DriveinSaturday - counter-intuitively, they think you breathe in LESS pollution if you cycle than if you take the bus (lower deck). That's because a) cycles aren't in the main 'stream' of traffic, but out to one side - and can take quiet roads; and b) because a cyclist's 'air intake' (nose) is quite high up, while a car/bus intake is down at exhaust level, so the air sucked into a car/bus includes loads of what the vehicle in front has spewed out.
But yes, mad to preach to bus riders!
It's completely grim. I'm as unallergic a person as can be, but my nose now runs constantly in London.
I want Sadiq Khan to close all roads that go past schools to everything other than buses and emergency vehicles; and in v short order to completely ban any vehicle that doesn't have an automatic cut-off when stationary. I was at traffic lights earlier today (on my bike) and there was a great throbbing motorcycle a few metres away - leaving aside the smell, just the NOISE was horrible.