The WHO warns that the health of two out of three workers is at risk.

BarcelonaFor employees, it increases the risk of heat exhaustion and injuries, and, in the long term, neurological and cardiovascular diseases. For companies, it means more lost work hours, higher costs due to having to hire staff to cover overtime or sick leave, and even facing legal sanctions. The World Health Organization (WHO) and the World Meteorological Organization (WMO) estimate in a report published this Friday that two out of three workers worldwide are exposed to risks associated with extreme heat, and that this poses "new and growing challenges" in the workplace that must be urgently addressed.

The analysis highlights that the unchecked rise in temperatures due to the climate crisis puts the health of approximately 2.4 billion people at risk each year. In fact, there are an estimated 22.85 million workplace injuries, nearly 19,000 deaths, and some 26 million cases of chronic kidney disease, as well as lower productivity, both physical and mental.

In fact, for every degree above 20°C recorded in a territory, employees' work performance drops by between 2 and 3%. This means that on a day when temperatures exceed 30°C, workers could lose between 20% and 30% of their usual performance if protective measures are not in place. If this heat continues for a week, productivity would fall to half or even a third of its usual level.

The authors of the study assure that the document published this Friday is the "first major update" on the impact of heat on the workplace since 1969 and justify their preparation given the "seriousness" of the situation in recent years. Those responsible for the publication emphasize that working in an environment with high temperatures "not only causes discomfort, but is dangerous and even fatal."

"[We are facing] a global societal challenge, one that is no longer limited to countries near the equator, as the recent heatwave in Europe demonstrates," said WMO Assistant Secretary-General Ko Barrett, who warned: "Protecting workers from extreme heat is not just a health imperative, but a necessity."

The document notes that rising temperatures are already affecting manual workers in outdoor sectors such as agriculture, construction, and fishing, and states that extreme heat is a "silent killer." Health risks include heatstroke, dehydration, kidney dysfunction, and neurological disorders. The authors pay particular attention to migrant workers, who they say tend to have less experience and less perceived health risks at work, while also holding more manual jobs that require working outdoors, thus exposing them to "heat stress."

In this regard, they recommend special monitoring systems and extra protection for these groups, and remind us that protecting workers from heat should be a global standard, not a voluntary option.

Increasingly frequent episodes

Both United Nations (UN) agencies call for sector- and region-specific measures developed jointly by employers, workers, unions, and public health experts, taking into account that the frequency and intensity of extreme heat events have increased "considerably" in recent years. They also emphasize that daytime temperatures exceeding 40°C are increasingly common.

To "reshape" the world of work, the authors recommend that governments create adaptive and flexible laws that take into account local realities and that they study the feasibility of setting maximum legal working temperatures, as some Gulf and Latin American countries already do. However, they emphasize that working in a wheat field at 34°C with high humidity is not the same as working in a ventilated office at 28°C, and that thresholds must be adjusted according to context.

The report also warns that many cases of heat exhaustion and heat stress are misdiagnosed as mild dehydration or exhaustion, making it necessary to train healthcare professionals and those responsible for occupational safety so they know how to identify real symptoms and respond quickly. This includes clear protocols indicating, among other things, when to transfer the affected person to a hospital, when to stop a task, and how to administer first aid.

"We can't just say it's 35°C," says Rüdiger Krech, director of the WHO's Health Promotion department. "We need every facility, every community, and every hospital to think about concrete measures to adapt to the heat," he concludes.