Thermal Exposure and Related Heat Illness Symptoms among Workers in Mara Gold Mines

Abstract

Background: Working in humid and hot environment expresses the unique challenges to occupational health and safety in tropical countries. Tanzania being in the region experiences high ambient temperature that can exceed 30°C. The high temperature expose mining workers to heat related injury and illness and hence reduce productivity. Study Objective: This study was undertaken to assess heat stress exposure and associated heat illness symptoms among gold mine workers at Mara region. Materials and Methods: A cross section study was conducted where the Similar Exposure Groups (SEG) of study participants were selected based on their risk to extreme heat environment. The Wet Bulb Globe Temperature (WBGT) index was used to assess the heat load while the change in core body temperature, blood pressure and pulse rate of miners presented the heat strain indicator. Data were analyzed using IBM SPSS software version 20. Chi-square test and Pearson correlation were used as a measure of association, while t-test and one way ANOVA were used to check the significant differences between the variables. The p values of < 0.05 were considered significant. Results: Results showed that the averaged wet bulb globe temperature at the mining workplace 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. Moreover high body temperature and hot and dry skin were the highly reported heat illness symptoms among miners. Open cut mine workers were under much greater heat strain than underground mine workers with the mean core body temperatures of 38.4 ± 0.5°C and 37.3 ± 0.5°C respectively (p-value = 0.000). Approximately 80% of workers in open cut miners indicated high core body temperature above ISO 7933 threshold of 38.0°C for safety. Majority of workers under contractor were found to consume less water prior to work shift commencement. Conclusion and recommendation: Occupational setting at the mining area presents the potential exposure to thermal condition that can contribute to heat illness symptoms. Therefore effective strategies like hydration program and breaks must be implemented to enhance workers safety in mines.