India lost a whopping 75 billion hours of labour in 2017 due to heatwaves that make outside work extremely difficult for lakhs, says a new research that assesses the vulnerabilities of the nations from rising temperature.

The Indian loss accounts for about 49% of the global labour loss and is equivalent to nearly 39 million people not working at all in 2017, representing 7% of India’s total working population.

Rising temperatures are a risk in occupational health, and as temperatures regularly increase above physiological limits, sustained work becomes more difficult or impossible.

In 2017, 153 billion hours of labour were lost due to heat exposure, an increase of 62 billion hours when compared against the loss encountered in 2000. Most of the losses took place in India, southeast Asia, sub-Saharan Africa and South America that are already vulnerable.

Around 80% of these losses were in the agricultural sector (122 billion hours lost), 17.5% were in the industry sector (27 billion), and 2.5% were in the service sector (4 billion), says the study published in the November 28 issue of the journal Lancet.

The findings are released days before the start of the UN Climate Summit in Poland where the world is to finalise the rule book for the implementation of the emission reduction targets set in Paris three years ago.

“Vulnerability to extreme heat has steadily increased around the world since 1990, leading to vast losses for national economies and household budgets,” said Joacim Rocklöv, a professor at the Umea University, Sweden and one of the authors of the research paper.

“Those most vulnerable to heat-related risks are the elderly (particularly in urban areas), who have weakened defences against heat as well as manual workers exposed to hot environments like agriculture, construction work and manufacturing,” said Nick Watts, executive director of the Lancet Countdown, a multi-disciplinary research collaboration between academic centres around the world tracking the linkage between climate change and health.

“People with pre-existing medical conditions such as neurological and psychiatric illnesses, heart disease, lung disease, kidney disease and diabetes are vulnerable to heatwaves,” Watts, a fellow at University College London’s Institute for Global Health told DH.

In the past, Indian weather scientists warned about heat waves becoming more intense and frequent in future. In 2015, heatwaves killed nearly more than 2000 people in India.

Worldwide 157 million vulnerable people were exposed to heatwaves globally in 2017 and 153 billion hours of labour were lost due to heat exposure.