What is a Clean Air Zone (CAZ)?

To reduce harmful emissions and improve air quality across the UK, certain local authorities have been enforcing Clean Air Zones (CAZ) within their cities. In this blog, we explain everything you need to know about Clean Air Zones in the UK.

What is a CAZ zone?

A Clean Air Zone is an area of a town or city which enforces vehicle emission regulations on traffic travelling in and around that area. When driving in a CAZ, your vehicle must meet specific emission standards or you will face a charge. The minimum emission standards for Clean Air Zones in the UK are:

• Euro VI – Buses, coaches and HGVs
• Euro 6 (diesel) - Vans, minibuses, taxis, private hire vehicles, cars
• Euro 4 (petrol) - Vans, minibuses, taxis, private hire vehicles, cars
• Euro 3 – Motorcycles

Types of Clean Air Zones

There are four main classes of Clean Air Zones in the UK, class A through to D. The classes refer to which type of vehicle the CAZ applies to, A being the least stringent and D being the most stringent.

This means that not all cities charge private cars for driving within a CAZ. Bath and Southampton only charge commercial vehicles, including HGVs and taxis. It’s important to check the terms and conditions of the specific CAZ location as they vary by city.

How do Clean Air Zones work?

In the UK, emissions are being targeted in a few different cities. These are also referred to as ‘Clean Air Zones’ (CAZs) and can be found in England in the following cities:

The idea behind CAZs is to discourage motorists from driving in largely populated areas with highly polluting vehicles. They work similarly to Low Emissions Zones (LEZ) in Scotland, but are slightly different than the Ultra-Low Emissions Zone (ULEZ) found in London. Although, still classed as a Clean Air Zone, London’s ULEZ is far more severe. At Arnold Clark, we also stock ULEZ-compliant cars for sale

Which cities have Clean Air Zones?

Clean Air Zones can be found in a few different cities across the UK. In the below table, you can see where each CAZ is located, the area size in square miles and which CAZ class the location is.

N.B. Greater Manchester's CAZ is currently under review by the local authority and the government.

What is CAZ compliant?

Being CAZ compliant refers to vehicles which meet the minimum emission standards to drive in Clean Air Zones without incurring a charge. It's important to note that all electric cars are CAZ compliant. As mentioned above, vehicles which meet the below criteria will be able to drive in any of the CAZ cities free of charge:

• Euro VI – Buses, coaches and HGVs
• Euro 6 (diesel) - Vans, minibuses, taxis, private hire vehicles, cars
• Euro 4 (petrol) - Vans, minibuses, taxis, private hire vehicles, cars
• Euro 3 – Motorcycles

For example, if you are driving a petrol or petrol hybrid car in Bristol or Birmingham, which are Class D Clean Air Zones, your vehicle must meet Euro 4 emission standards to drive in specified areas without facing a CAZ charge.

How to pay for Clean Air Zone charges

You can pay for Clean Air Zone charges by heading to the government website. The charges are different depending on which city you are driving in, so we have broken down the CAZ cities, their classes and the charges for small vehicles, taxis and large vehicles below.

You must pay a CAZ charge by 11:59pm on the sixth day after driving into the zone. You can also pay in advance if you know you will be driving in a CAZ. If you fail to pay the charge before 11:59pm on the sixth day, you will incur a penalty charge notice (PCN).

Do Clean Air Zones work? We looked at the science

Generally, Clean Air Zones are effective in reducing harmful nitrogen oxide (NOx) emissions and particulate matter (PM) from the air as research would indicate ^[1]. A study conducted in Birmingham found that in the six months after the CAZ was implemented in 2021, NO2 levels decreased by 13% when compared to data from 2019 ^[2].

This study also found that the level of CAZ-compliant vehicles in the area had increased by 79.8% from June 2021 – December 2021 ^[2]. This proves that not only does a CAZ work by improving air quality, but also through encouraging the public to purchase less polluting vehicles. There are other cities across Europe which have implemented similar CAZ schemes, including Paris, Berlin and Amsterdam.

Your questions answered

What cars are exempt rom the Clean Air Zone?

Cars exempt from Clean Air Zone charges include:

• Euro 4 petrol cars
• Euro 4 petrol hybrid cars
• Euro 6 diesel cars
• Euro 6 diesel hybrid cars
• Electric cars

How many Clean Air Zone are there in the UK?

In the UK, as of the date of this publication, there are currently seven active Clean Air Zones. Greater Manchester’s is currently under review by the local authority and government. This number does not include Scotland’s Low Emission Zones which are located in Aberdeen, Dundee, Glasgow and Edinburgh.

What happens if you don’t pay Clean Air Zone charge?

If you don’t pay a CAZ charge by 11:59pm on the sixth day after driving in the zone, you may receive a PCN. Terms and conditions for PCNs differ depending on which city’s CAZ you have driven in.

How long do you to pay Clean Air Zone charges?

From the day that you have driven in the CAZ, you have six days to pay the charge.

What happens if you live in a Clean Air Zone?

The same rules apply; if your vehicle does not meet the minimum emission standards for the area, you will be subject to the CAZ charge. There are, however, some exemptions to this, so you should contact your local authority for more specific information on exemptions, permits and anything else.

References

1. https://www.cbi.org.uk/articles/cleaner-air-in-cities-benefits-health-and-the-economy/
2. https://www.birmingham.gov.uk/news/article/1086/clean_air_zone_interim_report_provides_evidence_of_impact_on_air_pollution