People using the Metrolink in Greater Manchester are to be offered free travel today to mark Clean Air Day.
The idea is to encourage people to help improve the quality of air and reduce pollution in the city region.
Transport for Greater Manchester, who operate the service, say it is part of a drive to encourage people to think about changing travel habits to improve air quality.
The company is also encouraging employers to consider flexible working hours for their staff so that they can take advantage of the free travel offer.
The offer applies for anyone using the service before 7 am or after 7 pm