Indoor Air Quality Monitoring Using IoT and Real-Time Sensors : A study of CO2, Temperature, and Humidity in Smaller Indoor Environments

Sammanfattning

Indoor air quality has a direct impact on human health, comfort, and cognitive performance, particularly in enclosed environments such as classrooms and offices. Despite the availability of IoT-based monitoring solutions, many existing systems areeither too expensive or too complex for practical use in smaller indoor settings. This project investigates whether a simple and affordable IoT-based system can reliablymonitor indoor air quality in real-time. A prototype was developed using a Raspberry Pi Pico W microcontroller connected to a DHT22 temperature and humidity sensor and an SCD40 CO2 sensor, with data transmitted via MQTT to the AdafruitIO dashboard for visualisation. Environmental data was collected continuously overone week in a classroom environment and compared against both recommended indoor air quality standards and a calibrated reference sensor. The results showed that CO2-levels varied clearly with classroom occupancy, temperature remained stable within recommended ranges, and humidity was occasionally below the recommended threshold. The low-cost sensors showed measurable deviations from thereference instrument but followed consistent trends, suggesting they are sufficient for general indoor air quality monitoring in smaller environments