London's pollution is exacerbated by London buses travelling at snail paces due to growing congestion, a new report has suggested.
A report by Professor David Begg, a former chairman of the government's Commission for Integrated Transport, pointed to some routes "close to walking speed" that mean buses chug out more fumes.
"Fuel efficiency measured in kilometres per litre has declined by 35 per cent since 2000, and carbon dioxide emissions per bus km in urban conditions have risen by 25 per cent," Begg wrote.
"While there are factors other than congestion driving this trend, such as larger buses, stop-start conditions caused by congestion are a key factor. Under heavily congested conditions, tailpipe emissions can be increased by a factor of three or four."
The report looks at worsening conditions for the bus sector that "has become a crisis for the capital and something the new mayor, Sadiq Khan, must prioritise".
It added that online shopping and Uber had caused problems for the bus sector as they have created alternative traffic, while cycle superhighways had created problems for congestion as road space had reduced without anything to compensate by reducing traffic.
"[Boris Johnson] went against the advice of TfL by implementing Cycling Superhighways without reducing traffic volumes in central London. You can’t take 25 per cent of road space out on key routes in central London without doing anything to compensate by reducing traffic. The result has been worsening congestion and slower traffic speeds. Bus passengers have been the main losers," Begg said.
Mayor of London Sadiq Khan has already been active in the bus sector by introducing a one-hour hopper fare, which could mean more journeys taken on buses.
He has also launched a consultation to tackle air pollution in the capital, with proposals including the implementation of an extra charge on the most polluting vehicles entering London.