I can try to answer this the best I can:
I don't know the total volume of air for the whole city of New York. Lets say it was a sunny summers day and not windy since most smog clouds like those conditions the most. Well, you don't have mountains but you have the whole city of New York and their buildings. The actual physical location would be like 2 to 3 miles away from the city? Can't we have size and speed? I guess I would choose size since we need to blow away all that smog in New York city. I guess the smog is average I suppose. I wouldn't think humidity level would have an impact. Since a high pressure is above new york city the humidity should be around..40%? Not sure how those two variacles interact honestly lol