Eight out of the top ten areas in England with the highest proportion of singletons are in London.
Scientists say rising summer temperatures will have a greater impact on Londoners' health than residents anywhere else in the country.
Tributes flood in for the 15 year old Hackney girl shot at the weekend.
MP Meg Hillier, the schoolgirl's family said:
"Shereka Marsh was a lovely typical, bubbly outgoing teenager with lots of friends.
"She was not involved in gangs or violence. She did not drink or take drugs. Her mother always knew where she was.
"Shereka was a responsible, hard working young woman with so much to look forward to."
A 15 year old boy accused of shooting dead teenage schoolgirl Shereka Fab-Ann Marsh in London has appeared in court.
Shereka died at a house in Eastway, in Hackney on Saturday afternoon after being shot in the neck.
The boy, who cannot be identified for legal reasons, appeared at Stratford Youth Court charged with murder. He wore a grey fleece and tracksuit bottoms and spoke only to confirm his personal details during the short hearing.
He was remanded in custody to appear at Snaresbrook Crown Court on Wednesday, March 26.
Two 16-year-olds who were also arrested in connection with the shooting have been released without charge, police said.
– Jules Pipe, Mayor of Hackney
The death of a young person is always devastating, and our sympathies are very much with Shereka's friends and family. This incident has sent shockwaves through the community in Hackney and we are working to support pupils and staff at Urswick, where Shereka was a much valued member of the school. This has highlighted once again the danger that firearms pose to society; put simply, guns ruin lives.
Scientists from Imperial College London say that in the most vulnerable districts, in London and the southeast, the odds of dying from heart or lung causes increased by more than 10 per cent for every 1C rise in temperature.
Those most at risk areas include more deprived districts of London such as Hackney and Tower Hamlets, with the odds of dying more than doubling on very hot days.
A Facebook page set up by Shereka's friends - R.I.P Shereka - has over 15,000 likes.
The boy, who cannot be named for legal reasons, is due to appear at Thames Magistrates' Court today.
Shereka Marsh died at a house in Eastway, in Hackney on Saturday after being shot in the neck.
Two 16-years-olds who had been arrested in connection to the shooting have been released without charge, police said.
A 15-year-old boy has been charged with murder following the shooting of teenager Shereka Fab-Ann Marsh in Hackney, east London, on Saturday, Scotland Yard has said.