Drivers of so-called dirty vehicles in Bristol could be forced to pay a charge to drive into the city centre.
There are plans to create a Clean Air Zone in the city in a bid to cut down on pollution.
Taxi drivers have been warned they may have to pay a daily fee - but the charges would also apply to other motorists.
Which vehicles could be affected?
The most likely cars to be incorporated under the charge includes:
private hire vehicles
diesel cars made before last year
petrol cars made before January 2005
Why is the charge being considered?
Air pollution is killing more than 200 people a year in Bristol - according to government data.
The city's air quality is illegally low - and European politicians say tougher laws are needed.
A similar low-emission scheme covers most of London.