Reactions and Products of Squalene and Ozone: A Review

reaction, or squalene ozonolysis. Ambient ozone penetrates indoors and drives indoor air chemistry. Squalene, a component of human skin oil, contains six carbon???carbon double bonds and is very reactive with ozone. Bioeffluents from people contribute to indoor air chemistry and affect the indoor air quality, resulting in exposures because people spend the majority of their time indoors. The SqOz reaction proceeds through various formation pathways and produces compounds that include aldehydes, ketones, carboxylic acids, and dicarbonyl species, which have a range of volatilities. In this critical review of SqOz chemistry, information on the mechanism of reaction, reaction probability, rate constants, and reaction kinetics are compiled. Characterizations of SqOz reaction products have been done in laboratory experiments and real-world settings. The effect of multiple environmental parameters (ozone concentration, air exchange rate (AER), temperature, and relative humidity (RH)) in indoor settings are summarized. This critical review concludes by identifying the paucity of available exposure, health, and toxicological data for known reaction products. Key knowledge gaps about SqOz reactions leading to indoor exposures and adverse health outcomes are provided as well as an outlook on where the field is headed.

Automated summary

Ambient ozone can penetrate indoors and participate in indoor air chemistry. This review focuses on the reaction between squalene, a component of human skin oil, and ozone. It summarizes the reaction mechanism, products characterization, and the effects of various environmental parameters on this reaction in indoor settings. The review highlights the lack of available exposure, health, and toxicological data for known reaction products and provides insights into future research directions.