More than 500 people are reported to have died in an extreme heatwave in India, where temperatures have hit highs of 118 Fahrenheit in some parts of the country.
According to local media reports, most of the casualties so far have been in the southeastern states of Andhra Pradesh and Telangana.
An official from Andhra Pradesh's Disaster Management Department said 333 people had died since May 18. In Telangana there have been at least 199 deaths, with another 36 reported in the states of Odisha and West Bengal.
The hottest recorded temperature was 118 Fahrenheit in Allahabad in Uttar Pradesh, while in Delhi the mercury hit 111 Fahrenheit.
The homeless are among those most vulnerable to the heat, because they are unable to find shelter. Delhi-based NGO the Centre for Holistic Development said 186 people had died in the capital, 80 percent of them homeless.
"Almost all the victims are old. Inquiries reveal that most of them were working and were exposed to the heat. Dehydration and heat stroke caused the deaths," B.R. Meena, a senior Telangana state official, told the Indian Express newspaper.
"The majority of the victims are people who have been exposed to the sun directly, usually aged 50 and above and from the working classes," P. Tulsi Rani, special commissioner of Andhra Pradesh's disaster management department, told AFP.
In Kolkata, taxi drivers are refusing to work during the hottest part of the day, after a driver reportedly died in his cab.
There were power cuts across the country as India's struggling grid was overloaded with demand. People sought refuge in air-conditioned shopping malls and Delhi's metro.
The number of dead already exceeds the hundreds who died in a heatwave in 2010 when temperatures hit 122 Fahrenheit, in what was the hottest summer since records began. The hottest temperature ever recorded in India was 123 Fahrenheit in the northern town of Alwar in 1956.
Officials have been advising people to drink plenty of fluids, avoid the sun and not go out on an empty stomach. India's National Weather Forecasting Center warned that "heatwave to severe heatwave conditions would prevail" in the coming days, and that residents of areas including Odisha, Jharkhand, and Andhra Pradesh must take action to protect themselves.
Incidences of extreme heat have become more common across the globe in recent years.
A study released last January found that cities across the world were experiencing significantly more heatwaves, which they pointed out may lead to "enhanced heat wave related mortality in urban areas."
Vimal Mishra, an India-based author of the study, told VICE News: "In general heat waves have increased in urban areas around the globe. The current heat waves in India may be associated to large scale climate warming as well as increased urbanization."
Mishra, an assistant professor at the Indian Institute of Technology Gandhinagar, said the current Indian heatwave could continue until thunderstorms arrived or the monsoon began. "In case of a delayed monsoon, the condition may worsen. Short term precautionary measures should be taken to avoid adverse impact of heat waves and high temperature."
However, in the longer term, Mishra said, "We need to smartly plan our urban areas that are more sustainable and have more forest cover and water bodies."
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