*India, particularly New Delhi, because they're really not any better than China. The problem here isn't so much censorship as apathy, both on the part of the public and the politicians.
*Sofia, Bulgaria, where the cause- as it is in India and China- is too many cars on the road. In India and China, the issue is more their sheer volume; in Bulgaria, while that's still true, the crux of the issue is a little different: the cars on the road are ancient and lack decent catalytic converters, or any at all. That, for the non-car people amongst us (myself included), is the device that takes the exhaust a car makes and converts the stuff in the exhaust to something less toxic. When cars in Western Europe become too beat-up, they get sent east, where regulations on cars are more lax, which means Bulgaria gets a lot of cars that are considered no longer good enough for Western European roads. (One of my more recent book purchases, My Mercedes Is
*Actually, you know what, here's a link to the World Health Organization's report on air pollution levels in a variety of world cities, with annual means between 2003 and 2010. What you want is a count of fine particulate matter (smaller than 10 microns) to be smaller than 20 particles per cubic meter; above that, it's a safety concern. The EPA actually prefers the count to be 10 or less, and that's a count you're really only going to find in the North American west. In the data set, Santa Fe, NM; Clearlake, CA; and Whitehorse, YT, Canada lead the pack worldwide, and they sit on 6 particles per cubic meter. Canberra, Australia is the most notable city to come in at 10 per cubic meter; in the United States, think Santa Cruz, CA. A far larger segment of locations comes in when you're looking at the sub-20 set; cities at the 20 level include St. Louis, Helsinki, Milwaukee, Belo Horizonte, and Atlanta. At 25, you're looking at Los Angeles. The worst location in the United States, Bakersfield, CA, sits at 38.
Beijing? 121. Delhi? 198 (New Delhi isn't listed). And that's an average taken from 2003 to 2010. Between this past November and January, New Delhi clocked in at 575... when measuring to a maximum of 2.5 microns. Beijing scored 400.
500 is the equivalent of smoking three-quarters of a cigarette every day.