Low-cost PM2.5 Sensors: An Assessment of Their Suitability for Various Applications

Abstract

Recently, there has been a substantial increase in the availability and use of low-cost particulate matter sensors in a wide range of air quality applications. They carry the promise of revolutionising air quality monitoring, yet considerable reservations exist regarding their performance and capabilities, thus hindering the broader-scale utilization of these devices. In order to address these concerns and assess their feasibility and accuracy for various applications, we evaluated six low-cost PM 2.5 sensors (the Sharp GP2Y1010AU0F, Shinyei PPD42NS, Plantower PMS1003, Innociple PSM305, Nova SDS011 and Nova SDL607) in laboratory and field conditions using two combustion aerosols, concrete dust and ambient particles. In assessing the performance of these sensors, we focussed on indicators such as the linearity, accuracy and precision, critically differentiating between these qualities, and employed inter-comparison (the coefficient of determination, R 2 ). In the laboratory, all sensors responded well, with an R 2 > 0.91 when the PM 2.5 concentration was > 50 µg m -3 , as measured by the DustTrak. In particular, the PMS1003 demonstrated good accuracy and precision in both laboratory and ambient conditions. However, some limitations were noted for the tested sensors at lower concentrations. For example, the Sharp and Shinyei sensors showed poor correlations (R 2 < 0.1) with the DustTrak when the ambient PM 2.5 concentration was < 20 µg m -3 . These results suggest that the sensors should be calibrated individually for each source in the environment of their intended use. We demonstrate that when tested appropriately and used with a full understanding of their capabilities and limitations, low-cost sensors can serve as an unprecedented aid in a broad spectrum of air quality applications, including the emerging field of citizen science.

Field Evaluation of Low-Cost Particulate Matter Sensors for Measuring Wildfire Smoke

“…All sensors exhibited a high bias, consistent with other field evaluations of the PA [ 7 , 16 , 21 , 29 , 30 ] and other optical-based sensors [ 8 , 15 , 16 , 19 ]. Additionally, the sensors evaluated here had higher correlations to the reference than most field studies using optical-based sensors (0.3 < r 2 < 0.95) [ 10 ].…”

“…This was likely due to the much higher PM concentrations encountered near fires, where many more hourly averages are above the lower detection limits of both the sensors and the reference instruments [ 21 ]. Sensor performance during smoke impacted times was more similar to the high correlations observed in laboratory evaluations, where the concentration range is much larger and aerosol characteristics are roughly constant [ 14 , 16 , 19 ]. The sensors evaluated here also exhibited a linear response up to the very unhealthy AQI level (150.5–250.5 µg/m 3 ), meaning that with a simple linear correction these sensors may be useful for identifying appropriate health guidance during wildfires.…”

“…However, sensor performance has varied by manufacturer and model, even when using the same original equipment manufacturer (OEM) sensor, demonstrating the importance of the physical configuration of the sensor package, sensor design (e.g., laser, light detector, flow path, etc. ), and data processing algorithms [ 11 , 15 , 16 , 17 , 18 ].…”

“…Additionally, environmental conditions can impact accuracy [ 20 , 21 ]. Some sensors have exhibited a high bias (up to 50%) with increasing temperature (T) [ 16 ] and increasing relative humidity (RH) (up to 90% when RH exceeded 75%) [ 7 , 10 , 20 , 21 ]. The sensitivity to RH may depend on particle composition, with PM hygroscopicity playing an important role [ 19 , 20 ].…”

Facility for generation of ambient-like model aerosols in the laboratory: application in the intercomparison of automated PM monitors with the reference gravimetric method

“…chemistry) and humidity, and research findings suggest that a rigorous calibration with "tailored" aerosols, i.e. aerosols representative of the environment of their intended use, is needed (Jayaratne et al, 2020;McNamara et al, 2011).…”