Hot working conditions greatly increase serious illness and decrease productivity

One in three individuals working in hot conditions experience hyperthermia or more serious symptoms of heat illness, such as acute kidney injury, nausea or fainting, a new study published in the Lancet Planetary Health has revealed.

Firefighters were one of the at-risk groups which the study looked at

Researchers have analysed data from more than 447 million workers from over 40 different occupations across the globe and found that individuals working under heat stress had an average body temperature of 37.6°C, much higher than the 36.9°C for those working in normal conditions.

The at-risk group was four times more likely to experience heat strain, a condition with important effects for the body’s physiological function that includes symptoms such as elevated hyperthermia, dehydration, kidney injury, nausea, fainting, and muscle cramps.

The team, which included Loughborough University Professor of Environmental Physiology and Ergonomics George Havenith, looked at data from 111 studies from 30 countries and published their findings in the journal, The Lancet, Planetary Health.

Some of the professions which the scientists included were:

  • Industrial workers
  • Miners
  • Firefighters
  • Agricultural workers
  • Steelworkers
  • Fruit and crop pickers
  • Kitchen staff
  • Bakers

The study, Workers’ health and productivity under occupational heat strain: a systematic review and meta-analysis, also showed that hot conditions affected productivity.

“The impacts of occupational heat strain are not limited to health. They also include productivity,” said Dr Andreas Flouris, of the FAME lab in Greece, the lead author in the study.

Of those who worked under heat stress, 30% reported productivity losses.

On average, productivity declined by 2.6% for every degree increase beyond 24°C Wet Bulb Globe Temperature (a type of heat indicator that combines temperature, humidity, wind speed, and radiation).

Prof Havenith, the director of Loughborough’s Environmental Ergonomics Research Centre, said: “Our study demonstrates the important impacts of occupational heat strain on health and productivity and should be recognized globally as a public health problem.

“Together with other organizations, we are working towards implementing actions to mitigate its effects, especially in light of the occurring climate change and the anticipated rise in heat stress.

“Our aim is to establish a global surveillance system that will guide public health policy as well as health and safety planning.”


A steelworker


The pan-European HEAT-SHIELD project is dedicated to addressing the negative impact of increased workplace heat stress on the health and productivity of five strategic European industries: manufacturing, construction, transportation, tourism and agriculture.

The Consortium consists of a group of twelve research institutions, two policy-making organizations, four industrial entities and two civil society organization from across the EU.

The project is funded by the European Commission.

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