Smart IoT-Based Indoor Air Quality Monitoring and Human Health Assessment Using ESP32 Microcontroller and MQ-135 Gas Sensor

Indoor air pollution has emerged as a significant environmental and public health challenge due to increasing urbanization, inadequate ventilation, and the presence of harmful gaseous pollutants. Prolonged exposure to poor indoor air quality can contribute to respiratory disorders, headaches, fatigue, and other adverse health effects. Therefore, continuous monitoring of indoor environmental conditions is essential for safeguarding human health and improving living and working environments.

This study presents a Smart Internet of Things (IoT)-based Indoor Air Quality Monitoring System utilizing a low-cost ESP32 microcontroller and MQ-135 gas sensor for real-time assessment of air quality. The MQ-135 sensor is employed to detect a range of air pollutants, including smoke, ammonia, benzene, and other harmful gases that influence indoor air quality. In addition, temperature and humidity parameters are monitored to provide a comprehensive assessment of environmental conditions. The acquired sensor data are processed by the ESP32 and transmitted to a cloud-based platform via Wi-Fi for real-time visualization, storage, and analysis.

The proposed system incorporates threshold-based air quality evaluation and health-risk notification mechanisms to alert users when pollutant concentrations exceed recommended levels. Experimental deployment in different indoor environments demonstrates the capability of the system to detect variations in air quality and provide timely information for preventive action. The developed framework offers a cost-effective, scalable, and user-friendly solution for continuous environmental monitoring and public health awareness. Furthermore, the proposed system has potential applications in smart homes, educational institutions, offices, healthcare facilities, and smart city infrastructures to promote healthier indoor environments and sustainable environmental management.