​​Sadiq Khan reveals a health scare and talks about his quest for cleaner air

But another health scare followed, namely a suspected minor heart attack in November 2021 which threatened his key appearance at the Cop26 summit, a story he recounts in his new book, Breathe: Tackling The Climate Emergency.

At a clean energy event in Glasgow the day before he was to take to the Cop26 plenary stage, he walked on to the podium but felt his chest tighten and was unable to speak. He was carried off drenched in sweat, barely conscious, he recalls in the book.

Placed near a window for some fresh air, and given some chocolate canapés from the organisers, he started to feel a bit better and initially declined a trip to hospital, as he didn’t want to make a fuss and felt able to walk.

Hours later, on the insistence of his wife – who was not at the event but saw a tweet from a local government journalist which incorrectly said an ambulance had been called – he was taken to A&E where, after a number of tests, he was told there was a possibility that earlier that evening he’d had a minor heart attack.

Khan, 52, plays down the incident today, saying he’s not sure if it was a heart attack, but that there was concern about his symptoms, given his age and profession.

“The reason I went to the hospital was because a medic reminded me of what happened to somebody I hugely admired, John Smith [former Labour leader]. He went to bed feeling a bit poorly and didn’t wake up in the morning.”

“I wasn’t scared,” he continues. “I was annoyed because I’d been prepping my speech for the next day, because it was unnecessary stress about something that shouldn’t be stressful. In hindsight, I realise my wife was scared, my doctor was scared and I felt guilty for making everyone scared.”

While an ECG and chest X-ray came up clear, blood tests showed that the level of troponin, a protein released after unusual heart activity, had doubled.

Further blood tests the next morning gave him the all-clear to leave hospital and he was advised to rest and avoid stress that day, but he ploughed on with his big speech.

Today, he says he’s still not sure if it was a heart attack.

“It depends which expert you speak to. They can’t actually tell you definitively whether it was or it wasn’t. The heart expert I saw said lots of things are explainable but a small percentage aren’t.

“The key thing is to do things to make sure you’re physically fit and mentally fit and to keep an eye on these things. So I’ve got another check-up imminently, in relation to these issues.”

The health scare hasn’t slowed him down, however. He’s running for a historic third term as London Mayor in 2024 and says he loves the campaign trail, meeting people from all walks of life, but won’t be running for party leadership any time soon.

“Keir Starmer’s going to be the next prime minister for the next 20 years. He’ll be busy being the next Prime Minister and I’ll hopefully be busy being the Mayor for the foreseeable future.”

He says his book was inspired by Ella Roberta Adoo-Kissi-Debrah, a nine-year-old girl who died in 2013 following an asthma attack and who became the first person in the UK to have air pollution listed as a cause of death. She lived near the South Circular Road in Lewisham, south-east London.

The book begins with events leading up to him being diagnosed with adult-onset asthma aged 43, after struggling to breathe when running through the polluted air of his local London streets.

Before then, he’d played football on a weekly basis, trained and taken a medical before running the London Marathon in 2014 with then Labour MP and shadow chancellor Ed Balls.

It was only after the marathon, when he was jogging regularly near his home in Tooting – an area with high levels of air pollution – where he was constituency MP, that he would find himself wheezing after a long run. That wheeze turned into a cough, which proved a problem in the run-up to the 2015 general election, undermining his performance during live radio interviews.

“I was knocked for six,” he says of the diagnosis. “In my school there were two kids with asthma and they didn’t really play sports because of their asthma.”

He now uses an asthma pump twice a day and is also on tablets, but to this day there are times when he struggles to breathe in heavily polluted environments.

The former human rights lawyer still lives in Tooting, where he was born, with his family – wife Saadiya, a lawyer, and two daughters – and he worries about health consequences.

“My mum’s got asthma, she’s 82 (and lives nearby), I’ve got two children, 23 and 21, but I’ve also got nephews and nieces, neighbours and friends. Members of my family could get dementia, heart disease or cancer directly attributable to the poor-quality air. So, of course, there’s a self interest in relation to the impact on me, my family and friends.”

Has he considered moving out of London to a the cleaner countryside?

“That’s one of the reasons I wrote this book. Actually, that sense of complacency, that if you’re outside London the air is clean, that isn’t the case. If you live in a village and you see a car idling outside a church, that’s causing air pollution. And 99% of the world is breathing in toxic air. It’s not simply a city problem.”

The book charts his journey towards a greener city and a greener world, in which he details the challenges he has faced in fighting for cleaner air. Ultra Low Emission Zone (Ulez) expansion, TfL setbacks, cycle lanes, C40 and Cop26 all feature. He sets out seven ways in which environmental action gets blown off course – and how to get it back on track.

Given the training he did before being diagnosed as asthmatic, it’s surprising that he didn’t display symptoms before he ran the marathon.

“The experts say that it’s sustained periods of running on roads. If you think about it logically, the worst air quality is by main roads and most of our commons are near main roads,” he observes.

Ironically, during the first four months of lockdown in 2020 he didn’t use his asthma pump at all – people weren’t driving, there wasn’t the same level of pollution, he points out.

Away from work, he still exercises regularly, running and playing tennis, walks his beloved Labador, Luna, and spends time with family.

How does he maintain a work-life balance?

“If you were to speak to my wife, she would say I don’t,” he says, laughing. “I wasn’t the most popular person in my house two Christmases ago when I took off Christmas Eve to New Year’s Eve to write most of this book.”

When asked what he considers his greatest achievements, he rattles off a train of thoughts: reducing toxic air in the city; planting almost half a million trees; building more homes.

But he doesn’t like the word achievements referred to him.

“When it comes to the A word (achievements) or the L word ( legacy), I think you use those when you come towards the end of your career. I’m still a fraction of the way into my career – so asked me again in 12 years’ time.”

Breathe: Tackling The Climate Emergency by Sadiq Khan is published by Hutchinson Heinemann, priced £16.99.