Fundamental study of horizontal wind velocity effect on PM2.5 and PM10 sampling accuracy of low-Cost sensors

Abstract

Low-cost PM sensors are widely used for air quality monitoring, yet their performance is influenced by many factors such as particle concentration and size, particle properties, relative humidity, and temperature etc. Laboratory and field calibrations are normally needed to correct for the potential bias of sensor readings. However, the effect of ambient wind velocity on the sensor flow rate and the particle sampling efficiency is rarely explored. This study conducted a fundamental study on the impact of horizontal wind velocity on the PM_2.5 and PM₁₀ sampling efficiency of low-cost PM sensors in a wind tunnel using NaCl and dust test particles. Results indicated that as wind velocity increased (0.35–3.26 m/s), the sampling flow rate and sampling efficiency of PM_2.5 and PM₁₀ decreased for both sensors. To calibrate the effect of the wind velocity on the sampling efficiency, a theoretical prediction model was developed with predicted results in good agreement with the experimental data. To mitigate the influence of horizontal wind velocity on the bias of the sensors, a Multi-Hole Inlet Cover (MHIC) was designed for the PMSX003, and test results showed significant improvement in PM_2.5 accuracy while PM₁₀ performance was also enhanced. This study demonstrates that horizontal wind velocity and sampling flow rate are critical factors affecting PM sensor accuracy and a validated model is useful for improving measurement reliability in high-wind conditions. It is also expected that the novel MHIC developed in this work could be used to improve the accuracy of monitoring data and expand its applicability across various environmental conditions.