Abstract
Despite the fact that precursors to reactive oxygen species (ROS) are prevalent in homes, the concentration of ROS had not been assessed in homes till a recent study by our group. Given the significant concentrations of ROS that we found in homes as well as the evidence for adverse health effects caused by ROS, it becomes important to identify and control potential sources of indoor ROS. Controlled experiments were conducted at an unoccupied test house to help determine the influence of two potential outdoor sources of indoor ROS: outdoor particles and ozone (O3) that infiltrate into homes. One of the rooms was pressurized to isolate it from the rest of the house and sampling was conducted in three different situations: (i) particle-free, O3 laden air brought into the room using a High Efficiency Particulate Air (HEPA) filter at the room’s inlet, (ii) O3-free, particle laden air brought in using an activated carbon (AC) filter, and (iii) clean air brought in using HEPA and AC filters. The concentration of ROS on triplicate total suspended particle (TSP) samples was assessed with a fluorescent reagent. When the O3 concentration in the room was increased to 19 ppb, the ROS concentration in the room (1.50±0.38 nmoles/m3) was closer to the outdoor concentration (2.08±0.20 nmoles/m3) where O3 was at 40 ppb, than in the rest of the house (0.75±0.11 nmoles/m3) where O3 had remained at 3 ppb. When the PM2.5 concentration in the room was increased to 2.6 mg/m3, the ROS concentration in the room (2.26±0.42 nmoles/m3) was similar to the outdoor concentration (2.42±0.58 nmoles/m3) where PM2.5 concentration was at 3.1 mg/m3. In comparison, when no O3 or particles were brought into the room, the ROS concentration in the room (2.00±0.24 nmoles/m3) was substantially below the outdoor concentration (2.95±0.08 nmoles/m3). These results indicate that infiltration of outdoor particles and O3 into homes can strongly influence indoor particulate ROS concentrations.
Published Version
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