We look at which cities have introduced a Clean Air Zone (CAZ), whether you have to pay to enter a CAZ and how you can get a compliant vehicle.

What Is A Clean Air Zone (CAZ)?

A Clean Air Zone (CAZ) is an area where a local authority is taking action to improve air quality.

In some cities, drivers have to pay to enter a CAZ if their vehicle isn't compliant. This is known as a 'charging CAZ'. In other cities, non-compliant vehicles are not allowed to enter a CAZ and are fined if they do so.

Non-compliant vehicles are typically pre-Euro 4 petrol and pre-Euro 6 diesel.

But it's a bit more complicated than that, as there are four types of CAZ (Class A to D), which the Government has said local authorities can introduce:

A - Buses, coaches, taxis, private hire vehicles
B - Buses, coaches, taxis, private hire vehicles, heavy goods vehicles
C - Buses, coaches, taxis, private hire vehicles, heavy goods vehicles, vans, minibuses
D - Buses, coaches, taxis, private hire vehicles, heavy goods vehicles, vans, minibuses, cars, the local authority has the option to include motorcycles


Some cities, such as Bath, have chosen to introduce a Class C CAZ, while others, such as Birmingham, have opted for a Class D CAZ.

This means it's OK to drive a pre-Euro 4 petrol car in Bath’s CAZ, but in Birmingham, you'll need to pay a daily charge to enter its CAZ. 

London has an Ultra-Low Emission Zone (ULEZ), which applies to cars, motorcycles, vans and specialist vehicles (up to and including 3.5 tonnes) and minibuses (up to and including 5 tonnes).

Oxford has gone further than the minimum CO2 emissions standard. It is trialling a Zero Emission Zone (ZEV), where only vehicles with zero tailpipe emissions can enter without paying a charge.

There are also exemptions and grace periods in place in some cities so it's important to understand the rules for each.

Which Cities Have CAZ?

How do I check if my vehicle is compliant?

Check vehicle compliance for the London ULEZ here

Check vehicle compliance for Clean Air Zones in England here

If you're a business and you need to check multiple vehicles, you can create an account and upload a spreadsheet in CSV format of the number plates (registration numbers) of the vehicles you want to check.

National exemptions are also in place for CAZs in England, if you have a:

  • ultra-low emission vehicle
  • disabled passenger tax class vehicle
  • disabled tax class vehicle
  • military vehicle
  • historic vehicle
  • vehicle retrofitted with technology accredited by the Clean Vehicle Retrofit Accreditation Scheme (CVRAS)
  • particular agricultural vehicle

Check vehicle compliance for Low Emission Zones in Scotland here

National exemptions are also in place for LEZs in Scotland. These include:

  • Vehicles for people with disabilities, including people who have Blue Badges
  • Historic vehicles
  • Emergency vehicles
  • Military vehicles
  • Showman’s vehicles

Find out more on the national LEZ page.

What is a Clean Air Zone (CAZ)?

At SOGO, we're pleased to tell you that all of the vehicles on our fleet are compliant with the London ULEZ, England’s CAZs and Scotland’s LEZs.

We also have a range of fully electric vehicles to meet the Oxford ZEZ.

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