As the country become more developed the pressure to clean up the air will increase. You gave the example of England... Beijing and other emerging cities have same issue.

Last Sunday I transited DEL and could see squat out the window. How the pilot managed to park the A380 I was on safely I don't know. The tail and Fwd cameras just showed smog and faint lights. I continued on a AI 788, and couldn't see the wingtip from my window, which indicates a visibilibility of maybe a 100ft? CatIIIb says all you need is 200ft. The 788 and other A32S of all airlines ahead of us managed nicely, albeit with very very slow taxi and lots of spacing. The fog is also very low, 2 seconds post take off we were out of it and I could see the DEL tower sticking out of it, so it must have been <50-60m tops.