Performance Validation of Low-Cost Air Quality Sensors

Inhalation exposure to airborne particulate matter is closely linked to human health and comfort. National regulatory agencies utilize high-precision air quality instruments to monitor ambient air pollution; however, such instruments are often expensive and not practical for widespread building applications. Gathering indoor air data for building occupants can help address occupants' needs and improve public health. The main objective of this study is to validate the performance of a low-cost air quality sensor that monitors both particulate matter and total volatile organic compounds (TVOC). The present study involves experiments with three different environmental settings: 1) 240-L laboratory chamber, 2) one-person office, and 3) highly occupied cafeteria. A popular low-cost sensor, Samyoung’s Dust Sensor Module MDG 501S, was tested. The sensor had a small module with a particle counter and gas sensor inside. The low-cost sensor was validated with laboratory grade sensors: TSI AeroTrak Handheld Optical Particle Counter Model 9306 for particles and ppbRAE PGM-7240 gas sensor for TVOC. The laboratory chamber test results indicate that the low-cost sensor gives accurate readings for high particle concentrations (> 1000/m³) in the chamber. However, the accuracy and sensitivity decrease with lower concentrations that could be easily found in buildings. The sensor readings from the one-person office are highly correlated with occupancy, likely due to particle resuspension from flooring/clothing and skin shedding during occupancy. However, the sensor accuracy observed in a highly occupied cafeteria was the lowest and showed high variations in concentrations. In this environment, increased human activities seem to cause fluctuations in airflow and airborne particle concentrations, which could be difficult for the low-cost sensor to monitor. Nonetheless, the study results imply that the low-cost sensor system has potential applications in indoor air quality monitoring and pollutant control in occupied spaces.