You are here:
Precision and Accuracy of PM2.5 Monitors: Impacts on Air Sensor Evaluations
Citation:
Barkjohn, K., A. Clements, A. Holder, R. Vanderpool, B. Gantt, AND T. Hanley. Precision and Accuracy of PM2.5 Monitors: Impacts on Air Sensor Evaluations. American Association for Aerosol Research Conference, Research Triangle Park, NC, October 03 - 07, 2022.
Impact/Purpose:
Air sensors have grown in popularity in recent years. They have the potential to provide more spatially dense measurement than conventional monitors. However, to gather accurate data, collocation and comparison with conventional air monitors are often needed. The monitor type selected can impact perceived performance and researchers need to be aware of this to correctly interpret their findings. This work will be presented at the American Association for Aerosol Research Conference Oct 3-7, 2022, in Raleigh, NC.
Description:
PM2.5 sensors are typically collocated with conventional air monitors to better understand their performance. These monitors may include filter based federal reference methods (FRM), federal equivalent methods (FEM), temporary smoke monitors, research-grade methods, or other near-FEM technology. This work evaluates the strengths and limitations of these comparison methods and the implications for correctly interpreting sensor evaluation results. This work uses PurpleAir PA-II sensors collocated with a variety of monitors across the U.S. to explore the influence of comparison monitor type on perceived sensor performance. In addition, the bias of FEM Teledyne API T640 and T640x optical PM monitors has been evaluated to understand when these monitors are most suitable for sensor comparisons. The Teledyne T640 and T640x have become popular FEM choices in the past few years and provide precise measurements relative to FRMs at low concentrations. This work analyzes 3 years of collocated T640 and FRM data from across the U.S. to understand T640 and T640x bias compared to the FRM. Piecewise regression was used to understand nonlinearity at higher concentration. Findings suggest that FEM T640 and T640x data may have a nonlinear relationship with FRM concentrations above ~35 µg/m3. Understanding the strengths and limitations of monitors is crucial when using them to evaluate air sensors. Although this abstract was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.