Geneva, 22 August 2025
Key messages
- The frequency and intensity of extreme heat events have risen sharply, increasing risks for both outdoor and indoor workers, the World Meteorology Organization (WMO) reports.
- Worker productivity drops by 2–3% for every degree above 20°C.
- Health risks include heatstroke, dehydration, kidney dysfunction, and neurological disorders, all of which hinder long-term health and economic security.
- Approximately half the global population suffers adverse consequences of high temperatures.
As climate change drives more frequent and intense heatwaves, many workers who are regularly exposed to dangerous heat conditions are already feeling the health impacts of rising temperatures, in particular, manual workers in sectors such as agriculture, construction and fisheries. Increasing heat episodes are also leading to health issues for vulnerable populations in developing countries, such as children, older adults and low-income populations.
The report and technical guidance draws on five decades of research and evidence, highlighting that the health and productivity of workers are severely impacted by rising temperatures. WMO reports that 2024 was the hottest year on record. Daytime temperatures of more than 40°C and even above 50°C are becoming increasingly common, a clear indication that immediate action is needed to address the worsening impact of heat stress on workers worldwide.
Source – WMO