How to prevent a hellish summer from destroying health and the economy

In a country of 1,4 billion people - where at least half the workforce works outdoors and only 10 percent have air conditioning at home - the heat is not just an inconvenience. It poses a threat to the economy, livelihoods and health.

"Heat waves are becoming more frequent in India, spreading to new geographical areas and occurring earlier than expected," said Purnamita Dasgupta, a professor of environmental economics at the University of Delhi. During these waves, temperatures can exceed 50 degrees.

As temperatures rise, productivity declines. In 2023 alone, India lost 182 billion potential working hours due to extreme heat, according to the medical journal The Lancet. By 2030, the country could lose the equivalent of 34 million full-time jobs.

Agriculture and construction will be hardest hit, but the risks are not limited to outdoor work. Poorly ventilated homes in densely populated areas trap heat, making it difficult to recover from high daytime temperatures.

Authorities are starting to react. Some local governments are introducing regulations requiring employers to provide shade, breaks and water. Some employers are taking measures on their own to regain lost productivity.

“But the reality is that in most cases productivity still drops,” says Dasgupta. At 35 degrees, a worker doing a medium-intensity job loses about 50 percent of their work capacity.

When such a decline spreads across the entire economy, it becomes a huge burden on the economy.

The global impact of heat on economic growth

According to Climate Transparency, in 2021, heat caused losses of about $159 billion in sectors such as manufacturing, agriculture, services and construction - accounting for 5,4 percent of India's GDP. Similar losses are projected for countries such as Thailand, Cambodia and Pakistan by 2030.

These losses are particularly threatening to developing countries with ambitious growth goals, such as India's plan to become a fully developed country by 2047.

And the problem is global. Heat-related economic losses in the United States already cost about $100 billion a year. The Atlantic Council, a US think tank, estimates that this could reach $500 billion a year over the next 25 years. In Europe, heat waves have already reduced GDP by 0,3 to 0,5 percent. That may not seem like much, but if adaptation to the heat is not accelerated, these losses could quadruple by 2060.

Heat and health: a quiet emergency

Heat doesn't just hurt economies—it also threatens lives. Researchers at the University of California, Berkeley estimate that just one day of extreme heat in India leads to 3.400 more deaths than average, and a five-day heat wave raises that number to about 30.000.

Europe, the fastest-warming continent in the world, is already feeling the deadly effects. In the summer of 2022 alone, high temperatures led to 61.000 excess deaths, mostly among the elderly.

"We all think of heatstroke or exhaustion - think of someone collapsing at the end of a run on a hot day - and those are the obvious cases," says Dr Sandy Robertson, an emergency physician in the UK. "But actually, the worst part of the illness comes a day or two later."

In India, Dasgupta says that the poor workers she interviewed often don’t even seek medical attention for heat-related illnesses because they don’t realize they need help. During heatwaves in the UK, Robertson sees an increase in strokes, respiratory problems, heart attacks – and even violent injuries, as aggression increases as temperatures rise. Prolonged exposure to heat has also been linked to kidney disease, poor mental health and reduced cognitive function.

Healthcare workers are not immune to the heat either. Many British hospitals do not have air conditioning. When temperatures in hospital wards exceed 26°C, overheating occurs, endangering patient safety, straining staff and causing equipment failure, including refrigerators that store life-saving medicines.

"We've had cases where hospital IT systems have completely failed because they've overheated," says Robertson. "If you add to that a crowded ward and extreme heat, it makes the day even more stressful, and a system failure makes it even more difficult to work."

Robertson recommends simple steps to protect yourself during hot weather, such as checking to see if any medications are affecting your body's tolerance to heat, checking in with elderly neighbors, and cooling your home by ventilating at night and closing blinds during the day.

Designing cities to mitigate heat

Dangerous temperatures that fill emergency rooms are more common in cities. Asphalt, concrete, and other urban infrastructure absorb and release heat much more than natural habitats, such as forests. In particularly dense cities with little green space, this urban heat island effect increases daytime temperatures by up to 7 °F (3,9 °C) compared to surrounding areas.

One way to mitigate the impact of heat is air conditioning, which can be crucial for vulnerable groups, such as the elderly. But if air conditioners run on electricity from fossil fuels, they contribute to greenhouse gas emissions that exacerbate climate change and heat waves themselves. Air conditioning also exacerbates the heat island effect, raising nighttime outdoor temperatures by about 1 °C.

Instead, smart urban planning that includes lots of green space and other simple tricks is key, says Nik Rajkovic, an architect and professor at the University at Buffalo.

In Seville, Spain, narrow streets create shade and lower temperatures. Los Angeles painted its streets white to reflect heat. In the Chinese city of Xiamen, green roofs lowered the city's temperature by almost 1 °C.

"We used to plant trees along the streets because they cooled the horses while they pulled carts," Rajković notes.

Another useful approach is to think about the design of buildings. As with cities - it is worth looking back.

"Before air conditioning was invented, we relied much more on natural ventilation in buildings," says Rajković.

In the arid southwestern United States, Pueblo Indians developed a building style with thick walls made of a mixture of earth, sand, and straw that absorb heat during the day and release it at night. Flat roofs also collect rainwater. In Burkina Faso, double roofs separated by an air gap allow heat to escape and cool entire buildings.