Bbc Inside Science

This week London's Ultra Low Emission Zone was extended to 18 times its previous size. In an effort to cut levels of various nitrogen oxides and other gases dangerous to humans from urban air, cities encouraging lower emission vehicles is a trend soon stretching across the UK and other European countries. But some are sceptical as to their efficacy. Dr Gary Fuller of Imperial College London is author of The Invisible Killer, and has been studying the air in London and elsewhere since these zones began.As COP26 begins in Glasgow, a wealth of climate science is being published and publicised. Victoria Gill describes a couple of stories this week that point out quite how complex the science is, let alone the diplomacy and economics. Whilst the world's forests taken as a whole undoubtedly still capture more CO2 than they release, research this week shows that ten of Unesco's World Heritage Forests - making up for an area twice the size of Germany - have in the last ten years actually moved from being a carbon sin