Heat and work never went well together. And in an overheated world, climate change, with its increasingly frequent heatwaves, is becoming a concrete threat to hundreds of millions of “frontline” workers.

Health at risk, productivity down: how to keep working as before in a warmer world? Can the business model based on high productivity last? Because it makes us work slower and less well, heat costs the world economy more than 2,000 billion dollars (about 1,830 billion euros) every year.

With this documentary which, from Qatar to France via the United States, India, Italy or Nicaragua, sheds light on the formidable phenomenon of heat stress by analyzing the health, economic and environmental issues, Mikaël Lefrançois and Camille Robert have done a remarkable job. They interviewed doctors, architects, economists, heads of NGOs and political leaders whose analyses, coupled with the stories of men and women describing their working conditions unsuited to high temperatures, allow us to better understand the urgency of the situation.

Death, serious kidney disease, fainting, the effects of the climate are terrible for workers who often suffer from hellish speeds and are not protected from scorching temperatures. Main victims: construction workers, in the Gulf countries but also in Europe. In India, the textile workers crammed into gigantic poorly air-conditioned hangars, or the very many seamstresses at home, working in slums where sheet metal and cement trap the heat.

Heart attacks and kidney diseases

Other victims: agricultural workers, like those sugar cane cutters in Central America who work in archaic conditions. The high temperatures associated with intense muscular work and too few breaks cause heart attacks and kidney disease.

Another striking example is that of the UPS delivery drivers in the United States: harassed in real time by managers who track down every minute lost, they have to make between one hundred and thirty and two hundred deliveries a day in an unair-conditioned truck where the temperature can go up to 50 degrees! Accused on numerous occasions by the American labor inspectorate, UPS management claims to care about the health of its employees by equipping the trucks with ventilators and the delivery people with new, more comfortable uniforms. Obviously insufficient measures in a country where, in sixty years, the number of heat waves has tripled.

The situation has become so worrying that Joe Biden and his vice-president, Kamala Harris, have taken up the subject, asking the government agency OSHA to work on regulations intended to prevent heat stress at work.

Judy Chu, Democratic Representative from California, has long fought to bring the climate threat into US labor law. In 2006, a law was enforced in California requiring businesses to take breaks and provide water when the temperature hits 35 degrees. Sufficient ? Heat stress specialist, epidemiologist Tord Kjellström estimates that by the end of the century, at the current rate of warming, “15% of working hours will be lost”.