AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Assessing the Accuracy and Reliability of Low-cost Particle Sensors for Quantifying Fine Particulate Matter
DAVID HAGAN, Eben Cross, Timothy Onasch, John Jayne, Douglas Worsnop, Jesse Kroll, MIT
Abstract Number: 355 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract The past several years has seen the emergence of many low-cost commercial devices for measuring particulate matter (PM). While these devices are beginning to see widespread use, little is known about their ability to accurately and repeatedly quantify fine particulate matter under realistic, dynamic conditions. Most commercially available devices can be classified as either photometers, integrating nephelometers, or optical particle counters; each of these technologies has strengths and weaknesses, but none measure mass directly. Thus, the extent to which they can be used to estimate particle mass concentration, the quantity on which most health-based assessments and PM regulations are based, is unclear. One of the key limitations for low-cost particle sensors is their inability to measure small particles (in the case of optical particle counters) and/or measure the underlying particle size distribution (in the case of nephelometers and photometers), which represent potential sources of error in PM mass measurements, especially in dynamic environments. Additionally, proprietary algorithms used by various sensor manufacturers to convert raw signal to concentration introduce additional challenges to such measurements. Here, we report the results of controlled laboratory experiments to explore the ability of several commonly-used low-cost (Alphasense OPC-N2, Alphasense OPC-N3, Plantower PMS5003, Particles Plus OEM, Handix POPS, GRIMM) and Federal Equivalent Method (FEM) particle sensors (Teledyne T640) to accurately quantify PM for particles across a range of sizes, optical properties, and relative humidities. Results will be presented comparing the ability of these devices to count and size particles relative to reference instruments (SMPS, CPC), as well as the relative strengths and weaknesses of the different instrument types (i.e. nephelometer vs. photometer vs OPC) for measuring particulate matter concentrations.