AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Laboratory and Field Evaluation of Real-time and Near Real-time PM2.5 Smoke Monitors
HANS MOOSMULLER, Ahmed Mehadi, David Campbell, Walter Ham, Donald Schweizer, Leland Tarnay, Julie Hunter, Desert Research Institute
Abstract Number: 327 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract Increases in wildfire frequency and intensity and a longer fire season in the western USA are resulting in a significant increase in air pollution, including PM2.5 concentrations that pose significant health risks to nearby communities. During wildfires, government agencies monitor PM2.5 mass concentrations providing information and actions needed to protect affected communities; this requires continuously measuring instruments. This study assessed the performance of seven candidate instruments: (1) Met One Environmental beta attenuation monitor (EBAM), (2) Met One ES model 642, (3) Grimm Environmental Dust Monitor 164 (EDM), (4) Thermo ADR 1500 (ADR), (5) TSI DRX model 8543 (DRX), (6) Dylos 1700, and (7) Purple Air II in comparison with a BAM 1020 (BAM) reference instrument. With the exception of the EBAM, all candidates use light scattering to determine PM2.5 mass concentrations. Our comparison study included environmental chamber and field components, with two of each candidate instrument operating next to the reference instrument. The chamber component involved six days of comparisons for biomass combustion emissions. The field component involved operating all instruments in an air monitoring station for 39.5 days with hourly average relative humidity (RH) ranging from 19% to 98%. Goals were to assess instrument precision and accuracy and effects of RH, elemental (EC), and organic carbon (OC) concentrations. All replicate candidate instruments showed high hourly correlations (R2≥0.80) and higher daily average correlations (R2≥0.90), where all instruments correlated well (R2≥0.80) with the reference. The DRX and Purple Air overestimated PM2.5 mass concentrations by a factor of ~two. Differences between candidates and reference were more pronounced at higher PM2.5 concentrations. All optical instruments were affected by high RH and by the EC/OC ratio. Equations to convert candidate instruments data to FEM BAM type data were developed to enhance usability of data from candidate instruments.