A Field Evaluation of the Physiological Demands of Miners in Canada's Deep Mechanized Mines

This study was conducted to evaluate the physical/mechanical characteristics of typical selected mining tasks and the energy expenditure required for their performance. The study comprised two phases designed to monitor and record the typical activities that miners perform and to measure the metabolic energy expenditure and thermal responses during the performance of these activities under a non-heat stress environmental condition (ambient air temperature of 25.8 degrees C and 61% relative humidity with a wet bulb globe temperature (WBGT) of 22.0 degrees C). Six common mining jobs were evaluated in 36 miners: (1) production drilling (jumbo drill) (n = 3), (2) production ore transportation (load-haul dump vehicle) (n = 4), (3) manual bolting (n = 9), (4) manual shotcrete (wet/dry) (n = 3), (5) general services (n = 8) and, (6) conventional mining (long-hole drill) (n = 9). The time/motion analysis involved the on-site monitoring, video recording, and mechanical characterization of the different jobs. During the second trial, continuous measurement of oxygen consumption was performed with a portable metabolic system. Core (ingestible capsule) and skin temperatures (dermal patches) were recorded continuously using a wireless integrated physiological monitoring system. We found that general services and manual bolting demonstrated the highest mean energy expenditure (331 +/- 98 and 290 +/- 95 W, respectively) as well as the highest peak work rates (513 and 529 W, respectively). In contrast, the lowest mean rate of energy expenditure was measured in conventional mining (221 +/- 44 W) and manual shotcrete (187 +/- 77 W) with a corresponding peak rate of 295 and 276 W, respectively. The low rate of energy expenditure recorded for manual shotcrete was paralleled by the lowest work to rest ratio (1.8: 1). While we found that production drilling had a moderate rate of energy expenditure (271 +/- 11 W), it was associated with the highest work to rest ratio (6.7:1) Despite the large inter-variability in energy expenditure and work intervals among jobs, only small differences in average core temperature (average ranged between 37.20 +/- 0.22 to 37.42 +/- 0.18 degrees C) were measured. We found a high level of variability in the duration and intensity of tasks performed within each mining job. This was paralleled by a large variation in the work to rest allocation and mean energy expenditure over the course of the work shift.