There is a growing mood in favour of cleaner air. There is general agreement that the air in city centres like London needs urgent action to clean it up. In the centres of our Thames Valley towns there is also room for improvement. Some are already blaming the diesel car as the main cause and urging higher taxes or bans on diesel vehicles. It is a good idea first to examine what we know about the sources and causes of pollution.
The London Assembly researched the sources of Nox in London in 2015. This showed the following sources
Bus, coach and rail public transport 18%
Goods vehicles 17%
Gas heating systems 16%
Non road mobile machinery 14%
Diesel cars 11%
Petrol cars and motorcycles 8%
Aviation 8%
Industry 7%
The TFL study in 2016 showed a similar pattern, with gas heating and industry as the biggest source, and with both bus and coach and goods vehicles each a bit bigger than diesel cars.
The new Euro VI standards for engines require both petrol and diesel engines to emit less than 5mg per km of particulates. They allow just 80 mg of Nox for diesels compared to 60 mg for petrol, whilst allowing petrol engines to emit more carbon monoxide than diesels (100mg versus 50mg)
In order to clean up the air, especially removing particulates, requires replacement of a lot of older technology buses, trains, cars, and gas boilers. This will also allow the introduction of equipment which is more fuel efficient, also helping to drive down emissions and cut running costs.
Instead of working up a new series of penalties for owners of older diesel cars, government should work on a range of incentives to tackle the problem in a broad based way, removing the oldest buses, lorries, cars and boilers which would do the most to improve the position. it could also give a welcome boost to the home industries that produce these items.
We should not ignore the contribution replacing old heating boilers at home and work can have, with the added bonus of cutting running costs. Lets have better scrappage and financing schemes, so more people can afford to make their contribution to cleaner air, and can at the same time take pride in owning better machines.
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