London's bad enough that you can see and taste the change in air roughly when you reach Hendon on the M1, that it leaves clothes and person dirtier, and general

London's bad enough that you can see and taste the change in air roughly when you reach Hendon on the M1, that it leaves clothes and person dirtier, and generally feels unpleasant like sitting in a room full of smokers. Bad enough to want to avoid it. Which makes reading of cities around the world where it's significantly worse that much gloomier.