Drivers of diesel vehicles could face restrictions on going into city centres under Government proposals to improve air quality.
The move would affect six cities in areas where air quality targets for 2020 are expected to be missed.
They are London, Birmingham, Leeds, Nottingham, Derby and Southampton.
The consultation document, launched by the Department for Environment, Food and Rural Affairs, states that local authorities in these cities should "consider the role of access restrictions for certain types of vehicles" to reduce nitrogen dioxide (NO2) emissions.
NO2 is estimated to be responsible for 23,500 deaths in the UK each year, while a further 29,000 are killed by particulates - which are tiny particles of soot.
Mayor of London Boris Johnson has already announced plans for an "ultra-low emission zone" in the capital from 2020.
The move will require all but the cleanest diesel cars already manufactured to pay an extra £12.50 each day they enter the congestion charge zone, on top of the standard fee (currently £11.50).