Some ideas that have been done or are being considered are.Two things spring to mind.
A. due to the lockdown there have been a lot less vehicle miles and so pollution has dropped
B. just how do they think the local council will be able to reduce pollution, close all factories, close the county off from the rest of the county, stop the wind blowing from the west.
Banning diesel vehicles at set times.
Congestion charges for some vehicles.
A move to natural gas powered buses.
A move to increase electrification of vehicles.
Banning vehicles from some areas.
Increasing cycle use.
Increasing cycle lanes.
Reducing air flights.