Dr Chris Smith and the Naked Scientist team present the latest science news, analysis and breakthroughs, In this week's episode……four years after they declared COVID 19 a global pandemic, we speak to the World Health Organization to get their recollections and perspectives. A surprising finding about the particles shed from the brake pads on our cars, we look back at the remarkable life of Paul Alexander, the man in the iron lung, who’s died aged 78. And we look at the long term effects of COVID 19. Get the podcast from the BBC Sounds app.