2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
METABOLIC ANALYSIS OF IN-SITU WORK PERFROMED IN A
CANADIAN DEEP MINE
1 Maté, J., 1 G.P. Kenny, 1 F. D. Beaulieu, 2 S. Hardcastle, 1 O. Jay, 1 F.D.Reardon
1 University of Ottawa, School of Human Kinetics, 1 Laboratory of Human Bioenergetics and
Environmental Physiology Ottawa, Ontario, Canada; and, 2 Natural Resources Canada’s
Mining and Mineral Sciences Laboratories Sudbury, Ontario, Canada.
Contact Person: freardon@uottawa.ca
Higher ambient temperatures are being experienced by mining personnel as current practices
allow for mining to occur at greater depths. The American Conference of Governmental
Industrial Hygienists published Threshold Limit Values ® that are based on the wet bulb globe
temperature (WBGT). Accompanying the high variability in the jobs performed and also in
the workers body size, body composition, and physical efficiency, there is a need to account
for these variables in establishing “best practice” work standards for deep Canadian mines.
The purpose of this investigation was to establish the metabolic energy expenditure under
typical mining conditions for selected common mining jobs. The results are presented from
the first phase of a multi phase project.
Six common in-situ mining jobs were evaluated according to a five level work intensity scale
(ISO 7243), with concurrent deep tissue (core) and skin temperature measurements. These
six jobs were categorized into three groups according to similar metabolic energy
expenditures for statistical analysis. These groups consisted of: Bolting and Scooptram
(Group BOL), Production drill, Conventional Mining, and Shotcrete (Group PRO), and
Services (Group SER) Average dry bulb, relative humidity, and an indirect WBGT were
Group BOL (26.1 ± 2.5 °C, 64.0 ± 18.4 %, 23.5 ± 2.8°C) Group PRO (26.4 ± 2.2°C, 61.3 ±
20.5 %, 21.7 ± 1.9°C) and Group SER (24.0 ±4.6°C, 55.9 ± 25.2 %, 25.7 ± 1.3) respectively.
Average subject characteristics were: 40 yrs, 1.70 ± 0.31 m, 83.6 ± 20.3 kg, 20.6 ± 7.3 %
body fat, and 1.96 ± 0.39 BSA. Significant differences were observed between all three job
groups (Group BOL, PRO, and SER) at intensity levels of 2 (P = 0.033), 4 (P = 0.033), and 5
(P = 0.047). Means and standard deviations of metabolic energy expenditures measured for
groups BOL, PRO, and SER were 284.8 ± 91.6 W, 602.0 ± 194.5 W, and 735.9 ± 199.5
W accordingly. Maximum metabolic energy expenditures observed in each group were
1104.1 W, 958.6 W, and 1080.4 W BOL, PRO SER respectively. The proportion of work
time spent using upper body versus lower body movements differed significantly amongst the
three groups (P < 0.001). These were 90 % verus 75 % for BOL, 83 % versus 30 % for PRO
and 84 % versus 53 % for SER for upper versus lower body movements respectively.
Changes from baseline to end of work shift deep tissue temperature were Group BOL 0.4 ±
0.2°C, Group PRO 0.3 ± 0.2°C, and Group SER 0.2 ± 0.2°C. Differences in the change were
found to be significant (P < 0.001) in all groups. Change in mean skin temperature
from baseline to end of work shift were Group BOL 1.4 ± 1.5°C, Group PRO 1.4 ± 0.8°C, and
Group SER 2.0 ± 1.7°C. In groups PRO (P < 0.001) and SER (P = 0.034) significant
differences were identified.These findings show that metabolic energy expenditure appeared
to be largely dependent on the type of mining job. Further, under these environmental
conditions the miners do not appear to be in a state of uncompensated heat stress. Miners
may be at a greater risk of heat stress when exposed to higher ambient temperature and
humidity conditions when performing the same work intensity.
ACKNOWLEDGEMENT
The authors gratefully acknowledge Deep Mining Research Consortium (DMRC) financial
support and cooperation in the research leading to this publication.
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