AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Comparison of Reactive Oxygen Species (ROS) Generation Ability of Size Segregated Aerosols of Ambient Origin in Indoor and Outdoor Environments
HAORAN YU, Haoran Zhao, Brent Stephens, Vishal Verma, University of Illinois, Urbana, IL
Abstract Number: 798 Working Group: Indoor Aerosols
Abstract Exposure to ambient particulate matter (PM) is associated with increased risks of many adverse health effects including pulmonary disease, asthma, and heart attack. However, because people spend nearly 90% of their time indoors and ambient PM can infiltrate in and persist in buildings, much of human exposure to ambient PM occurs inside buildings. Although ambient PM mass concentrations have long been used in epidemiology studies, the oxidative potential (i.e., the ability of PM to generate reactive oxygen species, or ROS) of PM has been proposed as a more relevant health metric than PM mass. However, the oxidative potential of indoor PM has not been well characterized to date. In order to understand how the oxidative potential of PM of ambient origin changes as it infiltrates in persists indoors, we collected simultaneous size-segregated indoor and outdoor samples over the course of three weeks in an unoccupied student dormitory unit on the campus of Illinois Institute of Technology in Chicago, IL and measured the oxidative potential of both indoor and outdoor samples using a dithiothreitol (DTT) assay. An overall higher (2-5 times) intrinsic activity (i.e. DTT activity, the oxidation rate of DTT) was observed for the indoor PM than outdoor. The indoor PM mass was concentrated in the smaller size range (<0.5 μm), while outdoor PM was mostly concentrated in the larger sizes (1.5-7.0 μm). The intrinsic activity of the indoor PM was higher than the outdoor PM for all size ranges, but the indoor/outdoor (I/O) ratio peaked at around 1.0 μm. The results indicate that, consistent with penetration and deposition theory, the infiltration and persistence of outdoor PM concentrates mass in the ~0.1 to ~1 µm size range, which may contribute to changes in intrinsic oxidative potential of ambient PM. Moreover, aging of these particles in indoor environments may further increase the intrinsic oxidative potential. Given the higher concentrations of these toxic particles, exposure to the indoor PM could pose a more serious risk than previously considered.