Physiological responses to heat stress in rice transplanting workers in Northeast India and work-rest schedule recommendations

Abstract

Background

Heat stress has a detrimental impact on workers’ health, resulting in reduced workplace productivity and an increase in heat-related illnesses and fatalities. Manual paddy transplantation in Northeast India (NEI), performed under high heat and humidity, requires significant physical effort, leading to fatigue. Implementing work-rest schedules is a practical approach to minimize heat stress.

Objective

This study aimed to investigate the efficacy of work-rest schedules for agricultural workers in Northeast India for manual paddy transplanting at various Wet-bulb globe temperature (WBGT) settings.

Method

Fourteen participants were selected to assess thermal and physiological stress during rice transplanting (summer crop) under WBGT conditions of 27–32 °C. Participants were given rest from work once their oral body temperature increased by 0.5 °C. Work time was defined as the period leading to this increase, while rest time was the duration needed for oral temperature to normalize, based on ISO 7933 thresholds.

Results

Oral temperature increased by 0.5 °C after 65 min of work, requiring 15 min to normalize at 27–28 °C. Recommended work-rest durations were 65 min and 15 min, respectively. At 29–30 °C and 31–32 °C, work-rest durations were 50 and 20 min, and 35 and 22 min, respectively. These findings provide a critical foundation for future research on climate-resilient occupational health strategies, particularly in regions vulnerable to rising temperatures due to global warming.

Conclusions

Agricultural workers in Northeast India face heat stress during manual paddy transplantation. It is recommended that customized work-rest schedules be implemented based on WBGT conditions to enhance safety and productivity. Regular monitoring of oral temperature and heart rate is essential to prevent heat-related health issues.