Low-cost particulate matter (PM) sensors based on the light scattering principle measure the concentration of particles by the change of scattering intensity after light is irradiated onto the particles. It has been reported that when the relative humidity is high, water vapor may cause the expansion of airborne particles and affect the accuracy of the light scattering method for PM measurement, but it has also been shown that the effect of humidity is not significant or even negligible. Therefore, to determine the effect of humidity on the Plantower PMS7003 light scattering sensor, in this study, a BAM1020 (Beta Attenuation Monitoring) was installed alongside to continuously monitor the ambient atmospheric PM concentration for approximately four weeks. The sensors collected data at 10-minute intervals, resulting in a 1-hour average for comparative analysis. To accurately measure humidity, the performance of the Arduino + DHT22 humidity sensor was also pre-evaluated using a series of saturated salt solutions. The humidity was grouped into five intervals and analyzed by visual analysis. The results confirmed that there was no significant correlation between PM2.5 differences and humidity, which were randomly and uniformly distributed around the mean. However, since in the very low and high concentration ranges based on the beta-ray monitor measurements, the difference between the light scattering sensor PM10 measurement and the reference value is much larger than the difference between the PM2.5 and the reference value., there is an additional need to investigate the appropriate correction method for dust season or PM10. The results show that the outcomes of the light scattering sensor are more influenced by particle size and concentration than by humidity.

Abstract
1. Introduction
2. Experimental materials and methods
    2.1 Selection and calibration of humidity sensor
    2.2 Measurement of outdoor PM2.5, PM10 concentration
    2.3 Data processing and analysis
3. Results and discussions
    3.1 Basic Statistical Analysis
    3.2 Effect of PM concentration
4. Conclusion
Acknowledgements
References

• 김선태(대전대학교 토목환경공학과) | Sun-Tae Kim (Department of Environmental Engineering, Daejeon University) Corresponding Author
• 황운호(대전대학교 토목환경공학과) | Yunhao Huang (Department of Environmental Engineering, Daejeon University)
• 전형재(대전대학교 토목환경공학과) | Hyeong Jae Jeon (Department of Environmental Engineering, Daejeon University)
• 김건호(대전대학교 토목환경공학과) | Gun-Ho Kim (Department of Environmental Engineering, Daejeon University)
• 이휘(㈜엔버스) | Hui Li (Envors. Co., Ltd)