Older people living in the South East of England are especially vulnerable to dying in heatwaves, new research has revealed.
The area, which has the highest concentration of better-off households, could be at a greatest risk of more summer deaths due to climate change.
The study found that in deprived districts of London, such as Tower Hamlets, the risk of dying more than doubles on very hot days.
Districts in the far North were much more resilient, seeing no increase in deaths at equivalent temperatures.
The research looked at temperature records and mortality figures from 2001 to 2010 and showed the odds of dying from cardiovascular or respiratory causes increased by more than 10 per cent for every 1C rise in temperature.
Majid Ezzati, from Imperial College London, said: “We might expect people in areas that tend to be warmer would be more resilient because they adapt by installing air conditioning for example.
“These results show that this isn’t the case in England and Wales.”
He added that more densely packed housing, which could retain more heat, and worse access to community healthcare could be factors.
The study also said having less contact with friends, family and neighbours could be another explanation.
Research published last year found that people living in London experienced the highest rate of loneliness across the country, while people in the North West and East Midlands were less likely to feel isolated.
The study, published in the journal Nature Climate Change, looked at mortality due to warmer summer temperatures in England and Wales.
It found that when temperatures rose to just 2C warmer than average, it could cause another 1,550 extra deaths.
Of those who succumbed to the hotter weather just over half would be people over 85, with 62 per cent women.
The extra deaths would be spread unevenly, with 95 of the 376 total districts accounting for half of all deaths.
The effects were similar in urban and rural districts, but the most vulnerable included deprived areas in London, such as Hackney and Tower Hamlets, with the odds of dying more than doubling on very hot days.
Researchers said the trend could not be explained by the general warmer weather in the south.
They also ruled out a higher life expectancy, meaning a higher population of older people, because the same results were found even when the scientists considered deaths in specific age groups.
Philip Staddon, who researches climate change and health at the University of Exeter, said: “The more resilient areas are in the poorer North and West, whereas the affluent South East seems least resilient.”
In Britain, cold temperatures are responsible for about 40,000 extra deaths, compared with 2,000 each summer – meaning that a warmer climate could have some health benefits.
However, recent research, led by Dr Staddon, suggested that while there is still a peak in deaths during winter due to seasonal illnesses such as flu, better housing and healthcare meant we are far less vulnerable to the cold.
Professor Ezzati said: “Many things can be done at the local level to reduce the impact of warm spells, like alerting the public and planning for emergency services.”