Ozone-Initiated Yield of Reactive Oxygen Species in a Model Indoor Surface Film

Recent evidence suggests that products of indoor ozonechemistrycontribute to cardiovascular pathophysiology. A hypothetical exposurepathway is the formation of reactive oxygen species (ROS) on indoorsurfaces, and subsequent partitioning of ROS to respirable particulatematter (PM). For this pathway to be relevant, the ozone-initiatedsurface yield of ROS should be large enough to contribute substantiallyto total ROS intake by PM. Here, we exposed a model indoor surfacefilm comprising a mixture of skin and cooking oil lipids to ozoneand measured the yield of condensed-phase ROS using a colorimetricmethod sensitive primarily to hydroperoxides and calibrated with hydrogenperoxide. Approximately 46% of the ozone that was consumed in thereaction formed ROS on a molar basis. Approximately half of the ROSformed is persistent for at least several hours on the surface. ROScontinued to form in the absence of ozone, suggesting that a mechanismother than ozonation continues to oxidize the lipids, such as autoxidation.The yields observed here are well above that necessary to contributeto the ROS airborne concentrations observed in field studies.