While I was in London a few days ago, I saw this sign–often. A bit of background: there’s tons of discussion here around expanding airports, building a new one, or some mix. LGW has these adds running.
The part I don’t get is the environmental angle. Assuming that the elevation, temperature, and other variables are apx the same, wouldn’t a given airplane pollute the same regardless of what airport it took off from? It doesn’t make much sense to me…