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WHO, WMO issue new report and guidance to protect workers from increasing heat stress
22 August 2025, Geneva –The World Health Organization (WHO) and the World Meteorological Organization (WMO) have published a new joint report and guidance highlighting the growing global health challenges posed by extreme heat on workers.
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.
“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, Health Promotion, Disease Prevention and Care. “This new guidance offers practical, evidence-based solutions to protect lives, reduce inequality, and build more resilient workforces in a warming world.”
The new report and technical guidance, entitled Climate change and workplace heat stress 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.
“Occupational heat stress has become a global societal challenge, which is no longer confined to countries located close to equator – as highlighted by the recent heatwave in Europe,” said WMO Deputy Secretary-General Ko Barrett. “Protection of workers from extreme heat is not just a health imperative but an economic necessity.”
Key findings
The report and guidance outline key issues related with health impacts of extreme heat.
- The frequency and intensity of extreme heat events have risen sharply, increasing risks for both outdoor and indoor workers.
- 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.
To tackle these challenges, the report calls for the implementation of occupational heat action plans, tailored to specific industries and regions, and developed in collaboration with employers, workers, unions, and public health experts.
Recommended actions
The guidance lays out a clear path for governments, employers, and health authorities to mitigate the growing risks of extreme heat on working populations. The recommended actions include:
- Develop occupational heat-health policies with tailored plans and advisories that consider local weather patterns, specific jobs, and worker vulnerabilities;
- Focus on vulnerable populations with special attention given to middle-aged and older workers, individuals with chronic health conditions, and those with lower physical fitness who can be more susceptible to the effects of heat stress;
- Education and awareness raising for first responders, health professionals, employers, and workers to recognize and properly treat heat stress symptoms, which are often misdiagnosed;
- Engage all stakeholders from workers and trade unions to health experts and local authorities in the co-creation of heat-health strategies that are locally relevant and widely supported.
- Design solutions that are not only effective but also practical, affordable and environmentally sustainable, ensuring policies can be implemented at scale.
- Embrace innovation by adopting technologies that can help safeguard health while maintaining productivity.
- Support further research and evaluation to strengthen the effectiveness of occupational heat-health measures and ensure maximum protection for workers worldwide.
The report and technical guidance by WHO and WMO complement the findings of the recent International Labour Organization (ILO) reports, which highlight that more than 2.4 billion workers are exposed to excessive heat globally, resulting in more than 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’s 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. Together with WHO and WMO, we call for urgent, coordinated action to safeguard the health, safety and dignity of the more than 2.4 billion workers exposed to excessive heat worldwide.”
Call to action
This guidance serves as a critical resource for policymakers, public health officials, and employers in mitigating the escalating impact of workplace heat stress. It aligns with key United Nations Sustainable Development Goals, calling for decisive actions that protect vulnerable workers, reduce poverty, and promote sustainable economic growth. Immediate implementation of policies and programmes that safeguard worker health and productivity in the face of climate change is essential.
In the context of accelerating climate crisis, this guidance serves as a vital tool to help countries respond decisively, protecting lives, livelihoods and economies from the growing threat of extreme heat.
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Professor Francesco Marino is from the School of Rural Medicine at Charles Sturt University. He is the Associate Editor of the Journal of Thermal Biology
"In this report, the WHO and WMO warn that climate change is exposing billions of workers worldwide to dangerous levels of heat. With 2024 the hottest year on record, rising global temperatures are driving more heat-related illness, lost productivity, and worsening poverty.
The health risks include dehydration, kidney disease, heat exhaustion, and heat stroke, with a serious drop in productivity relative to the temperature.
There are potential solutions, but this would require serious cooperation from many agencies. Some of the key measures include shaded rest areas, scheduled cooling and hydration breaks, protective clothing innovations, and real-time heat monitoring systems. Improved ventilation and airflow can be provided with minimal changes to structure and the addition of high speed fans. Adjustments to shift times and exposure time over days and worker education seem obvious, cost-effective strategies.
In my view, there are at least 5 practical solutions to protect workers from extreme heat:
1. Cooling and hydration breaks
- Scheduled rest in shaded or cooled areas
- Easy access to safe drinking water throughout shifts, but education about the dangers of overdrinking is also essential.
2. Smarter work scheduling
- Shift work to cooler times of day
- Rotate tasks to reduce prolonged exposure to direct sun and heat
3. Protective clothing and equipment
- Lightweight, breathable, reflective fabrics
- Personal cooling gear (e.g. cooling vests, neck wraps) for high-risk jobs
4. Engineering and environmental design
- Improve workplace ventilation and shading
- Use reflective roofing and cooler building materials to lower radiant heat
5. Training and real-time monitoring
- Educate workers and supervisors to recognise early signs of heat illness
- Deploy heat index alerts and wearable sensors to track body strain in real time"
Dr Liz Hanna is Honorary Associate Professor within the Institute for Climate, Energy & Disaster Solutions, Fenner School for Environment and Society at The Australian National University (ANU)
The WMO / WHO report is a welcome addition to global efforts to protect working populations from growing health risks for workers in hot settings.
With global warming intensifying heat, needless deaths will be inevitable unless ALL countries adopt the recommendations promptly.
Two key features are missing from the recommendations, and both relate to the differences in how individuals respond to heat exposure, and how it impacts them physiologically.
Heat tolerance varies both between individuals and within an individual according to their level of heat-fitness on the day. This means workers must have the right to withhold their labour when they are feeling ill-effects from the heat. Not all workers currently have that life-preserving right.
Secondly, my research with Australian heat-exposed workers revealed significant over-estimation in their own heat tolerance. This reinforces my earlier recommendation and suggests a need for health education /health promotion.
Such education programs ought include 5 key pillars:
- Knowing the general health risks of heat exposure
- Knowing personal risks of heat exposure
- Recognizing early symptoms
- Knowing how to reduce and manage the symptoms
- Recognizing when symptoms are severe, and need urgent medical intervention
Dr Arnagretta Hunter is a physician and cardiologist and is the Human Futures Fellow at ANU.
"Heat is a natural phenomena that has a real impact on the health and wellbeing of people and places particularly in a hot continent like Australia. Heat impacts all of us from early childhood to old age, with no part of life immune from the health impacts of extreme temperatures.
As the global temperatures rise and extreme weather events rise in frequency, intensity and severity, it is of key importance for our communities to appreciate and discuss the health impacts of high temperatures and what we can do to reduce this."
Adjunct Professor Dino Pisaniello is from the School of Public Health at the University of Adelaide and Chair of the College of Fellows of the Australian Institute of Health and Safety
"This document is one of several recent international reports that provide an overview and guidance on occupational heat-health in the context of climate change. It has detailed information on the causes and prevention of a range of health-related outcomes, including mental health. From the point of overall risk to workers, however, it doesn’t capture the important dimension of safety which is often the focus for work health and safety regulators.
Research from a range of Australian universities has shed light on how heat stress can interact with physical hazards to increase the likelihood of traumatic injury and death. Examples are heat stress-induced loss of concentration, grip strength and behaviour change leading to falls from ladders, accidents with power tools, increased chemical exposure and so on. There should be an equal focus on safety to provide a balanced scorecard and a more holistic approach to prevention efforts in a warming climate."
