Modelling indoor radical chemistry during the HOMEChem campaign

Freja F Østerstrøm; Toby J Carter; David R Shaw; Jonathan P D Abbatt; Andrew Abeleira; Caleb Arata; Brandon P Bottorff; Felipe J Cardoso-Saldaña; Peter F DeCarlo; Delphine K Farmer; Allen H Goldstein; Lea Hildebrandt Ruiz; Tara F Kahan; James M Mattila; Atila Novoselac; Philip S Stevens; Emily Reidy; Colleen Marciel F Rosales; Chen Wang; Shan Zhou; Nicola Carslaw

doi:10.1039/d4em00628c

Modelling indoor radical chemistry during the HOMEChem campaign

Environ Sci Process Impacts. 2024 Dec 17. doi: 10.1039/d4em00628c. Online ahead of print.

Authors

Freja F Østerstrøm¹, Toby J Carter¹, David R Shaw¹, Jonathan P D Abbatt², Andrew Abeleira³, Caleb Arata^{4

5}, Brandon P Bottorff⁶, Felipe J Cardoso-Saldaña⁷, Peter F DeCarlo⁸, Delphine K Farmer³, Allen H Goldstein^{5

9}, Lea Hildebrandt Ruiz⁷, Tara F Kahan^{10

11}, James M Mattila³, Atila Novoselac¹², Philip S Stevens^{6

13}, Emily Reidy⁶, Colleen Marciel F Rosales¹³, Chen Wang², Shan Zhou^{10

14}, Nicola Carslaw¹

Affiliations

¹ Department of Environment and Geography, University of York, York, UK. [email protected].
² Department of Chemistry, University of Toronto, Toronto, Canada.
³ Department of Chemistry, Colorado State University, Fort Collins, CO, USA.
⁴ Department of Chemistry, University of California Berkeley, Berkeley, CA, USA.
⁵ Department of Environmental Science, Policy and Management, University of California Berkeley, Berkeley, CA, USA.
⁶ Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA.
⁷ McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA.
⁸ Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, MD, USA.
⁹ Department of Civil and Environmental Engineering, University of California Berkeley, Berkeley, CA, USA.
¹⁰ Department of Chemistry, Syracuse University, Syracuse, NY, USA.
¹¹ Department of Chemistry, University of Saskatchewan, Saskatoon, Canada.
¹² Department of Civil, Architectural, and Environmental Engineering, University of Texas at Austin, Austin, TX, USA.
¹³ O'Neill School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, IN, USA.
¹⁴ Department of Civil and Environmental Engineering, Rice University, Houston, TX, USA.

PMID: 39688182
DOI: 10.1039/d4em00628c

Abstract

In the indoor environment, occupants are exposed to air pollutants originating from continuous indoor sources and exchange with the outdoor air, with the highest concentration episodes dominated by activities performed indoors such as cooking and cleaning. Here we use the INdoor CHEMical model in Python (INCHEM-Py) constrained by measurements from the House Observations of Microbial and Environmental Chemistry (HOMEChem) campaign, to investigate the impact of a bleach cleaning event and cooking on indoor air chemistry. Measurements of the concentrations of longer-lived organic and inorganic compounds, as well as measured photolysis rates, have been used as input for the model, and the modelled hydroxyl (OH) radicals, hydroperoxyl radicals, and nitrous acid (HONO) concentrations compared to the measured values. The peak modelled OH, , and HONO concentrations during cooking and cleaning activities are about 30%, 10%, and 30% higher than the observations, respectively, within experimental uncertainties. We have determined rates for the rapid loss of HONO formed through cooking activities onto a wet surface during the cleaning events and also for the subsequent slow release of HONO from the cleaned surface back into the gas-phase. Using INCHEM-Py we have also predicted peak concentrations of chlorine (Cl) atoms, (0.75-2.3) × 10⁵ atom per cm³ at the time of cleaning. Model predictions of the Cl atom and OH radical reactivities were also explored, showing high Cl atom reactivity throughout the day, peaking around 5000-9000 s^-1. The OH reactivity was found to increase from a background value close to urban outdoor levels of 20-40 s^-1, to levels exceeding observations in outdoor polluted areas following cooking and cleaning activities (up to 160 s^-1). This underlines the high oxidation capacity of the indoor atmospheric environment through determining the abundance of volatile organic compounds.