IOT-BASED OUTDOOR AIR QUALITY MONITORING IN CAMPUS ENVIRONMENTS: AN APPLICATION-ORIENTED STUDY USING LOW-COST SENSORS

Abstract

Outdoor air quality has a significant impact on the health and comfort of academic environments, particularly on university campuses where students and faculty spend considerable time. The conditions in the indoor lecture building are greatly influenced by outdoor air quality. Putting environmental air quality in terms of health will help show the risk from pollution. This study introduces a simple and affordable solar-powered IoT air quality monitoring system, which was carefully designed, tested in the lab, and then deployed for a certain period on a university rooftop. The system consisted of an ESP32 microcontroller installed with sensors for temperature, humidity, CO₂, CO, NO₂, and PM₂.₅. A 20-WP solar panel, along with a rechargeable battery, ensures it runs independently. Sensor characterization was performed using manufacturer datasheets, using regression models and reference data to improve accuracy. Environmental measurements were recorded every 7 minutes, which  generates 6,000 data in average during the study period every month. Real-time data transmission to Google Sheets enabled continuous monitoring, revealing hourly pollutant fluctuations linked to campus activity patterns. Analysing data reported in real time, the air quality parameters detected hourly variations in concentrations and the impact of human activity on air quality by analysing real-time reported data. The results showed that CO was rated between 260 and 290 ppm, CO₂ shot up past 1500 ppm during busy hours, NO₂ spikes reached over 60 ppm in a few cases, and PM₂. ₅ reaching up to 20 µg/m³. These findings show how pollution levels fluctuate with campus activity, underscoring the need for continuous air quality monitoring. In addition, the results confirm that the proposed system successfully demonstrated continuous environmental monitoring under field conditions.