Field Evaluation of Community Condensation Particle Counters, Optical Particle Counters, and a Low-Cost Particle Sensor.

Low-cost particulate matter (PM) sensors typically use light scattering to estimate mass concentrations, separated into several size fractions. Nevertheless, many of these sensors perform poorly when quantifying larger particles (e.g., PM10-2.5 or PM10). They are unable to assess the concentration of ultrafine particles below 0.1 μm. This study evaluated a novel Community Condensation Particle Counter (cCPC) that reports the number concentration of 0.005-2.5 μm particles, an optical particle counter (OPC) that reports 0.3-10 μm particle number distributions, and a low-cost sensor (Sensirion SPS30 in a TSI BlueSky™ package) that reports PM2.5 and PM10 mass concentrations. Three cCPCs, three OPCs, and one BlueSky were collocated at an urban air quality monitoring station. The cCPCs and OPCs continuously operated for about four months with data recovery rates >98%. When regressed against a research-grade reference CPC, the cCPCs had coefficients of determination (R2) >0.99, with mean cCPC/reference CPC concentration ratios close to unity. The three collocated cCPCs exhibited a coefficient of variation of 3%. Fine and coarse particle volumes by the OPCs were correlated with the reference PM2.5 and PM10-2.5 mass, respectively, but with different linear regression slopes. PM2.5 mass concentrations by the BlueSky were correlated with reference instruments, but the BlueSky was unable to accurately measure coarse particle concentrations.