Buses that filter air pollution are to be rolled out to six more towns and cities in England.
Transport firm Go-Ahead's Air Filtering Buses have three fans on the roof that strip pollutant particles from the air as they drive.
Each single-decker has three fans on the roof that suck ultra-fine particles and dirt into filters.
A trial of the technology in Southampton last year saw as much as 65g of pollutants - equivalent to the weight of a tennis ball - removed from the air in a 100-day period, Go-Ahead said.
A further five buses will be deployed in the city by early next month.
The buses will also be introduced to Brighton, Manchester, Newcastle, Oxford, Plymouth and Crawley from this summer.
Go-Ahead chief executive David Brown said: "We want to play our part in tackling the crisis in urban air quality and show that buses can be integral to cleaning up our cities.
"Our air-filtering system has exceeded all expectations in how it can benefit the environment, and it builds on our track record as operator of the UK's greenest bus fleet.
"We believe the Air Filtering Bus provides a quick win for councils as they explore initiatives such as Clean Air Zones to tackle toxic pollution."
