In this episode, Simon and Matt are joined by the Mayor of London, Sadiq Khan.

They discuss his new book, 'Breathe', and his passion and determination to change the air pollution in London - and tackle climate change in the wider world.

Simon gets 'a bit 5 Live' and Matt asks if it's too late! (so, nice and light)

Here comes the science bit:

A seven-step guide to winning support for tough action on climate change - the first book from the Mayor of London, Sadiq Khan.

For many years, Sadiq wasn't fully aware of the dangers posed by air pollution, nor its connection with climate change. Then, at the age of 43, he was unexpectedly diagnosed with adult-onset asthma - brought on by the polluted London air he had been breathing for decades.

Scandalised, Sadiq underwent a political transformation that would see him become one of the most prominent global politicians fighting (and winning) elections on green issues. Since becoming Mayor of London in 2016, he has declared a climate emergency, introduced the world's first Ultra-Low Emission Zone, built hundreds of kilometres of new cycle lanes, led a drive for affordable insulation in council homes, and turned London into the first ever 'National Park City'.

But with every year bringing more wildfires, extreme temperatures and flooding - and with around 4,000 people still dying prematurely from London's polluted air every year, with older, working class and ethnic minority Londoners most affected - there is so much more to do.

Now, Sadiq draws on his experiences to identify the seven ways environmental action gets blown off course. And he reveals how to get it back on track, by:

- Proving to sceptics that the climate crisis is a health crisis too;

- Overcoming voters' cynicism by building coalitions across the political spectrum;

- Shaking hands with everyone from your fiercest opponents to the most steadfast climate activists (even if you're a bit worried they might superglue you).

Breathe is a call to action demonstrating how anyone - whether voter, activist or politician - can win the argument on climate. It will help create a world where we can all breathe again.