The United Nations on Friday called on governments and employers to act urgently to protect workers increasingly exposed to extreme heat.

Rising global temperatures and more frequent, intense heatwaves are already affecting workers’ health worldwide, the U.N. said in a long-overdue update to guidance last issued in 1969.

According to the report, worker productivity drops 2-3% for every degree above 20 degrees Celsius (68 degrees Fahrenheit), with half of the world’s population already feeling the effects of rising temperatures.

The health risks include heatstroke, dehydration, kidney dysfunction and neurological disorders, the World Health Organization and the World Meteorological Organization said.

Manual workers in sectors such as agriculture, construction and fisheries, as well as vulnerable populations like children and older adults in developing countries, are particularly at risk, the agencies added.

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

The agencies called for heat action plans tailored to regions and industries, developed in consultation with workers, employers, unions and public health experts.

Unions in some countries have pushed for maximum legal working temperatures, which the agencies said is one option but would likely vary globally depending on local context.

They also urged better education for health workers and first responders, noting that heat stress is often misdiagnosed.

The International Labour Organization recently found that more than 2.4 billion workers are exposed to excessive heat globally, resulting in more than 22.85 million occupational injuries each year.

"No one should have to risk kidney failure or collapse just to earn a living,” said Rudiger Krech, WHO director ad interim for environment, climate change and health, at a press conference ahead of the report’s release.