New electric buses have taken to the roads in Leeds in a "huge step forward" for the network, transport bosses said.
Fifty-seven battery-powered buses have entered service, with a range of up to 200 miles (322km) between charges.
West Yorkshire Combined Authority (WYCA) said it was part of a plan to have a fully zero-emission bus fleet throughout West Yorkshire by 2038.
Road traffic has been identified as a major source of air pollution in Leeds and Bradford.
Each electric bus costs around £350,000 with the whole project requiring £29m of funding, WYCA said.
Money for the switch-over from diesel to electric buses has come from both First Bus and the UK government.
'Another major step'
Andrew Cullen, Managing Director of First Bus in West Yorkshire, said: "Today marks another major step in the First Bus strategy to expand more zero-emission buses into communities in West Yorkshire and the country, as part of our mission to reach a zero-emission UK bus fleet by 2035."
He added: "Having more of these buses on our roads will benefit areas affected by low air quality, as well as helping us to achieve our target of becoming a net-zero carbon region by 2038."
The WYCA aims for buses across all operators to be emissions-free by 2038.
The new buses, which can be charged in two-and-a-half hours, have been manufactured by Wrightbus in Northern Ireland and feature audio-visual next stop technology and USB charging points.
Deputy Chair of WYCA's Transport Committee, Councillor Peter Carlill, said: "Work to electrify the Bramley bus depot is a huge step forward for the combined authority's vision of a green, zero-emission bus system for West Yorkshire."
Double deckers are expected to join the fleet of single-decker buses in the summer.
www.firstbus.co.uk
