Cardiac arrests surge as London bakes in record heat

London’s heatwave has triggered a dramatic surge in medical emergencies, with cardiac arrests jumping by more than a third as temperatures soared across the capital.

London Ambulance Service chief executive Jason Killens revealed the service was pushed to its busiest day on record for the most serious emergency calls after temperatures climbed to 35.1C.

The number of 999 calls rocketed by around 50 per cent on Wednesday — rising from an average of about 5,500 to almost 8,000.

Among them were around 650 Category One emergencies, including patients suffering cardiac arrests, breathing failures and other life-threatening conditions.

Mr Killens said: “We took the highest number of calls we categorise as immediately life-threatening in a single day in the history of the ambulance service.”

He warned that the extreme heat was placing particular pressure on commuters, with packed public transport becoming a major problem as temperatures inside trains soared.

“The Tube obviously gets very hot in weather like this,” he said, adding that crews had seen many more people fainting, collapsing and suffering breathing difficulties.

The Standard recorded temperatures of 39.4C on the Central line during the peak of the heatwave, sparking renewed anger over conditions on London’s transport network.

Critics have renewed pressure on Mayor Sir Sadiq Khan over the slow rollout of air-conditioned Underground trains, with no new air-conditioned trains introduced on the Tube for nine years.

The warning comes as London braces for another blast of extreme heat, with temperatures forecast to reach 36C on Friday — potentially making it the capital’s hottest June day on record.

London Ambulance Service has deployed more than 400 additional ambulance crews this week in an effort to cope with the surge in demand.

Officials have urged people to check on elderly relatives, vulnerable neighbours and those with existing health conditions, warning that heat-related heart and respiratory problems can continue even after temperatures begin to fall.

The NHS has warned that the impact of the heatwave could continue to be felt in the days ahead as Britain struggles through one of its most intense spells of summer weather.