The Environment Committee met on Wednesday morning. Following my return to this body, I'm still finding my feet and coming to terms with the often rather scientific evidence we receive.
This meeting was no exception, with witnesses from King's College London and the AEA, giving us their take on the problems of air pollution.
The Dirty Man of Europe
London is often criticised for its air quality, and there is a very real threat of a fine from the European Union if things don't improve. I find the finger pointing a little surprising - back in July I spent two weeks in Sorrento and when I got off the plane at Naples, I can't say that I was struck by the cleanliness of the air... So I asked if other European cities were going to face fines too.
The experts told us that Paris, Berlin, Rome and most other European cities also have poor air quality and it is getting worse. However London is top of the pollution league because it is so much larger. So is the proposed fine in effect a tax on the size of our city rather than its air quality? Have those cunning Europeans put one over our hapless government and created another way to redistribute our wealth?
I'm never happy to see public sector organisations fined punitively, because of course the punishment isn't real - except for the taxpayer who has to foot the bill.
Poisons in the Air
There are two forms of pollution that we measure to determine air quality:
Nitrogen Dioxide is a waste product of vehicle engines and industrial processes. In high concentrations it is highly poisonous and at lower levels it has harmful effects. Over 90% of the residents of Westminster and Kensington & Chelsea are exposed to dangerous levels of nitrogen dioxide. In Camden and Islington this figure is over 50%.
Particulates, known as PM10s, form a very fine dust, and are produced by vehicle engines. If - like me - you live near a main road or a busy car park, you can see particulates in the greasy film of dirt on your windows. Breathing that in can't be very healthy, and PM10s are known to irritate the lungs, aggravating existing conditions.
Ozone, a third pollutant, is not measured but the experts think it should be. Made up of three oxygen molecules, ozone is produced naturally when pollution combines with bright sunlight. Unlike ordinary oxygen, ozone is poisonous.
And here is an interesting fact - Diesel engines produce nearly twice as much nitrogen dioxide as petrol engines. They produce 17 times more particulates!
Professor Frank Kelly of King's College was critical of recent policies that have encouraged a switch from petrol to diesel fuelled vehicles. Of course petrol engines produce more carbon dioxide, which causes global warming, hence the move away from them.
Whilst Saving the World, we have been poisoning ourselves!
The verdict - diesel vehicles should be encouraged in the country but in London petrol is less harmful and alternative fuels, even electric vehicles, should be the ultimate aim.
Speed v Health
We also heard that slow moving traffic pollutes more than a free flow of vehicles. Of course we don't need science to tell us that - just stand close to any queue of cars and watch the smoke pour out whilst they go nowhere.
But science has produced an interesting figure. Vehicles travelling at speeds over 20mph produce half as much pollution.
So road humps harm air quality, as do excessive numbers of traffic lights and other artificial delaying measures so beloved of local councils. The longer the hold up, the worse the air quality. The trade off between road safety and air quality is not as straightforward as was thought at one time.
With Green members promoting 20mph zones for the whole city, this fact was clearly an inconvenient truth.
With the contentious detail dealt with, the committee welcomed Kulveer Ranger, Richmond Cllr Stephen Knight and veteran campaigner John Stewart, to update us on the Heathrow proposal. With opposition now everyone's policy - even Labour disagree with Gordon Brown - a healthy degree of consensus broke out.
The councils are planning unspecified legal action, with support from the mayor's office, but with detailed plans expected in two years, this one will be decided by a new government. we will hear a lot more about Heathrow as the general election approaches...