Real-Time Air Quality Monitoring Using Low-Cost Sensors – IoT System

Abstract—The quality of both indoor and outdoor air has been severely impacted,with increasing urban development and industrial emissions. As a result, there is a growing demand for systems capable of continuously monitoring environmental parameters. This project introduces an IoT-enabled air quality monitoring solution that keeps track of atmospheric conditions and promptly issues alerts when air pollution surpasses acceptable levels. A Raspberry Pi 3B serves as the central unit, interfaced with a DHT22 sensor for tracking humidity and temperature and an MQ-2 sensor—connected via an ADS1115 ADC—to detect harmful gases. To ensure user safety, the system includes a buzzer for immediate local alerts and integrates Twilio’s messaging API to send SMS notifications if the Air Quality Index (AQI) drops below 90. Simultaneously, real-time data is uploaded to ThingSpeak for cloud-based visualization and analysis. Compared to conventional systems that are often costly, static, or delayed, this design offers a more practical, economical, and accessible solution for real-time air quality management in homes or small institutions. The project demonstrates the feasibility of a modular, cost-effective monitoring system that can be expanded to meet broader smart city or environmental needs. Keywords: Air Quality Index (AQI), IoT, Raspberry Pi, DHT22, MQ-2, ADS1115, Twilio, ThingSpeak, Real-Time Monitoring, Alert System