What is the difference between LEZ, ULEZ & CAZ?

With discussions over climate change ramping up in recent years, countries around the world are taking action to positively affect the environment for future generations.

Various areas across the UK have had their motoring lives changed recently following the inclusions of Low Emission Zones (LEZ), Ultra-low Emission Zones (ULEZ), and Clean Air Zones (CAZ).

The reasoning for these zones being implemented is to reduce pollution caused by vehicles, including nitrogen oxides (NOx) and particulate matter (PM).

So, what does this mean for certain areas in the UK? And what are the differences between these three zones? That’s what we will cover in this article today.

What is a Low Emission Zone?

A Low Emission Zone (LEZ) is an area where restrictions are imposed upon the highest polluting vehicles.

These LEZs have been imposed across the UK recent years, with London being the first city introduced to a Low Emission Zone in 2008.

Since then, 10 areas in the United Kingdom have been introduced to Low Emission Zones, including locations such as Edinburgh, Portsmouth, and Glasgow implementing the LEZ rules.

These rules consist of cars needing to meet certain emission standards, which are as follows:

• Euro 4 for petrol cars and vans - typically vehicles registered from 2006
• Euro 6 for diesel cars and vans  - typically vehicles registered from September 2015
• Euro 6 for petrol and diesel taxis and private hire vehicles, according to standard licence conditions, as set out in the Taxi Emission Standards Policy (2021)
• Euro VI for buses, coaches, and HGVs – typically vehicles registered from January 2013

If these standards are not met, the penalty charge notice (PCN) are:

Non-compliant cars, vans, and special purpose vehicles

• £60 initial PCN (Penalty Charge Notice) per vehicle – if paid within 14 days, reduced to a £30 fine
• £120 PCN upon the second breach if the same vehicle has been driven again within 90 days of first breach
• £240 PCN upon the third breach if the same vehicle has been driven a third time within 90 days of first breach
• £480 PCN upon the fourth breach if the same vehicle has been driven a fourth time within 90 days of first breach

Non-compliant minibuses, buses / coaches, and heavy goods vehicles

• £60 initial PCN per vehicle – if paid within 14 days, reduced to a £30 fine
• £120 PCN upon the second breach if the same vehicle has been driven again within 90 days of first breach
• £240 PCN upon the third breach if the same vehicle has been driven a third time within 90 days of first breach
• £480 PCN upon the fourth breach if the same vehicle has been driven a fourth time within 90 days of first breach
• £960 PCN upon the fifth breach if the same vehicle has been driven a fifth time within 90 days of first breach

LEZ Vehicle Exemptions

• Vehicles for people with disabilities (blue badges)
• Historic vehicles
• Showman’s vehicles
• Emergency vehicles
• Military vehicles

What is an Ultra Low Emission Zone?

An Ultra Low Emission Zone (ULEZ) is an area in which strict policies are enforced to help tackle emission pollutants.

The purpose of ULEZ is the same as LEZ, however, stricter rules and regulations and in place when it comes to the vehicles being targeted.

As it relates to the UK, only London have an Ultra Low Emission Zone, with the introduction of the zone being in April 2019. ULEZ was eventually expanded to all London boroughs in August 2023.

The rules of ULEZ in London are as follows:

• Euro 3 (Cars registered from 1st January 2001) – NOx emissions limit of 500mg/km for diesel, 150mg/km for petrol
• Euro 4 (Cars registered from 1st January 2006) – NOx emissions limit of 250mg/km for diesel, 80mg/km for petrol
• Euro 6 (Cars registered from 1st September 2015) – NOx emissions limit of 80mg/km for diesel, 60mg/km for petrol

The charges are a little more straightforward than LEZ charges, with a daily £12.50 charge being applied every time a non-compliant vehicle is driven within the zone.

Failure to pay the charge by midnight on the third day following the journey or up to 90 days in advance will increase the risk of getting a further Penalty Charge Notice.

What is a Clean Air Zone?

Clean Air Zones (CAZs) are more or less what both ULEZ and LEZs are – areas that have rules & regulations to tackle emission pollutant vehicles. Both LEZ and ULEZ are considered as Clean Air Zones.

Most CAZs are in effect 24/7, with Clean Air Zones being in the following UK cities:

• Aberdeen
• Bath
• Birmingham
• Bradford
• Bristol
• Dundee
• Edinburgh
• Glasgow
• London
• Newcastle
• Oxford
• Portsmouth
• Sheffield
• Southampton

What is the difference between LEZ and ULEZ?

The difference between LEZ and ULEZ is the stricter rules that are implemented by ULEZ.

ULEZ target a significant reduction in air pollution with their regulations targeting a broader range of vehicles. Although LEZ targets various vehicle types, ULEZ targets more types of vehicles and is aimed at petrol and diesel vehicles that don’t meet the Euro 4 and Euro 6 vehicle standards.

What is the difference between LEZ and CAZ?

There isn’t any real difference between LEZ and CAZ, as a Low Emission Zone is regarded as a Clean Air Zone.

Clean Air Zones are areas in which there are policies in place to tackle emission polluting vehicles. This makes Low Emission Zones being defined as Clean Air Zones, as areas with a LEZ are tackling air pollution.

What is the difference between ULEZ and CAZ?

Much like the comparison of LEZ and CAZ, there is no difference between a ULEZ and CAZ.

ULEZ is a Clean Air Zone, as an Ultra Low Emission Zone is an area in which air pollution is being improved through rules & regulations implemented.