Thermal stress in North Western Australian iron ore mining staff Authors

Introduction: Demand for Australian mined iron ore has increased employment within this sector thus exposing increased numbers of workers to the harsh Australian climate. This study examined the influence of hot (>30C WBGT) environmental temperatures, consistent with working in North Western Australia, on iron ore mining staff. Methods: Core temperature, hydration status, perceived exertion, mood and fatigue state were measured in 77 participants at three time points (pre-, mid-, and post-shift) during a normal a 12-hour shift at an open cut iron ore mining/processing site (N= 31; Site1) and an iron ore processing/shipping site (N= 46; Site2). Results: A significant effect for time was observed for core temperature with greater mean core temperatures measured mid(37.5 ± 0.4C) and post-shift (37.6 ± 0.3C) compared with pre-shift values (37.0 ± 0.5C). All mean core temperature measures were below ISO7933 thresholds (38C) for thermal safety. Mean hydration measures (Urine Specific Gravity; USG) were greater at Site1 (1.029 ± 0.006) compared with Site2 (1.021 ± 0.007). Furthermore, both preand post-shift measures from Site1 and post-shift measures from Site2 were greater than the threshold for dehydration (USG = 1.020). No differences were observed for mood or perceived exertion over time; however, measures of fatigue state were greater post-shift compared with preand midshift values for both sites. Conclusions: Our findings indicate that while the majority of mine workers in North Western Australia are able to regulate work-rate in hot environments to maintain core temperatures below ISO safety guidelines, 22% of workers reached or exceeded the safety guidelines, warranting further investigation. Furthermore, hydration practices, especially when off-work, appear inadequate and could endanger health and safety.