The World Health Organization and the World Meteorological Organization have jointly released a new technical report and guidance to address the growing crisis of workplace heat stress. The document builds on decades of evidence and highlights practical measures to protect workers from mounting risks as climate change intensifies.
Important Findings
The guidance draws attention to the latest International Labor Organization findings. Over 2 billion workers worldwide are exposed to excessive heat. This leads to millions of occupational injuries annually. The guidance aligns with the recognition of safe work environments as fundamental rights that require coordinated international commitment and enforcement.
Both organizations stressed that heatwaves are becoming increasingly severe and frequent. Global temperatures are rising sharply, with recent years recording unprecedented heat. In many regions, daily temperatures above 40 degrees Celsius, and sometimes surpassing 40 degrees, have become more common, creating serious risks for outdoor and indoor workers alike.
Among the most vulnerable are those in agriculture, construction, and fisheries who perform physically demanding work outdoors. Indoor workers exposed to hot processes, such as those in greenhouses, mines, and factories with poor ventilation, also face heightened risks of illness and reduced performance under dangerous environmental conditions.
Health consequences of heat stress are significant. Effects range from dehydration and fainting to kidney problems, neurological disturbances, and heat exhaustion. In severe cases, heat stroke occurs, which is life-threatening. Evidence indicates that more than 35 percent of workers frequently exposed to high temperatures suffer from heat-related illnesses.
The economic consequences are equally alarming. Productivity is known to decline by 2 to 3 percent for each 1 degree Celsius rise in wet bulb globe temperature above 20 degrees. Research shows that nearly 30 percent of workers frequently exposed to heat report substantial productivity losses. This creates serious challenges for industries worldwide.
Scientific definitions and thresholds are central to the report. Workplace heat stress occurs and can be measured when heat from metabolism, environment, and clothing exceeds the capacity of the body to cool itself. Wet bulb globe temperature provides the most reliable measure because it incorporates humidity, solar radiation, and wind, unlike air temperature alone.
The report specifically underlines that core body temperature during an 8-hour work shift should not go above 38 degrees Celsius for safe operations. Higher sustained body temperatures drastically increase risks. Heat fatigue, rash, cramps, and syncope signal early warning, while heat exhaustion and heat stroke represent severe and potentially fatal stages.
Key Recommendations
Both organizations also emphasized the importance of Occupational Heat Action Programmes. These programs must be tailored to specific local conditions, accounting for weather, occupation, and worker vulnerability. One-size solutions are inadequate, and context-sensitive measures are required to ensure effective protection and sustainable long-term outcomes.
The recommendations highlight several priorities, including policies that safeguard high-risk groups such as older employees, pregnant workers, those with chronic diseases, and international migrant workers. These groups are often less protected, less acclimatized, or more vulnerable to the physical impacts of prolonged heat exposure and heavy workloads.
WHO and WMO also urge governments and employers to improve education. Training health professionals, first responders, and supervisors to recognize and treat heat illness is crucial. Early identification prevents fatalities, yet misdiagnosis remains common, often delaying effective care for affected individuals in both urban and rural environments.
Stakeholder participation is another important component. Effective implementation requires collaboration between employers, unions, health agencies, and workers themselves. This approach ensures that interventions are practical, culturally appropriate, and economically feasible. It also strengthens trust and accountability while promoting long-term sustainability.
The report outlines the need for affordable and environmentally sustainable interventions. Cooling systems, improved ventilation, and better workplace design are essential but must be scaled in ways that minimize environmental burdens. Innovative solutions, such as wearable sensors or workload scheduling based on heat indices, can further enhance worker safety.
Note that the guidance provides a comprehensive blueprint for protecting workers in a warming world. It combines scientific thresholds with practical measures and emphasizes prevention, awareness, and cooperation. The recommendations are intended to safeguard lives, protect economies, and uphold the dignity of labor in an era of climate challenges.
FURTHER READING AND REFERENCE
- World Meteorological Organization and World Health Organization. 2025. Climate Change and Workplace Heat Stress Technical Report and Guidance. World Meteorological Organization and World Health Organization. ISBN: 978-92-63-11376-4. Available online