Development and experimental evaluation of an IoT-based closed-loop system for PM2.5 monitoring and automated electrical ionization actuation
Abstract
Fine particulate matter (PM2.5) remains a major environmental health concern in Thailand and motivates the development of monitoring systems that can support localized, automated responses. This research presents and experimentally evaluates Cleara-Air , an integrated Internet of Things (IoT) and Web-GIS closed-loop system for real-time particulate-matter monitoring and threshold-based electrical ionization actuation. The system integrates an ESP32 microcontroller, a Sensirion SPS30 particulate sensor, a 4-channel 5V relay, a 220V AC ventilation fan, and a carbon-brush negative-anion generator, with PostgreSQL-based data storage and a responsive Web Map Application. The controller continuously acquires particulate measurements and uses 37.5 μg/m 3 as an operational PM2.5 set-point when the measured concentration exceeds this value, the relay activates the fan and ionization module, and the actuators are deactivated when the concentration subsequently falls below the set-point. The integrated workflow was evaluated through 15 repeated closed-room functional trials in which particulate concentrations were intentionally elevated near the SPS30 sensor. The evaluation examined threshold detection, actuator activation and deactivation, 15-s data transmission, database logging, and Web-GIS status visualization. The repeated tests demonstrated that the programmed sensing-processing-communication-actuation sequence operated as intended under the tested conditions, providing original experimental evidence of the functional performance of the integrated closed-loop architecture. The study evaluates system functionality rather than PM2.5 removal efficacy quantitative treatment-vs.-control experiments, reference-grade sensor calibration, and direct ozone measurements remain necessary before claims regarding mitigation effectiveness or operational safety can be made. The results establish Cleara-Air as an experimentally evaluated prototype framework for integrating real-time environmental sensing, automated control, and geospatial information delivery.