Low-Cost IoT Mesh Network for Real-Time Indoor Air Quality Monitoring

Indoor air quality (IAQ) has become an increasingly important consideration due to its impact on human health and well-being. Many existing IAQ monitoring systems are expensive, complex, and difficult to scale for widespread deployment, especially in residential and small commercial settings. This paper presents a low-cost and scalable Internet of Things (IoT)-based solution for real-time IAQ monitoring using the ESP32-S3 microcontroller, MQ-135 gas sensor, and DHT11 temperature and humidity sensor. The system utilizes Bluetooth Low Energy (BLE) for communication, enabling wireless transmission of data to mobile devices from IoT nodes. The network uses the ESP-NOW protocol to create a robust mesh network that enables efficient data transmission across large indoor spaces. The design prioritizes low power consumption, ease of deployment, and cost-effectiveness, making it suitable for smart home and small-scale commercial applications. The proposed solution aims to address the limitations of traditional IAQ monitoring systems, which are often expensive, difficult to scale, and lack real-time, easily accessible data. The system measures key IAQ parameters, including CO2, temperature, and humidity, providing real-time data accessible through a mobile app. The calibration of the designed IoT nodes accomplished through industry standard “Extech SD800: CO2, Humidity and Temperature Datalogger”, Experimental results demonstrate the system's accuracy, reliability, and low power consumption, making it a promising solution for continuous IAQ monitoring.