Laboratory evaluation of particle-size selectivity of optical low-cost particulate matter sensors

Abstract

Abstract. Low-cost particulate matter (PM) sensors have been under investigation as it has been hypothesized that the use of low-cost and easy-to-use sensors could allow cost-efficient extension of the currently sparse measurement coverage. While the majority of the existing literature highlights that low-cost sensors can indeed be a valuable addition to the list of commonly used measurement tools, it often reiterates that the risk of sensor misuse is still high and that the data obtained from the sensors are only representative of the specific site and its ambient conditions. This implies that there are underlying reasons for inaccuracies in sensor measurements that have yet to be characterized. The objective of this study is to investigate the particle-size selectivity of low-cost sensors. Evaluated sensors were Plantower PMS5003, Nova SDS011, Sensirion SPS30, Sharp GP2Y1010AU0F, Shinyei PPD42NS, and Omron B5W-LD0101. The investigation of size selectivity was carried out in the laboratory using a novel reference aerosol generation system capable of steadily producing monodisperse particles of different sizes (from ∼0.55 to 8.4 µm) on-line. The results of the study show that none of the low-cost sensors adhered to the detection ranges declared by the manufacturers; moreover, cursory comparison to a mid-cost aerosol size spectrometer (Grimm 1.108, 2020) indicates that the sensors can only achieve independent responses for one or two size bins, whereas the spectrometer can sufficiently characterize particles with 15 different size bins. These observations provide insight into and evidence of the notion that particle-size selectivity has an essential role in the analysis of the sources of errors in sensors.

Evaluation of optical particulate matter sensors under realistic conditions of strong and mild urban pollution

“…Newer methods, based on optical particle sensors (OPS), are nowadays increasingly more popular, particularly lowcost variants (Zheng et al, 2019;Mukherjee et al, 2019;Tanzer et al, 2019;Morawska et al, 2018). Their typical time resolution is between 1 s and 1 min, and because of their price and size, they can be used in networks to provide better spatial coverage (Martin et al, 2019;Li et al, 2019). Furthermore, they provide information about multiple mass fractions of particulate matter simultaneously, unlike the concentration of a single fraction in a gravimetric system or BAM.…”

Comparison of Low-Cost Particulate Matter Sensors for Indoor Air Monitoring during COVID-19 Lockdown

“…Therefore, the data produced should be used with care, and data correction is often suggested due to the disagreement with reference devices [ 14 , 22 , 23 , 24 , 25 ]. Comparison to the reference aerosol spectrometer (Grimm 1.108) showed that low-cost sensors, including PMS5003 used in this study, showed different performance than declared by the manufactures and provided a proper response in a limited range of bins [ 26 ]. On the other hand, the PMS series sensor showed a higher measurement quality than the Alphasense OPC-N2 (the previous model of the one used in our study) [ 27 ].…”

Evaluation of optical particulate matter sensors under realistic conditions of strong and mild urban pollution

“…It seems that the Plantower PMS5003 can not accurately determine the PM 10 fraction. One possible explanation is provided by a laboratory test of PMS5003, where it was found that its size bin [2.5 µm-10 µm] is noisy and inaccurate (Kuula et al, 2020). Further investigation of this behavior would be useful.…”

“…Laboratory tests and calibrations of OPS are performed under controlled conditions with known aerosols, such as polystyrene latex spheres (Walser et al, 2017;Bezantakos et al, 2018), continuously changing monodisperse, particles (Kuula et al, 2017(Kuula et al, , 2020 or multi-modal aerosols (Cai et al, 2019). Burning chamber is used in some investigations as well (Wang et al, 2015).…”