I don't know whether I'll have time with my question to go into all that.
The next question I would have, if you accept that there are a number of different things that cause these pollutants, is that some of them are okay because they're less dangerous but are perhaps more prevalent. There's that aspect as well. You might have a smokestack, but if it's scrubbed and some of this is taken out, there's less per unit of air than there is for people in a situation on a street with a lot of pollution going by them from vehicles.
Can you say emphatically that volume is also an issue with pollution?