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Hundreds of migrant construction workers are likely to have died of heat stress while building soccer stadiums in the Qatari desert for the recent Fifa World Cup.

But people’s exposure to extreme heat – temperatures of 38°C and higher – is becoming widespread as climate-related temperatures soar.

“Billions of people are already exposed to dangerous heat at work, elevating their risk of heat stroke, dehydration, kidney disease and other serious illnesses,” Dr Rüdiger Krech, World Health Organization (WHO) director of Environment, Climate Change and Health, told a media briefing on Thursday.

“In agriculture, construction and other physically demanding sectors, we’re seeing a clear rise in heat stroke, dehydration and long-term kidney and cardiovascular damage due to dangerous working conditions,” added Krech during the launch of a new report on heat stress, published by the WHO and the World Meteorological Organization (WMO).

“The workers keeping our societies running are paying the highest price. These impacts are especially severe in vulnerable communities with limited access to cooling health care and protective labour policies.”

WMO director Johan Stander told the media briefing that the past 10 years are the hottest on record and 2024 was the hottest year ever.

Extreme heat has “accelerated” in Europe, Africa, North America and Asia, where new record temperatures were recorded, he added.

“In the Middle East, we’ve seen temperatures in the region of 50°C, and areas in Europe have topped around 40°C.”

The report defines workplace heat stress as “increased heat storage in the body of a worker as a result of excessive heat exposure in the workplace”. This can be due to hot environmental conditions, increased metabolic heat from performing physically demanding tasks; and/ or the requirement to wear heavy protective clothing, which limits the body’s ability to dissipate heat (for example, health workers wearing PPE in hot climates during disease outbreaks).

It describes heat stroke as “a life-threatening condition defined by profound central nervous system dysfunction”, including severe disorientation, seizures, coma.

Outdoor construction and agricultural work during the hot season are considered the highest-risk occupations for experiencing morbidity and mortality associated with workplace heat stress.

Safe working environments

The International Labour Organization (ILO)’s Joaquim Pintado Nunes told the briefing that it is mandatory for the 187 countries that are ILO members “to promote safe and healthy working environments”.

“More than 2.4 billion workers are exposed to excessive heat, and this represents 71% of the world’s total working population,” said Nunes, the ILO’s head of Occupational Safety and Health and the Working Environment.

Heat exposure causes more than 22 million occupational injuries and almost 19,000 deaths each year, according to an ILO report published last year. In 2020, there were an estimated 26.2 million persons living with chronic kidney disease attributable to workplace heat stress.

The ILO report found that workers in Africa (92.9%) and the Arab states (83.6%) had the worst heat exposure, but the fastest changing working conditions are in Europe and Central Asia, with the proportion of workers affected rising by 17.3%, almost double the global average increase.

“Heat exhaustion and sometimes fatal heatstroke have been repeatedly reported among coal miners, surface miner workers and gold miners, as well as workers in agriculture and construction workers in the United States of America,” according to the WHO-WMO report.

“Climate change is reshaping the world of work,” said Nunes. “Without bold, coordinated action, heat stress will become one of the most devastating occupational hazards of our time, leading to a significant loss of life, significant loss of productivity and with catastrophic effects in the future of work.”

Data about workers’ conditions is often hard to come by. To establish the cause of death of the migrant workers in Qatar, researchers triangulated the mortality data of Nepalese migrants in Qatar, interviews with returning migrants about their working conditions, and temperatures.

Most of the migrant workers were young men aged 25 to 35. Globally, this group usually only records a 15% death rate from cardiovascular disease (CVD). But 22% of the Nepalese migrants who died while working in Qatar died of CVD in the cool season and 58% died in the hot season – which the researchers concluded to be likely due to “extreme heat stress”.

Clear recommendations

The report, the first on the subject since 1969, offers guidance to governments, workers, employers, local authorities and health experts to mitigate heat stress.

Recommendations include occupational heat-health policies with “tailored plans and advisories that consider local weather patterns, specific jobs, and worker vulnerabilities”.

Those most vulnerable to heat include middle-aged and older workers, people with chronic health conditions and lower physical fitness.

The report also recommends educating all stakeholders on how to recognise and treat the symptoms of heat stress – particularly essential for subsistence farmers, who are not part of organised workplaces and may not understand what is happening to them.

Krech told reporters that the threshold for the human body is 38°C, over which it is dangerous to work.

Professor Andreas Flouris from the University of Thessaly in Greece said that there is “ongoing discussion” in Europe on “moving towards thresholds of environmental limits where workers can safely work”.

Cyprus, Spain, Belgium already have such thresholds defined in legislation, added Flouris, who was the report’s editor.

“The report provides the evidence that policy makers can use to convince both the employers and the workers that it’s in their best interest for both in terms of health but also productivity, to move to such solutions,” said Flouris.

Image Credits: Shraga Kopstein/ Unsplash, WHO-WMO.