The IAQ has been recognized as a significant factor in the determination of the health and welfare of people. In this study, the air quality monitoring system based on environmental sensors was implemented to display and record the data on PM10, CO2, radon concentration, temperature, and humidity. In addition, a USN monitoring system is implemented to display and record the environmental sensor data measured in an underground subway station. To transmit and receive these measured sensor data, Wi Fi wireless communication is applied. Tae-In Hyon | Gyu-Sik Kim "Indoor Air Quality Monitoring System for Underground Subway Stations" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26603.pdf