Calibration of optical particle size spectrometers against a primary standard: Counting efficiency profile of the TSI Model 3330 OPS and Grimm 11-D monitor in the particle size range from 300 nm to 10 μm

Assessment of PM2.5 concentrations, transport, and mitigation in indoor environments using low-cost air quality monitors and a portable air cleaner

“…We chose the OPS as a comparison instrument for this study because it also operates on the principle of single particle counting using a laser and photodetector assembly. 46 It can measure particles in the size range of 0.3–10 μm (16 bins) with an inlet flow rate of 1 liter per minute. Its compact size and low pump noise make it suitable for indoor environments.…”

“…Although the OPS is not a regulatory reference instrument, it has been widely used in previous studies and has shown good agreement with other research-grade instruments. 46,47 The four AQM models used in this study are also listed in Table 1. Two identical units were deployed for each AQM model.…”

The Aerosol Research Observation Station (AEROS)

“…The OPS has been used previously in many laboratory settings (Ardon-Dryer et al, 2015;Yamada et al, 2015;Hsiao et al, 2016) and indoor experiments (Mølgaard et al, 2015;Maragkidou et al, 2018;Wang et al, 2020). Several studies that examined the performance of the OPS under diverse laboratory conditions have found it to be comparable to various reference units (Ardon-Dryer et al, 2015;Vasilatou et al, 2021). To the best of our knowledge, the OPS has not previously been used for atmospheric measurements or for monitoring atmospheric dust events.…”

“…The Grimm 11-D and previous versions have been used in various indoor (Mølgaard et al, 2015) and atmospheric studies (Mukherjee et al, 2017;Stavroulas et al, 2020;Masic et al, 2020), including under dusty conditions (Jaafari et al, 2018). Several studies examining the performance of the Grimm 11-D unit under diverse atmospheric and laboratory conditions have found it to be comparable to various reference units (Masic et al, 2020;Vasilatou et al, 2021). For example, Masic et al (2020) found that it performed well under diverse atmospheric and pollution conditions; when equipped with a dryer, it performed at a level comparable to that of a reference unit (a beta attenuation monitor).…”

“…Some of these units can provide information on multiple mass fractions of PM simultaneously, which is an advantage to the gravimetric system which provides the mass concentration of only a single fraction (Masic et al, 2020). Several studies have found mid-price optical particle sensors to be comparable to high-priced reference units as long as the mid-price optical particle sensors undergo a regular (e.g., yearly) ser-vice and re-calibration (Viana et al, 2015;Jaafari et al, 2018;Vasilatou et al, 2021).…”