Thermal Exposure and Heat Illness Symptoms among Workers in Mara Gold Mine, Tanzania

BACKGROUND: Working in a humid and hot environment creates challenges to occupational health and safety in tropical countries. Being in the region, Tanzania can experiences more than 30°C ambient temperature, which exposes miners to heat-related injury and illness. OBJECTIVES: This study was conducted to assess heat stress exposure and associated heat illness symptoms among gold mine workers in the Mara region. METHODS: A cross-sectional study was conducted among 60 miners from four Similar Exposure Groups based on risk to extreme heat environment. The WBGT index was used to assess the heat load while the miners’ physiological condition explained the heat strain indicator. Data was analyzed using SPSS 20. Chi-square was used to differentiate proportion of miners with heat illness symptoms in different categories. Pearson correlation was used to determine association between environmental measures and change in physiological conditions of the miners. Independent t-test and ANOVA were used to assess differences between numerical data among groups. A p ≤ 0.05 at 95% confidence was considered to be statistically significant. FINDINGS: The recorded average WBGT at the mining site was within the ACGIH TLV of 28.5°C, however, 78.4% of underground miners and 69.6% of open cut miners reported to have moderate heat illness. High body temperature and hot and dry skin were the most frequently reported heat illness symptoms. The mean core body temperatures of miners in open cut and underground were 38.4 ± 0.5°C and 37.3 ± 0.5°C respectively. Approximately 80% of miners in open cut indicated higher core body temperature above ISO 7933 threshold of 38.0°C for safety. The majority of workers under contract didn’t drink water prior to work shift commencement. CONCLUSIONS: The occupational setting at the mining area presents the potential exposure to a thermal condition that can contribute to heat illness symptoms. Effective strategies must be implemented to enhance workers’ safety.