The Yield of Oxygenated VOCs from Ozone Deposition on Aged Indoor Surfaces

Ozone (O₃) loss on surfaces forms oxygenated VOCs (OVOCs) that can cause adverse health effects. Previous studies have focused on surface ozonolysis of pure unsaturated compounds on impermeable surfaces, whereas other work has addressed this chemistry in genuine indoor environments. Our goal is to bridge this gap by examining O₃ loss and OVOC production on glass and paint in both laboratory experiments, using surfaces purposefully contaminated with pure compounds (squalene, triolein), complex oils (skin, olive), and surfaces that were aged in an occupied apartment. Paint was chosen as a permeable and reactive material, which is the most common indoor surface. It was found that paint aged indoors had lower OVOC yields than glass when exposed to O₃, probably because O₃ reacts with paint materials rather than with deposited organics. Many OVOCs were measured, including common skin oil ozonolysis products such as acetone, 6-MHO, and 4-OPA; however, the OVOCs with the highest yields from the apartment samples were nonanal and hexanal, with the OVOC levels highly correlated with the amount of cooking that occurred. Experiments using pure compounds and complex oils produce OVOC species similar to those observed on surfaces aged in the apartment.