This research shows how to develop a smartphone-based system to control air exchangers for better indoor air quality and easier use. The system uses sensors to check CO₂, temperature, humidity, VOCs, PM2.5, and PM10. All values are shown on a local TFT display and a special Android app. The system uses MQTT for communication, so it can control and send data in real-time over the internet. The test was done in a small indoor area. The system could be used in two ways: by hand or automatic. The automatic mode worked when PM2.5 was over 50 µg/m³ or CO₂ was over 800 ppm. Sensors used were PMS5003, SGP30, and SHT30. NodeMCU microcontroller was used to control the system. The satisfaction of 30 users was checked using a post-test survey. The results showed that the remote control and fan speed adjustment worked with 100% accuracy. Users gave the app an average score of 4.05 out of 5, which means they liked it. The system is a good example of how IoT can help improve air quality and comfort, especially in schools or offices. However, it needs the internet to work well and has limits with the RF signal range. In the future, AI can help the system respond better and work in many rooms.