The World Health Organization (WHO) and the World Meteorological Organization (WMO) have jointly issued a stark warning about the growing threat of heat stress on workers worldwide, releasing a new technical guidance report aimed at protecting laborers as climate change drives global temperatures higher. The report, published August 22, 2025, calls for urgent government and employer action to address the increasing health and economic impacts of extreme heat on the global workforce.
The joint publication, titled Climate Change and Workplace Heat Stress, highlights that 2024 was the hottest year ever recorded, with heatwaves affecting every region and work sector. Temperatures in many areas surpassed 40 degrees Celsius for extended periods, with some locations recording temperatures above 50 degrees. The report finds that rising heat levels are no longer confined to traditionally hot climates and are now placing a broad spectrum of workers at risk, from outdoor laborers in agriculture and construction to indoor staff in inadequately ventilated environments.
Data included in the report, compiled from over five decades of research, reveal that more than 2.4 billion workers are now exposed to excessive heat annually. This exposure is directly linked to an estimated 22.85 million occupational injuries each year, in addition to nearly 19,000 work-related fatalities. Productivity is also being impacted, with the report noting a 2 to 3 percent decline in output for every degree Celsius rise in temperature above 20 degrees.
The most vulnerable groups include workers in low-income countries, those performing manual labor, and populations with limited access to healthcare and workplace protections. Health consequences linked to prolonged heat exposure range from dehydration and heatstroke to kidney disease and cardiovascular strain. In extreme cases, prolonged exposure can lead to long-term disability or death. In response to these findings, the WHO and WMO are urging governments, employers, trade unions, and occupational health authorities to implement occupational heat-health action plans.
Action plans recommended for occupational heat protection
These plans should include early warning systems, hydration monitoring, first-aid training, and infrastructure upgrades such as shaded rest areas and access to drinking water. Employers are also advised to reschedule work shifts to cooler hours, rotate strenuous tasks, and ensure employees have adequate rest periods during high-temperature conditions. The report further recommends the use of practical tools such as urine color charts and body weight monitoring to detect dehydration.
A buddy system to spot early symptoms of heat-related illness and clear referral pathways to medical care are also part of the guidance. Health professionals and emergency responders should receive specific training to recognize and treat heat-induced conditions, particularly during prolonged heatwaves. Dr. Jeremy Farrar, Assistant Director-General at WHO, stated that heat stress is already severely affecting workers’ health and livelihoods around the world.
Tools and training key to preventing heat stroke and injury
He emphasized the importance of implementing evidence-based, practical solutions to reduce harm and inequality in the workplace. WMO Deputy Secretary-General Ko Barrett noted that protecting workers from extreme heat is critical not only for health but also for sustaining economic productivity in a warming world. The Wellcome Trust, responding to the report, echoed concerns about the wider public health implications of rising temperatures. The organization highlighted that extreme heat also contributes to complications such as cardiovascular disease, pregnancy-related issues, kidney failure, and poor mental health.
It called on policymakers to support immediate occupational safety measures alongside long-term investments in climate resilience. As heatwaves grow more intense and frequent, the WHO and WMO are calling for coordinated global action to safeguard worker health, ensure continuity in essential sectors, and mitigate the long-term economic damage associated with climate-driven heat stress. The report underlines that the risks are measurable, the solutions are available, and the time to act is now.