Reactive Oxygen Species on Indoor Surfaces

ZHENDUO YAO, Glenn Morrison, Ryan Moravec, UNC-Chapel Hill

     Abstract Number: 204
     Working Group: Indoor Aerosols

Abstract
Reactive Oxygen Species (ROS) are relatively unstable oxygen-containing radicals or non-radicals, some of which may react with tissues and biomolecules after entering human body. ROS is present on indoor aerosols but it is unclear how much is of indoor origin. As a potentially important source of ROS generation, indoor surfaces are now known to be coated with unsaturated hydrocarbons that can react with ozone and other oxidants. In this study, the ROS concentration on several indoor surfaces was measured using a xylenol orange ferrous oxidation assay after wiping and extraction. The preliminary results show that, on surfaces frequently touched by occupants, the concentration is about 0.2 nmol/cm²; this is two to three times greater than surface not frequently touched. In addition, kitchen surfaces exposed to cooking fumes contain even higher concentrations of peroxide, with some exceeding 0.5 nmol/cm². Based on this observation, we studied the development of ROS in laboratory experiments. To simulate the oxidation of unsaturated hydrocarbons on indoor surfaces, a soybean oil-acetone solution was dosed on 22 identical glass plates. The acetone evaporates almost immediately leaving a thin oil film. The ROS concentrations were measured daily. During the first 5-6 days, the ROS concentration increased roughly linearly. After this, the concentration on the glass surface tends to be stabilize, perhaps reflecting a balance between formation and decay of ROS.