Assessment of occupational heat stress in mechanised underground metalliferous mines in India: Implications for ventilation and regulatory policy

Occupational heat stress in underground mines is a growing global concern. Miners working in such hot and humid conditions face a significant occupational health risk, affecting their health and productivity. Therefore, appropriate heat-stress management techniques are necessary. This study presents a systematic field monitoring of thermal environmental conditions in two mechanised underground metalliferous mines in India. Field measurements revealed high temperatures, elevated relative humidity, and inadequate airflow across various working areas in the investigated mines. The obtained parameters were also systematically compared against thermal exposure limits prescribed by national and international regulatory authorities and occupational health and safety organisations. The wet bulb globe temperature and effective temperature measurements showed repeated exceedances of the threshold limit. However, the wet bulb temperature values, assessed according to the Indian Standard, indicated that the miners were not exposed to heat stress. These findings collectively advocate adopting a comprehensive thermal index as the basis for mandatory heat-stress monitoring and call upon policymakers, statutory bodies and mining operators to reform existing regulatory frameworks to ensure scientifically robust and operationally effective heat-stress management in Indian underground metalliferous mines.