Human skin oil: a major ozone sink indoors

Human skin oil contains numerous ozone-reactive constituents, including squalene, unsaturated fatty acids and unsaturated acylglycerols. Squalene is responsible for about half of the double bonds in skin oil, and unsaturated acyl groups are responsible for the other half. In occupied environments, skin oil is found on both human and non-human surfaces. Results from recent studies suggest that the surface density of skin oil double bonds on soiled indoor surfaces would be in the range 0.2-4 µmoles/m². Levels of double bonds close to this range have been measured on indoor vertical surfaces. The average concentration of double bonds on surfaces of all orientation is anticipated to be larger, given preferential particle deposition by settling onto upward facing surfaces. The findings highlighted in this report suggest that skin oil constituents are among the major sinks for ozone in indoor environments.