The charge levied at drivers wanting to drive through London may have cleared roads, but the £8 toll has done little for the air.
A new study has found that levels of pollution in the city's congestion charging zone changed little before and after the city implemented the toll. Some pollutants even rose.
London congestion charge did not improve air quality
In 2003, London began hitting drivers with a £5 toll to enter a 21 square kilometre patch of the city centre. The toll has since increased to £8. By 2006, the number of cars on the road had fallen by a fifth, while the number of public buses – exempted from the toll – jumped by 25%.
"The scheme never really had air quality or people's health in mind," says Kelly. But to gauge whether the fee might improve the air, his team collected air quality measurements over two years before and after London began levying the charge.
Kelly's team noticed little change in pollutants such as smog, diesel soot, and carbon monoxide. Levels of nitrogen oxides increased slightly – Kelly thinks this was because of filters on diesel buses that trap soot, yet spew out the gases.