WHO and WMO Warn of Rising Worker Health Risks as Extreme Heat Intensifies

The World Health Organization (WHO) and the World Meteorological Organization (WMO) have released a new joint report and technical guidance highlighting the escalating health and economic risks posed by extreme heat on workers worldwide. The report, entitled Climate Change and Workplace Heat Stress, draws on five decades of scientific research, underscoring how climate change is reshaping working environments and placing billions of workers at risk.

Heat Stress: A Growing Global Challenge

The findings are stark: the frequency and intensity of extreme heat events have risen sharply, with daytime temperatures above 40°C and even 50°C becoming more common across many regions. The year 2024 was the hottest on record, according to WMO, signaling a worrying trend that endangers both lives and livelihoods.

Health risks associated with heat stress include:

• Heatstroke and dehydration

• Kidney dysfunction linked to chronic exposure to high temperatures

• Neurological disorders impairing worker safety and performance

• Long-term productivity loss affecting household incomes and economic stability

In fact, the report reveals that worker productivity declines by 2–3% for every degree Celsius above 20°C. This has enormous implications for industries heavily reliant on manual labor, such as agriculture, construction, fisheries, and manufacturing, where workers face prolonged exposure to dangerous heat.

Billions Already Affected

WHO estimates that half of the global population is already suffering from the adverse impacts of high temperatures. Vulnerable groups—such as children, older adults, low-income populations, and those with pre-existing health conditions—are disproportionately affected.

“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 offers practical, evidence-based solutions to protect lives, reduce inequality, and build more resilient workforces in a warming world.”

An Economic and Social Imperative

The WMO stressed that the crisis is not only a health emergency but also an economic necessity. “Occupational heat stress has become a global societal challenge, which is no longer confined to countries close to the equator – as highlighted by the recent heatwave in Europe,” said Ko Barrett, WMO Deputy Secretary-General.

Productivity losses, rising medical costs, and increased absenteeism are all undermining economic growth. Without urgent measures, experts warn that climate-driven heat stress could roll back progress in poverty reduction, public health, and decent work.

Recommended Actions for Governments and Employers

The guidance sets out a clear roadmap for addressing workplace heat stress, urging governments, employers, trade unions, and health authorities to act decisively. Key recommendations include:

• Develop occupational heat-health policies tailored to local weather patterns and job risks.

• Protect vulnerable groups such as older workers, those with chronic conditions, and individuals with lower physical fitness.

• Raise awareness among employers, health professionals, and first responders to properly identify and treat heat-related conditions, which are often misdiagnosed.

• Engage all stakeholders—from workers and unions to local authorities and experts—in the co-creation of locally relevant heat-health strategies.

• Adopt practical, affordable, and environmentally sustainable solutions to ensure scalability.

• Promote innovation, such as wearable technologies, cooling systems, and workplace design that minimizes exposure.

• Support research and evaluation to improve the effectiveness of occupational health interventions.

Complementing ILO’s Global Findings

The WHO–WMO report builds on the International Labour Organization’s (ILO) earlier findings, which reveal that over 2.4 billion workers worldwide are exposed to excessive heat. This exposure contributes to more than 22.85 million occupational injuries every year, a figure that is expected to rise with accelerating climate change.

“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, Chief of Occupational Safety and Health at the ILO. “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.”

A Call for Urgent Action

The report underscores the urgency of integrating occupational heat action plans into broader climate adaptation and public health policies. It stresses that protecting workers from extreme heat is not only vital to achieving the United Nations Sustainable Development Goals (SDGs) but also essential to reducing inequality and safeguarding economic growth.

Immediate steps are needed to prevent the worst outcomes of climate change. Without intervention, billions of workers may face declining health, shortened life expectancy, and reduced income opportunities.

As Dr. Farrar concluded, the message is clear: “Protecting workers from heat stress is a matter of dignity, equality, and survival. Inaction is no longer an option.”