A184-0011
Modeling reactions of ozone with human skin and clothing to quantify formation of semivolatile organic compounds

Tuesday, 15 December 2020
Poster
Pascale Lakey1, Andreas Zuend2, Glenn Morrison3, Nijing WANG4, Nora Zannoni4, Jonathan Williams4, Youngbo Won5, Donghyun Rim5 and Manabu Shiraiwa6, (1)University of California Irvine, Department of Chemistry, Irvine, CA, United States, (2)McGill University, Department of Atmospheric and Oceanic Sciences, Montreal, QC, Canada, (3)University of North Carolina at Chapel Hill, Department of Environmental Sciences and Engineering, Chapel Hill, NC, United States, (4)Max Planck Institute for Chemistry, Atmospheric Chemistry Department, Mainz, Germany, (5)Pennsylvania State University Main Campus, Architectural Engineering Department, University Park, PA, United States, (6)University of California Irvine, Department of Chemistry, Irvine, United States
Abstract:
Squalene is a major lipid in skin oil that contains six double bonds making it highly reactive with ozone. Squalene ozonolysis leads to a range of products including carbonyls, carboxylic acids, hydroxy ketones and secondary ozonides. Some of these products are known to be skin and respiratory irritants and it is therefore important to understand their formation pathways. It has recently been demonstrated that relative humidity plays an important role in the types and concentrations of products which form from squalene ozonolysis [1,2]. Water can react with Criegee Intermediates leading to an increase in the concentration of carbonyls and a decrease in the concentration of other products. Measurements during the Indoor Chemical Human Emissions and Reactivity (ICHEAR) project have provided a quantification of squalene ozonolysis products emitted from soiled clothing. We have developed the kinetic multilayer model of surface and bulk chemistry of the skin and clothing (KM-SUB-Skin-Clothing) [3] which treats mass transport of chemical species as well as chemical reactions in the gas phase, clothing and skin. In this work a more complex squalene ozonolysis mechanism was added to the model and the formation of Criegee Intermediates and their subsequent reactions in both the gas and condensed phase was explicitly treated. The thermodynamic partitioning of water into squalene and skin oil was also investigated using the thermodynamic model AIOMFAC. The rate coefficients and branching ratios in the mechanism are constrained by reproducing measurements of squalene ozonolysis products which were obtained when exposing pure squalene particles to different ozone concentrations and relative humidities [1, 2]. Additionally, we treat the reaction of fatty acids present in skin oil with Criegee Intermediates, with the rate being constrained by experimental measurements [4]. Furthermore, computational fluid dynamics simulations were conducted to showcase spatial heterogeneity of gas phase products. The model can also estimate gas phase emissions due to indoor-to-outdoor transport.

References

[1] Arata et al., Environ. Sci. Tech. 53, 14441-14448 (2019), [2] Heine et al. Environ. Sci. Tech. 51, 13740-13748 (2017), [3] Lakey et al., Comms. Chem. 2, 56 (2019), [4] Zhou et al. Environ. Sci. Technol. Lett. 3, 170−174 (2016).

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