UN Warns Excessive Heat Is Harming Worker Health, Productivity

August 25, 2025

As global temperatures continue to rise, the risks to workers’ productivity and health also are worsening, a United Nations study released Friday found.

For every degree above 20C (68F), worker productivity drops between 2% and 3%, according to analysis from the World Health Organization and the World Meteorological Organization. More than a third of people who frequently work in hot temperatures experience physiological heat strain, which is associated with conditions including impaired kidney function, dehydration and neurological dysfunction.

Around the world, more than 2.4 billion workers are exposed to workplace heat stress, according to the International Labor Organization. Those especially at risk are workers in agriculture, construction, and other physically demanding sectors, the report says.

“Extreme heat is a public health crisis. It’s already harming the health and livelihoods of billions of workers across the globe,” Rüdiger Krech, WHO’s director of environment, climate change and health, told reporters on Thursday. “No one should have to risk kidney failure or collapse just to earn their living.”

Lesser-developed populations are particularly at risk, Krech said, pointing to “vulnerable communities with limited access to cooling, healthcare and protective labor policies.”

The warning strikes a particular chord in tropical climates. Singapore’s first prime minister, the late Lee Kuan Yew, famously quipped that air conditioning was the best invention of the 20th century, boosting worker productivity and helping the city-state catapult to its developed-nation status.

Some data suggest that kidney problems are common among 15% of people who work under heat stress for six or more hours every day, for five days a week, over at least two months. In 2020, there were about 26.2 million individuals living with chronic kidney disease attributable to workplace heat stress, according to the report.

The study is the first major update, with “comprehensive evidence,” on the effects of climate change on workers since 1969, Krech said. About 30% of those who work under workplace heat stress conditions reported that they were also less productive.