Wandsworth Council’s transport spokesperson is calling on the Mayor of London to "explain why polluting buses have not been withdrawn" from the borough.

Mayor Sadiq Khan announced in March that Putney would be the first Low Emission Bus Zone in a bid to "tackle toxic air".

See related: Mayor of London Sadiq Khan announces Putney to be first Low Emission Bus Zone

The clean bus zone would be serviced by cleaner buses.

However, the older, more polluting buses have merely been switched with buses on other routes nearby.

Modern, cleaner buses with Euro 6 diesel engines that were being used on the G1 route that runs from Streatham to Battersea via Tooting and Clapham Junction have been moved to the clean zone and replaced by the more polluting buses.

The transport, as well as environment, spokesman Councillor Jonathan Cook said: "If highly polluting buses are being shifted to other routes to achieve a clean bus zone then the Mayor should be open and honest about it.

"He was quite clear in what he said. He was going to 'remove the oldest and dirtiest buses from our streets' but instead they have just been switched to nearby neighbourhoods so they can belch out noxious fumes there instead.

"And just days after saying all dirty diesel vehicles should be banned from going anywhere near schools these obsolete and polluting buses have been diverted to run past lots more schools and nurseries.

"As a result of this change air quality will be made worse in Battersea, Tooting and Streatham. Simply spreading pollution around is no solution for London."

Leon Daniels, TfL’s managing director of Surface Transport, said: "Of the nearly 150 buses that use Putney High Street, around half have recently been replaced as part of our work to improve air quality with Low Emission Bus Zones that will reduce local harmful emissions by over 80 per cent.

"Of the remaining buses, the majority already met the highest Euro VI emissions standard, but around 30 vehicles need to be retrofitted with an improved exhaust system to meet the standard. 

"This is taking a little longer than originally thought, so whilst these buses are retrofitted, there is a short term movement of these vehicles to routes outside of Putney.

"I apologise for the delay. All buses moved from Putney will be fully retrofitted as soon as possible."

Residents in the Shaftesbury Park Estate, served by the G1 route, contacted Cllr Cook when they noticed the buses passing by were considerably older and emitting more fumes than usual.

He said: "It’s a dreadful way for people to find out as it makes it look like TfL tried to get away with it without anyone noticing."

Cllr Cook stressed he did not want to sound too negative as Wandsworth Council has done "massive amounts" to improve air quality, but that it was "disappointing" they had not been told about the decision to switch the buses instead of removing them completely.