A systematic investigation on the effects of temperature and relative humidity on the performance of eight low-cost particle sensors and devices

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Low-cost particle sensors are rapidly gaining popularity for indoor air quality monitoring, but their accuracy has been shown to vary among products and among environments in which they operate. Previous research has explored the effect of environmental conditions including temperature and humidity on sensor accuracy and found appreciable effects of these variables in many cases. We extend this work to cover some models that have not been previously tested and analyze results in a way to establish the significance of environmental variables on low-cost sensor output. In this study, we conduct a series of laboratory experiments in which temperature and relative humidity (RH) are varied in a precisely controlled chamber and different common particle sources introduced. Eight different brands of low-cost particle sensors, some of which have not been previously analyzed in this manner, measured particle concentration inside the chamber and were compared to research-grade instruments. Comparison of the output of the research-grade instruments with that of the low-cost sensors yielded a few interesting results. First, temperature showed no statistically significant effect on sensor performance in any case, at 99% confidence. Second, RH appears to affect the magnitude of low-cost sensor output but not its correlation to research-grade instruments output, suggesting the possibility of RH-based calibration.