Extreme heat threatens worker health and productivity, says WHO-WMO report

 As global temperatures continue to rise, companies expanding into new markets will increasingly face decisions about how best to protect workers from the worsening impacts of extreme heat.

In a new report entitled “Climate change and workplace heat stress”, the World Health Organization (WHO) and the World Meteorological Organization (WMO) warn that rising heat is severely impacting worker health and productivity. 

According to the report, more than a third of people who frequently work in hot temperatures experience heat stress, which can lead to or exacerbate a range of conditions, including hyperthermia, syncope, impaired kidney function, dehydration and neurological dysfunction. Additionally, for every degree above 20C (68F) worker productivity drops between 2% and 3%. 

While the report stresses that occupational heat stress is a global problem, it notes that those working in sectors that rely on manual labour – such as construction, agriculture and fishing – are particularly at risk. 

It calls on employers, governments and health service providers to develop heat action programmes to help workers keep cool and stay healthy. “Assessment of workplace heat stress should evaluate a range of job and personal risk factors, while also considering issues related to a worker’s return to work after severe health outcomes associated with heat illness,” the report says.

WMO data shows that over the last decade temperatures have been warmer than ever, with 2024 showing as the hottest year on record. Heatwaves are increasingly common and are expected to become more frequent, especially in areas such as Europe, where temperatures routinely reach 40C (104F), and Africa and the Middle East, which can see temperatures hit as high as 50C (122F). 

Guidance for employers

Along with guidance for governments and health authorities, the report offers several recommendations for actions employers can take to help mitigate the growing risks of extreme heat on their workers. 

These include developing occupational heat-health policies tailored to take into consideration local weather patterns, specific jobs and worker vulnerabilities. Examples include mandating breaks during the hottest parts of the day, allowing workers to remove or adjust their clothing to cool down, installing shade and water stations close to active workers, and planning the most physically intense tasks during cooler parts of the day.

The report also says businesses should give special attention to workers who are more susceptible to the effects of heat stress, such as middle-aged and older workers, those with chronic health conditions and those with lower physical fitness.

While the report’s recommendations are voluntary, many governments have already implemented regulations to address the problem of heat stress in the workplace. Countries including Qatar, the United Arab Emirates and Spain ban outdoor work during the hottest time of day in summer months. And laws in South Africa, Italy and other countries oblige employers to implement measures once the temperature reaches a certain threshold, including reducing the ambient temperature using air conditioning or fans, providing water and shade, shifting timetables and regularly monitoring employee health.

The financial impact of occupational heat stress is significant. The World Economic Forum projects that by 2030 extreme heat will cost companies US$2.4tn in productivity losses annually. Causes of productivity loss can include workers taking unplanned breaks or slowing down to reduce heat stress, as well as sick time taken to deal with the physiological consequences of working in high temperatures.