Assessing implications of occupational heat stress on the physiological and productive attributes of small-scale foundry workers in Northern India

<b>Background:</b> Work operations involving intensive physical activities under hot stressful workplaces may impose substantial heat stress on the employed workforce, particularly in underdeveloped countries. <b>Objective:</b> The present study analysed occupational heat stress and its effect on workers' well-being and productivity under distinct work environments in small-scale foundries in Northern India. <b>Methods:</b> Several dominant heat indices were used for evaluating the occupational heat risk exposure among foundry workers. The workers' thermal perception was examined using the Heat Strain Score Index (HSSI) subjective assessment. Further, physiological parameters were recorded to evaluate the heat strain endured by workers. Work productivity losses under thermal work conditions were also estimated. <b>Results:</b> Higher occupational heat risk exposures were associated with furnace (Wet Bulb Globe Temperature (WBGT): 33.54°C (0.784), Tropical Summer Index (TSI): 38.82°C (3.273)) and metal pouring (WBGT: 32.93°C (0.663), TSI: 38.47°C (1.441)) sections, with indices exceeding permissible limits. From subjective assessment, 90% and 86.7% of workers in furnace and metal pouring section perceived higher thermal discomfort. A rise in workers' physiological attributes was observed under sections involving high radiant heat exposure and intensive physical workload. Strong relations were observed among WBGT and HSSI indices (r = 0.831), indicating good agreement between quantitative and subjective assessments. With the exception of systolic and diastolic blood pressure, positive associations were seen among WBGT and monitored physiological variables (core body temperature (r = 0.705), skin temperature (r = 0.670), and heart rate (r = 0.353)). The productivity model estimated work performance losses associated with metal pouring (53%), furnace (43.24%), and fettling (37.61%) work sections under these foundry industries. <b>Conclusion:</b> Research findings indicated the need for sanative control measures based on ameliorating prevalent thermal work conditions found in this study. This study suggests that industrial/occupational health practitioners should analyse small-scale foundry industries for prevalent heat stress issues and develop new guidelines/standards to improve existing thermal work conditions in these industries.