Transport for London (TfL) has announced that 300 low emission buses will be introduced into the London public transport fleet before the end of 2014.
The new buses make up almost half of the 700 buses to join London’s system in 2014, and have the latest Euro VI engines (link is external) to meet the European standards on emissions from heavy-duty vehicles. These buses were found by TfL to produce 95 per cent fewer nitrogen oxide (NOx) emissions than engines meeting lower standards.
These buses complement the roll-out of hybrid buses across the city, nearly 1 000 of which are already on London’s roads. A total of 1 700 are due to be in operation by 2016, making up approximately 20 per cent of the city’s total bus fleet.
‘Improving London’s air quality is one of the Mayor’s top priorities, and by 2020 all buses in central London will be either hybrid or electric as we look to radically cut emissions,’ said Matthew Pencharz, the Mayor’s Senior Advisor for Environment and Energy.
Under the London Ultra Low Emission Zone (ULEZ) proposal, all buses driving in central London from 2020 will need to meet the Euro VI standard for NOx emissions. 
Original author: Alexia