sorry don't agree. It may not be the cleanest air, and i am sure there is data out there about car, bus emissions, but chimneys, you would be hard pressed to find a home, business with a chimney, or one that is working.
You can't use the old fossil fuels anymore, as far as i know. This isn't Victorian fog encrusted London. The people can whiff a bit i grant you.
And as you are a resident of Brighton, Brightonian? there must be a similar problem going on the amount of people that live and visit, and your buses don't look that much better than the ones we have here.