The Wikipedia article claims air pollution from living in New York or Boston is 30 times worse than the risk from living with a smoker, though that was in 1979. Presumably air pollution has become much less severe since then. Does anyone know the figure today?
These days people vastly overestimate the risk of second-hand smoke. Based on the numbers in this article living with a smoker is equivalent to smoking a pack of cigarettes every two years. i.e. not much.
Second-hand smoke does have some health consequences -- for instance poor air quality is strongly linked to childhood asthma. It's also certainly considered a nuisance by most people.
Anyway, I'm not surprised at all that living in a polluted city would expose you to far more danger than a smoker at home. 30x sounds fairly reasonable.
Indeed, the EPA has steadily increased the stringency of particulate matter (PM) standards over the years (these have an impact on car/engine design and fuel (sulphur and nitrogen content)); you can find more information here:
