POLLUTION By Isobel Holbourn Isobel watches the weather forecast on TV and is appalled at the poor air quality over parts of England. Above the M4 there's a blanket of filth. She finds it incredible, coming from somewhere like Shetland, to see six lanes of traffic, with one person in each car. It's madness. The air in Foula is excellent, and it could be the same in London or Birmingham.