245 Administration (MSHA), a US federal agency, has recommended the use of CPDM. However, these samplers are several times expensive, weight more than 2kgs and are bulky to carry by miners during the working. Recently, compact, portable, and miniature sensors that can measure real-time dust concentration are being increasingly used across different indoor and outdoor environments (Dubey et al., 2024). These devices are several times less expensive in comparison to the CPDM and provide simultaneous readings of different sized particle mass concentrations. While low-cost sensors offer a more affordable and portable solution for air quality monitoring, their lower accuracy compared to reference-grade instruments highlight a trade-off that needs to be managed. Before deploying the sensor, the standard practice is to calibrate sensors along with reference instruments at the desired field of installation (Badura et al., 2018). Calibration is the process of adjusting the sensor's output to match a reference standard to ensure accurate data over time. Researchers have performed extensive site-specific calibration experiment and deployed sensors for real-time mobile monitoring of pollution concentration along haul roads in large sulfide open-pit (Zafra-Pérez et al., 2023a). Sensor was mounted on unmanned aerial vehicle for measuring airborne PM levels inside and around the surface mine to assess the air quality within and around the mine during different mining operation (Zafra-Pérez et al., 2023b). In order to investigate the comprehensive performance and evaluate the suitability of LCPMS for occupational exposure, LCPMS were exposed to uncontrolled dust concentrations prevailing at surface coal mine (Penchala et al., 2025). Exposure of heavy earth moving machinery operators in large coal mine was assessed by installing LCPMS inside the operators cabin close to the breathing zone (Pradhan et al., 2025). Based on the previous research on application of LCPMS in the mining environment, this study deployed multiple sensors at different benches across the depth of the surface iron ore mine. Further, LCPMS was coupled with an unmanned aerial vehicle (UAV) for assessing the vertical transport of PM generated from several in-pit mining operations in the coal mine. 2. MATERIALS AND METHOD 2.1 Instrumentation The OPC N3 sensor (Make: Alphasense, United Kingdom) is a small (75 mm x 60 mm x 6 5mm) and light (105 g) optical particle counter that can identify particles with diameters ranging from 0.38 to 40 µm in 24 bin sizes (Figure 1). The particles are counted using an elliptical mirror and a dual-element photo-detector.
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