What is a Clear Air Zone?
A Clean Air Zone (CAZ) is a designated area where measures are in place to reduce air
pollution. Local authorities establish CAZs to improve air quality by discouraging the use of high-emission vehicles. Some CAZs charge non-compliant vehicles a daily fee, while others focus on non-charging policies such as encouraging environmentally friendlier transport options.
There are mainly 4 different classifications of CAZ:
Class A: Buses, coaches, taxis, private hire vehicles
Class B: Buses, coaches, taxis, private hire vehicles, heavy goods vehicles
Class C: Buses, coaches, taxis, private hire vehicles, heavy goods vehicles, vans, minibuses
Class D: Buses, coaches, taxis, private hire vehicles, heavy goods vehicles, vans, minibuses, cars, the local authority has the option to include motorcycles
Each type of vehicle has a minimum emission standard as well:
Buses, coaches, heavy goods vehicles: Euro VI
Vans, minibuses, taxis, private hire vehicles, cars: Euro 6 (diesel) and Euro 4 (petrol)
Motorcycles: Euro 3
These zones operate every day of the year, 24 hours a day, 7 days a week. Charges must be paid by 11:59 PM on the sixth day after driving into the zone. The payment can also be made 6 days before your trip. If you do not pay the charge in this time, you may get a penalty charge notice (PCN).
For business owners, businesses that own or manage 2 or more UK registered vehicles can set up an account to check and pay charges for multiple vehicles. You can create an account when you check or pay online.
What is an Ultra Low Emission Zone?
An Ultra Low Emission Zone or ULEZ is a similar type of air pollution control zone implemented specifically in London. Unlike CAZ, which can apply to multiple cities with different policies, ULEZ follows a uniform standard within the Greater London area.
ULEZ, contrary to CAZ, only operates in the Greater London area, applies 24/7, every day of the year except Christmas Day. Charges apply to vehicles that do not meet Euro 4 (petrol) or Euro 6 (diesel) emission standards. Non-compliant vehicles face a £12.50 daily charge for cars, motorcycles, and vans up to 3.5 tonnes; heavier vehicles incur higher fees.
Is my car ULEZ or CAZ compliant?
Some vehicles are exempt from paying the charge:
- Fully electric vehicles (EV)
- a vehicle that’s ultra low emission
- a disabled passenger tax class vehicle
- a disabled tax class vehicle
- a military vehicle
- a historic vehicle
- a vehicle retrofitted with technology accredited by the Clean Vehicle Retrofit
Accreditation Scheme (CVRAS)
However, it is important to note that the London congestion charge exemption for EVs will expire in December 2025. Additional exemptions can be found on the Transport for London homepage.
To summarise, CAZ and ULEZ are both measures put in place by the government to discourage the use of high emission vehicles. The table below concisely outlines the key differences of these two concepts.
