A $21.5 million grant from the Federal Transportation Administration will allow Tucson to purchase 39 compressed natural gas buses, according to a news release from the city.

The buses will replace the diesel fuel buses that remain in Sun Trans fleet. The move is expected to reduce carbon dioxide emissions by 2,480 metric tons, the release said.

In addition to the grant, Tucson will provide an additional $5.37 million for the upgrade.

Decarbonizing the transit system will be a powerful victory for our community, bringing cleaner air and a brighter future for all Tucsonans, Mayor Regina Romero said in the release.