I am at practically at a loss for words suffice to say that I am tempted to suggest replacing a coal burner with burning old paper notes would probably do more for air quality.The more we electrify, the cleaner the air will be, resulting in a little less pressure on our beloved NHS due to less respiratory and othet problems.
I work out of Nottingham, and the atmosphere from all the diesels that use the station is nothing short of foul.
Of course had e-voyager gone ahead the problem would have been solved but the electrification brigade insist you must NOT run diesel engines under wires - so you can't have electric trains until every inch is wired from Nottingham to St Pancras.
Seriously the damage done by cars and lorries is many times greater and vastly cheaper to deal with.