Clean Air Zones (LEZ, CAZ & ULEZ) explained: what UK drivers need to know

Low Emission Zones and Clean Air Zones are now common in UK cities. If your car is older or more polluting, you may need to pay a daily charge to drive through certain areas.

This guide explains the difference between LEZ, CAZ, ULEZ and ZEZ schemes, how to check your vehicle, and what drivers should do before travelling into a charging zone.

Quick summary (TL;DR)

• Clean Air / Low Emission Zones charge older, higher-polluting vehicles.
• Most zones use Euro standards to decide who pays.
• Diesel cars usually need Euro 6, petrol cars Euro 4 to avoid charges.
• Rules vary by city, so always check your reg before travelling.

LEZ, CAZ, ULEZ or ZEZ: what’s the difference?

These terms are often used interchangeably, but they’re not all the same. Here’s a simple breakdown:

What Euro emissions standard do I need?

Most zones use Euro standards to decide whether you pay.

• Diesel vehicles: usually need to be Euro 6 to avoid charges.
• Petrol vehicles: usually need to be Euro 4 or newer.

These standards roughly align with newer vehicles (diesel from ~2015/16 onward, petrol from ~2005/06 onward), but it’s always best to check your specific registration.

How to check if your car is compliant

Before driving into any low-emission or clean-air zone:

1. Get your registration number.
2. Use the official government checker for Clean Air Zones in England.
3. If travelling in London, use TfL’s ULEZ vehicle checker.
4. If your vehicle is not compliant, check the rules, charges and payment deadlines for that city.

Always use official payment sites to avoid scams.

London’s ULEZ and LEZ (2025)

London has two main schemes:

• ULEZ: Expanded across all London boroughs on 29 August 2023. Non-compliant vehicles pay a daily charge.
• London LEZ: Covers most of Greater London and applies mainly to HGVs, buses and coaches, rather than private cars.

Note: The Congestion Charge is separate from ULEZ. From January 2026, electric cars will no longer be fully exempt from the Congestion Charge (they’ll get a discount instead).

Which UK cities have charging zones?

Charging schemes are set locally, and rules can change. Major examples include:

• Birmingham CAZ (operational since 2021).
• Bristol CAZ (started 28 Nov 2022).
• Glasgow LEZ (fully enforced since 1 June 2023).
• Oxford ZEZ pilot (city-centre streets).

Because coverage and charges vary, always check your route and vehicle compliance before travelling.

CAZ classes A–D explained

In England, Clean Air Zones are grouped into classes:

• Class A: Charges buses, coaches, taxis and private hire vehicles.
• Class B: Class A + HGVs.
• Class C: Class B + vans and minibuses.
• Class D: Class C + private cars (not every city uses Class D).

You may still be exempt or discounted depending on your city and vehicle type.

Why were these zones introduced?

Air pollution in urban areas is linked with health conditions including asthma and heart disease. Older diesel vehicles are a major source of nitrogen oxides and particulate matter, which are especially harmful in dense city centres.

Clean Air and Low Emission Zones aim to reduce these pollutants by encouraging cleaner vehicles and alternative transport.

How will LEZ and CAZ affect drivers?

If your vehicle meets the required Euro standard, you can usually drive through without paying. If not, you must pay the daily charge for that city.

Charges vary widely by location and vehicle class, so checking ahead is essential. Repeat non-payment can lead to penalty notices.

What else can drivers do?

If you’re not ready to change vehicle yet, you can still reduce emissions and running costs:

• Drive less where possible (car share, walk, cycle or combine trips).
• Drive smoothly to reduce fuel use and emissions.
• Keep tyres properly inflated to lower rolling resistance.
• Plan routes to avoid zones if your vehicle isn’t compliant.

Find tyres for your vehicle at Blackcircles if you’re due a replacement.