UN Warns Rising Heat Stress Threatens Workers' Health Globally

Farmers in rural Madagasca

Extreme heat is becoming one of the biggest threats to workers' health and livelihoods, the World Health Organization (WHO) and World Meteorological Organization (WMO) warned on Friday.

The joint report, Climate Change and Workplace Heat Stress, underscores the growing risks as climate change fuels longer, more frequent, and more intense heatwaves.

The report highlights that workers in agriculture, construction, and fisheries are already experiencing the severe effects of dangerous temperatures. It also points out that vulnerable groups in developing countries—such as children, older adults, and low-income communities—are increasingly at risk.

“Heat stress is already harming the health and livelihoods of billions of workers, especially in the most vulnerable communities,” said Dr. Jeremy Farrar, WHO Assistant Director-General for Health Promotion, Disease Prevention, and Care. “This new guidance provides practical, evidence-based solutions to protect lives, reduce inequality, and build more resilient workforces in a warming world,” he added.

Drawing from five decades of research, the report shows how rising temperatures are negatively impacting both health and productivity.

WMO confirmed that 2024 was the hottest year on record, with temperatures reaching 1.55°C above pre-industrial levels. Daytime highs above 40°C have become commonplace, and in some areas, temperatures are even exceeding 50°C.

“Occupational heat stress has become a global challenge, no longer confined to countries near the equator, as highlighted by the recent heatwave in Europe,” said Ko Barrett, WMO Deputy Secretary-General. “Protecting workers from extreme heat is not just a health imperative but an economic necessity.”

The report outlines the serious consequences of extreme heat on workers. It finds that worker productivity drops by 2 to 3 percent for every degree above 20°C.

The health impacts are wide-ranging, including heatstroke, dehydration, kidney dysfunction, and neurological disorders. Overall, nearly half of the world’s population is already suffering from the effects of extreme heat.

The WHO and WMO’s guidance calls for urgent occupational heat action plans tailored to specific industries and regions. These plans include several recommendations:

Develop targeted occupational heat-health policies based on local weather conditions and workforce vulnerabilities.

Prioritize protections for middle-aged and older workers, those with chronic health conditions, and individuals with lower physical fitness.

Train health professionals, employers, and workers to recognize and treat heat stress, which is often misdiagnosed.

Involve workers, unions, and local authorities in shaping heat-health strategies.

Promote affordable, sustainable, and scalable solutions, alongside innovation and new technologies.

Strengthen research and monitoring to ensure these measures remain effective.

The guidance builds on International Labour Organization (ILO) findings, which report that more than 2.4 billion workers are exposed to excessive heat globally, leading to over 22.85 million occupational injuries each year.

“This report represents a critical milestone in our collective response to the growing threat of extreme heat in the world of work,” said Joaquim Pintado Nunes, ILO Chief of Occupational Safety and Health and the Working Environment.

“Aligned with the ILO’s mandate to promote safe and healthy working environments as a fundamental right, it offers robust, evidence-based guidance to help governments, employers, and workers confront the escalating risks of climate change,” he added.

Both UN agencies stress that addressing heat stress is essential for safeguarding lives, livelihoods, and economies. The guidance supports the UN Sustainable Development Goals (SDGs) and urges immediate action to protect vulnerable workers, reduce poverty, and promote sustainable growth.

Urgent and coordinated action is no longer optional; it is essential, the report concludes.