Khan doesn’t answer directly, but his response suggests he knows it is in need of urgent resuscitation. Anyone doubting this decision should take a long walk along the north and south circular and reason with the families living there why they don't deserve cleaner air.

Now for the good news, naturally provided in the form of stats – 36,000 affordable houses a year built under him as opposed to 25,000 under Johnson; more council houses completed than at any time since the 70s; a proposed rent freeze in London. The Breathe London Network, managed by Imperial College London and funded by the Mayor and Bloomberg Philanthropies and the boroughs, is an important part of Sadiq’s work to raise awareness of air pollution, making it easier for all Londoners to access reliable, localised, real-time air quality data. Dr Gary Fuller, Senior Lecturer from the School of Public Health at Imperial College London, said: "The new Breathe London network of sensors ​ across the city's boroughs will help communities to understand the invisible air pollution that surrounds them. Expanding these world leading standards to the whole city will mean that millions more people will be able to breathe cleaner air and live healthier lives. In today’s episode of Ways to Change the World, Sadiq talks to Krishnan about his new book, ‘Breathe’, in which explores why tackling the climate emergency has become his defining policy, as the mayor of London.It tackles his commitment to “effective climate action” and presents obstacles – fatalism, apathy, cynicism, deprioritisation, hostility, cost and gridlock – and then addresses how to overcome them. He recognises connections between air pollution, global heating, public health and racial inequality.

The proceeds from the book are being donated to the Ella Roberta Foundation, established in memory of Ella Kissi-Debrah, the south London schoolgirl who was the first person in the world to have air pollution listed as a cause of death on her death certificate. That is why we are committed to finding, supporting and sharing creative solutions to tackle this health issue.

Throw into the equation the fact that I’m a parent now - I’ve got my children, I’ve got nephews and nieces, I've got people that I love who live in London and all around the country. Khan’s administration has repeatedly defended the scheme, claiming it is essential to improve river crossings in east London.

Now he portrays himself as an accomplished and pragmatic statesman who has harnessed London’s power to advance the climate agenda. I've been enthused and energised over the last few years because optimism is key and it is a hopeful story. In 2019 alone, 4,000 Londoners died due to toxic air, which disproportionately affects deprived communities, people of colour and people in London’s outer boroughs. As a new feature, successful applicants can choose to receive a lower grant value and up to two free annual bus and tram passes. The point I'm trying to get across is that we can do it, we've shown we can bring about change and there are cities who are doing it around the world right now.

By the way, I’m not comparing what I am going through to some of the stuff people go through – as a lawyer my clients with PTSD were asylum seekers and refugees. Editorial director Rowan Borchers said Breathe would be “both an intriguing inside account of life in City Hall, and a warm and practical guide to green politics”. I think he means he went from driving his Land Rover to running the marathon and caring about the climate.