CAZ
Clean Air Zones are local clean-air charging areas run by councils outside London. Birmingham, Bath and Bristol operate Class D zones that charge non-compliant private cars — using similar Euro 4 petrol / Euro 6 diesel thresholds to London’s ULEZ but with their own daily charges and exemptions. Other cities target buses, taxis and lorries rather than cars. Always check the specific city’s rules on the GOV.UK vehicle checker before you travel.
Example
Birmingham’s CAZ charges non-compliant cars £8 a day; Bath charges £9 and Bristol £9, each with different exemption schemes.