Assessing PM2.5 Oxidative Potential in Fairbanks, Alaska Winter

YUHAN YANG, Peter F. DeCarlo, Ellis Robinson, Magesh K. Mohan, Jingqiu Mao, James Campbell, Rodney J. Weber, Georgia Institute of Technology

     Abstract Number: 119
     Working Group: Aerosols Spanning Spatial Scales: Measurement Networks to Models and Satellites

Abstract
We investigated the oxidative potential (OP) of fine particulate matter (PM_2.5) in Fairbanks, Alaska, during winter and compared it to winter Atlanta and Los Angeles (LA). Approximately 40 23.5-hr filter samples were collected during the 2022 winter heating season and analyzed for OP via the dithiothreitol (DTT) and OH-generation in synthetic lung fluid assays. Utilizing measured chemical species, multivariate linear regression identified transition metals, especially Fe and Cu, and organic species, such as AMS-quantified PAHs and HOA, as the prominent components driving the OP assays in Fairbanks. Although the average PM_2.5 mass concentration of 14.4 µg/m³ was only moderately higher in Fairbanks than in Atlanta and LA, the variability was much higher reaching over 80 µg/m³ during extreme cold events (< -30°C). In terms of exposure, on a per volume of air basis, OP_v^OH was lowest in Fairbanks and highest in LA, whereas for OP_v^DTT, Fairbanks was higher than Atlanta and lower than LA. Normalizing by particle mass, a measure of particle intrinsic health-related properties, gave similar results. Differences in OP^OH can be attributed to concentrations of transition metals, which the OH assay is sensitive to. Both Fe and Cu concentrations and their fractions of mass were substantially lower in Fairbanks, consistent with low traffic density. OP^DTT is sensitive to both organic species mainly associated with incomplete combustion and transition metals. Lower transition metals in Fairbanks may have been compensated by higher concentrations of OA species (e.g., PAHs and related compounds) from residential wood combustion leading to higher levels of OP^DTT compared to Atlanta, but high metals in LA appear to drive higher OP^OH and OP^DTT there. These findings demonstrate OP provides a distinct perspective on particle health-related properties compared to PM_2.5 mass.