Breathe less … or ban cars: cities have radically different responses to pollution

When thick smog hits the city, Londoners are advised to avoid exercise, Parisians get free public transport and Beijing limits cars. Which is the best solution?When a thick cloud of air pollution settled in over London last week, experts warned those with health problems to avoid strenuous exercise. The advice to Londoners essentially boiled down to this: breathe less.Meanwhile, as Paris suffered a similar pollution episode – its worst in a decade – officials swung into action, waivi