WHO, WMO warn extreme heat poses growing threat to workers' health

• Worker productivity drops by 2–3% for every degree above 20°C, guidance finds

GENEVA

The World Health Organization (WHO) and the World Meteorological Organization (WMO) have issued a joint report on Friday, warning that extreme heat is placing billions of workers at serious risk, with climate change driving more frequent and intense heatwaves.

"Heat stress is already harming the health and livelihoods of billions of workers, especially in the most vulnerable communities," Dr Jeremy Farrar, WHO assistant director-general for health promotion, disease prevention and care, said. "This new guidance offers practical, evidence-based solutions to protect lives, reduce inequality, and build more resilient workforces in a warming world."

The report, Climate change and workplace heat stress, draws on five decades of evidence and highlights the severe toll rising temperatures take on health and productivity. According to WMO, 2024 was the hottest year on record, with daytime temperatures above 40°C (104 F) and even 50°C becoming increasingly common.

"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 WMO Deputy Secretary-General Ko Barrett. "Protection of workers from extreme heat is not just a health imperative but an economic necessity."

The guidance noted that worker productivity drops by 2–3% for every degree above 20°C. Health risks linked to extreme heat include heatstroke, dehydration, kidney dysfunction and neurological disorders. About half of the world's population is already suffering adverse effects from high temperatures, it stated.

The agencies urged governments and employers to adopt occupational heat action plans, raise awareness of heat stress symptoms, and design affordable, sustainable protections for workers.

"This report represents a critical milestone in our collective response to the growing threat of extreme heat in the world of work," Joaquim Pintado Nunes, International Labour Organization's chief of occupational safety and health, said.