Well, 10km^2 is pretty tiny in a country the size of China, and I'm not sure how high up the pollution goes (higher than buildings but lower than planes). So i

Well, 10km^2 is pretty tiny in a country the size of China, and I'm not sure how high up the pollution goes (higher than buildings but lower than planes). So it's still a lot of pollution, just much less actual mass than I would have guessed.