Bradford Council has been given a year to submit plans to reduce air pollution around the district’s busiest roads.
The Department for Environment, Food and Rural Affairs believed Bradford would be able to bring pollution levels to a legal limit by 2021.
However, a feasibility study has revealed that nitrogen dioxide levels on some roads would not meet a level of compliance for some time after.
These roads include the A650 in Shipley, where legal levels will not be reached until 2027, and Shipley Airedale Road in the city centre will not reach legal levels until 2024.
Bradford Council has been issued with a Ministerial Direction to come up with a more detailed plan of how to reduce air pollution by October 2019.
Similar requirements have been made in over 50 other towns and cities including Manchester and Sheffield.