Abstract View
Indoor Mopping with a Terpene-Based Cleaner in the Presence of Ozone Initiates the Rapid Formation of Peroxy Radicals, Volatile Oxidation Products, and Secondary Organic Aerosols
COLLEEN MARCIEL ROSALES, Jinglin Jiang, Ahmad Lahib, Vinay Kumar, Emily Reidy, Brandon Bottorff, Alexandre Tomas, Sebastien Dusanter, Antonios Tasoglou, Heinz Huber, Brandon E. Boor, Philip Stevens, Indiana University
Abstract Number: 256
Working Group: Indoor Aerosols
Abstract
Indoor air pollutants, in both gaseous and particle (aerosol) forms, may be either directly emitted or chemically generated (i.e. secondary formation) from common activities such as cleaning. Secondary formation of aerosols is less understood indoors compared to ambient air pollution. In addition, there have been few direct, real time measurements of intermediates, none of which precisely point to secondary formation of aerosols indoors. In the quickly emerging field of indoor chemistry, a complete understanding of the chemical mechanisms of secondary aerosol formation is critical in protecting human health indoors, especially for workers repeatedly exposed to cleaning agents at workplaces.
To aid in understanding secondary aerosol formation, various instruments that measure gas- and aerosol-phase species were deployed to the Indiana University Research and Teaching Preserve during the summer of 2019. Indoor cleaning activities were simulated by mopping and wiping surfaces in a sunlit room provided with outdoor air via a mechanical ventilation system. Application of a commonly used commercial household cleaner released a mixture of monoterpenes (e.g. limonene), monoterpenoids (e.g. citral), and monoterpene alcohols (e.g. terpineol), with monoterpene concentrations reaching ~250 to 400 ppb. Immediately thereafter, HO2 and RO2 radicals (peak: ~3×109 molecules cm-3) and volatile monoterpene oxidation products, such as limononic acid, limonalic acid, and limononaldehyde, were observed, quickly followed by new particle formation and growth starting from ~1 nm (peak number concentration: ~105 cm-3 for particles below 100 nm). Radical and aerosol concentrations reached levels that are comparable to outdoor traffic-impacted areas, emulating “indoor smog” for a few minutes. It was found that aerosol formation indoors during these events are highly driven by the ozonolysis of the monoterpene mixtures found in cleaning products when indoor ozone levels are ~5 to 10 ppb. Current models for radicals and aerosol formation reasonably estimate the measured concentrations, albeit underestimating the measurements up to about a factor of 2, suggesting an incomplete understanding of the indoor oxidation mechanisms due to sources that were unaccounted for, e.g. surface films as reservoirs. These results lay the foundation for regulatory policies on issues such as permissible compositions of household cleaning products and residential and workplace building regulations for ventilation systems.