2 by varying the precursor halogen species and the OFR photochemical conditions. α-pinene, squalene, and oleic acid (representative of passive indoor, human, and cooking sources, respectively) were used as SOA/OPOA precursors. SOA/OPOA generated from these reactions were characterized with several state-of-the-art mass spectrometry techniques, including AMS, CIMS, and PTR-MS. Our measurements can be used to identify molecular tracers for chlorine-initiated oxidation chemistry during bleach cleaning. These results emphasize the importance of secondary chemistry during and after bleach cleaning activity.