The numerical values of pollution does not say how much it influences the normal traveller in activities when he/she visits such cities. Is it a minor inconvenience or are you literally choking? How about walking or sleeping during night? Is the effect tolerable for a short time, does it get worse or are you adjusting to it?
How do you prepare if you want to visit such cities? Do you buy face masks and do they work? Do you visit such cities even if you have already a respiratory problem?