AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Assessing the Accuracy and Reliability of a Low-Cost Particle Counter for Determining PM1 Loadings Using a Fit-and-Integrate Approach
DAVID HAGAN, Rebecca Sugrue, Jesse Kroll, MIT
Abstract Number: 109 Working Group: Instrumentation and Methods
Abstract The past several years have seen the emergence of a number of low-cost commercial devices for measuring particulate matter (PM) for the monitoring of both indoor and outdoor air quality. Although these devices are beginning to see widespread use, very little is known about the accuracy and reliability of their data. In particular, most such monitors measure particle number concentration only, and 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. Low-cost PM counters are typically based on light scattering and cannot efficiently detect particles smaller than 500 nm, presenting challenges for estimating mass loadings of accumulation mode aerosol particles, especially in urban areas where a large fraction of the total mass is comprised of submicron aerosol particles. Here we explore the ability of a low-cost optical particle counter (Alphasense OPC-N2) to more accurately infer particle mass loadings through a process of fitting and integrating a volume-weighted histogram in real-time. Results will be presented comparing the ability of the OPC-N2 to accurately fit the particle size distribution as determined by an SMPS for a variety of laboratory-generated and ambient aerosol distributions. The integrate-and-fit approach will then be directly compared to existing approaches that either correlate the measured number concentration to a reference mass value or perform a step-wise volume integration across the histogram.