Performance of Plantower PMS Sensors and the Alphasense Optical Particle Counter for Measuring PM10 Concentration in the Laboratory and Field

KERRY KELLY, Kamaljeet Kaur, Ross Whitaker, University of Utah

     Abstract Number: 200
     Working Group: Instrumentation and Methods

Abstract
Regulatory measurements of PM₁₀ (particulate matter, PM, smaller than 10 µm in diameter) are even sparser than regulatory measurements of PM_2.5 (PM smaller 2.5 µm in diameter). Although low-cost sensors could supplement regulatory monitors, most of these sensors are not effective at measuring PM₁₀ in spite of claims by sensor manufacturers. Elevated PM₁₀ concentrations can be important sources of PM pollution, particularly in arid regions of the US. The Salt Lake Valley is one area that faces such challenges. Climate change and receding levels of the Great Salt Lake have led to more than 750 mi² of exposed playa, and appropriate meteorological conditions cause dust events with elevated PM₁₀ concentrations, sometimes reaching 400 µg/m³. More highly resolved measurements of PM₁₀ would permit a better understanding of potential health risks and to identify hotspots. This study evaluated the laboratory and field performance of three versions of the Plantower PMS (3003, 5003, and 6003) and the Alphasense OPC-N3. Our preliminary results suggest that the PMS sensors severely underestimated PM10 concentration (~ factor of 10) compared to FEM measurements during a two month period that included four dust events. They also exhibited relatively poor correlation with FEM PM10 measurements (R² ~ 0.3 – 0.5). The OPC-N3 detected all the four dust events (slope of ~ 0.9 ) and exhibited better correlation with FEM PM₁₀ measurements (R² ~ 0.7) during this same period. In the laboratory, the study evaluated sensor performance and intra-sensor variability using a flow-focusing monodisperse aerosol generator and aerodynamic particle sizer. Overall, the Alphasense N3 OPCs appeared to be capable of measuring PM₁₀. It may be possible to combine a limited number of Alphasense OPC N3s with the widely distributed networks of PurpleAir and AirU sensors (Plantower PMS) to improve the spatial and temporal estimates of PM₁₀ concentration.