Estimation of real-time PM exposure and associated health risk of HEMM operators using low-cost sensors in a highly mechanised opencast coal mine

Abstract

The working environment of the operators of heavy earth moving machineries (HEMMs) expose them to high airborne particulate matter (PM) concentration as a part of their occupation. Using a set of low-cost sensors, the present study investigated the in-cabin PM exposure of dumper, shovel and drill machine operators and compared it with the cabin outside PM concentration in a large opencast mine where a large number of HEMMs are deployed. The results revealed that the drill operators were exposed to the highest in-cabin PM concentration (PM₁ = 190.98 ± 30.3 µg m⁻³, PM_2.5 = 281 ± 52.85 µg m⁻³, PM₁₀ = 1475.23 ± 915.42 µg m⁻³) followed by the exposures of shovel (PM₁ = 45.62 ± 24.28 µg m⁻³, PM_2.5 = 97.85 ± 51.10 µg m⁻³, PM₁₀ = 354.38 ± 219.69 µg m⁻³) and dumper operators (PM₁ = 42.08 ± 18.25 µg m⁻³, PM_2.5 = 90.38 ± 44.55 µg m⁻³, PM₁₀ = 331.05 ± 225.65 µg m⁻³). The exposure in the evening shift was 10% higher than exposure during the morning shift. The in-cabin PM concentrations while the dumper travelled on main haul road were ~ 2 times of the corresponding values when it travelled on the internal haul road. In addition to the outside concentration, the in-cabin PM levels are influenced by cabin ventilation (AC vs. non-AC), structural leakage, and door/window operation. AC cabins could reduce the PM exposure up to 40% (10% for non-AC cabins) than ambient mine environments. GLM explained 65–89% of PM concentration variability, with HEMM type and meteorological parameters as significant predictors. The health risk assessment indicates that all operators are exposed to non-carcinogenic health risks, as the Risk Quotient (RQ) values for each exceed the threshold of 1 (RQ > 1). Notably, the drill operator is subjected to the highest non-carcinogenic risk, with an RQ value of 8. While, the Excess Lifetime Cancer Risk (ELCR) assessment for PM_2.5 exposure reveals potential carcinogenic risks among operators in two age groups. For the 18-year age group, the ELCR values range from 6.15 × 10⁻⁴ to 1.92 × 10⁻³, whereas for the 21 years and above age group, the values range from 5.13 × 10⁻⁴ to 1.60 × 10⁻³, indicating elevated cancer risk among 18 + age group of operators. This research highlights the occupational health risk of the HEMM operators working in opencast mines and important role of low-cost sensors in real-time PM exposure assessment in mining environments.