Implementation of a Low-Cost IoT-Based Environmental Monitoring Node for Industrial Areas in Port Harcourt

Industrial activities in Port Harcourt, Rivers State, South South Nigeria, generate significant atmospheric pollutants that pose health risks to surrounding communities, yet affordable real-time environmental monitoring infrastructure remains limited. This project implemented a low-cost Internet of Things environmental monitoring node capable of measuring particulate matter (PM2.5 and PM10), carbon monoxide, nitrogen dioxide, ambient temperature, and relative humidity. The node was built around an ESP32 microcontroller with onboard WiFi connectivity, using a PMS5003 laser particle counter, MQ-7 and MQ-135 gas sensors, and a DHT22 temperature-humidity sensor. Sensor data were published to a ThingSpeak IoT cloud platform via MQTT protocol at 60-second intervals. A custom web dashboard allowed visualisation of real-time and historical data with threshold-based alert emails. The node was calibrated against a reference-grade TSI DustTrak analyser at the University of Port Harcourt Environmental Engineering Laboratory. Calibration results showed a root mean square error of 4.7 micrograms per cubic metre for PM2.5 and 6.1 micrograms per cubic metre for PM10. CO sensor accuracy was within plus or minus 8 percent of reference values. Total component cost was 18,400 naira, approximately 12 percent of the cost of commercial equivalents. The study identifies low sensor cross-sensitivity and power stability under tropical humidity as areas requiring further refinement. Deployment of a six-node monitoring grid around the Trans-Amadi industrial estate is recommended as the next phase.

Keywords: IoT environmental monitoring, air quality, Port Harcourt, ESP32, particulate matter