New global report calls heat a "public health crisis"
Climate change-driven extreme heat is creating a growing health crisis for workers worldwide, according to a new joint report released this week by the World Health Organization (WHO) and the World Meteorological Organization (WMO).
The guidance warns that both outdoor and indoor workers are increasingly vulnerable to heat-related illnesses as global temperatures continue to rise. The report, Climate change and workplace heat stress, draws on five decades of research and highlights the urgent need for governments, employers, and health authorities to act.
“Heat stress is already harming the health and livelihoods of billions of workers, especially in the most vulnerable communities,” said Dr. Jeremy Farrar, WHO’s 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.”
Health impacts of rising heat
The WMO noted that 2024 was the hottest year ever recorded, with daytime temperatures above 40°C and, in some regions, surpassing 50°C. These conditions have severe consequences for worker health and productivity.
Key findings from the report show:
- Worker productivity drops 2% to 3% for every degree above 20°C.
- Health risks include heatstroke, dehydration, kidney dysfunction, and neurological disorders.
- Approximately half of the global population suffers adverse impacts of high heat.
“Occupational heat stress has become a global societal challenge, which is no longer confined to countries located close to the equator – as highlighted by the recent heatwave in Europe,” said Ko Barrett, WMO deputy secretary-general. “Protection of workers from extreme heat is not just a health imperative but an economic necessity.”
Canadian workers not immune
Although Canada is generally considered a cooler climate, experts warn that Canadian workers face significant risks.
“In Canada, unfortunately we have these weather extremes. We go from cold to hot. And so our bodies essentially lose that (heat) adaptation during the winter period,” said Glen Kenny, University of Ottawa research chair in environmental physiology, who contributed to the international report.
Kenny added that the cumulative effects of working in the heat day after day can compromise a worker’s health. “If I take a worker on a Monday and look at their body’s capacity to lose heat, they are not the same person by day five,” he said.
Dr. Melissa Lem, president of the Canadian Association of Physicians for the Environment, echoed those concerns.
“Workers’ cognitive functions can be impaired so they can have more trouble concentrating, their performance suffers, they have higher rates of injury,” she said.
Call for urgent action
The WHO/WMO guidance recommends occupational heat action plans, including flexible work hours, regular breaks, access to shade or cooling, and clothing that balances safety with ventilation The Canadian Press reported. It also urges the adoption of “buddy systems” so workers can monitor one another for symptoms of heat stress.
“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 International Labour Organization. He noted that more than 2.4 billion workers globally are exposed to excessive heat, resulting in over 22 million workplace injuries annually.
The report underscores the need not only for adaptation but also long-term solutions. As Lem emphasized, “One of the best ways to keep them safe is capping greenhouse gas emissions and reducing our use and extraction of fossil fuels.”
