PaxBoy
This is hardly new news. The original 2003 recommendation for the Heathrow 3rd runway was made subject to the EU air quality regulation being complied with. The only 'new news' is that compliance is apparently more difficult than was then expected. (I think that the original idea was that a few electrick omnibuses and some restrictions on car access to the central zone would do the trick).
Skipness1Echo
Air quality is not only a matter of NIMBYism. Airport workers have to breathe too (although I'm told not all managers).