UK low emissions zones (LEZ) and Clean Air Zones (CAZ): what to know

April 18, 2023 by

Low Emissions Zones are being introduced across the UK. What are they and how will they affect drivers? Read on to find out.

A Low Emissions Zone, often referred to as a LEZ or sometimes a CAZ (Clean Air Zone – the terms are used interchangeably), is inner-city area that drivers of more polluting vehicles must pay to drive through.  The aim is to encourage drivers to use newer, less polluting vehicles or make the switch to public transport.

The most well-known low-emission zones are the London ULEZ (Ultra-Low Emission Zone) and LEZ (Low Emission Zone – this one is for trucks and HGVs), although more UK cities are introducing their own clean-air zones. Here’s everything you need to know.

Why have LEZ and CAZ been introduced?

We’ve learnt a lot about air pollution in the last 20 years or so, with growing evidence indicating the exhaust fumes from older diesel cars being particularly harmful to human health. Nitrogen oxides and particulate matter – the latter essentially being microscopic pieces of soot – are linked to everything from heart disease to asthma, and are prevalent in untreated diesel exhaust fumes. When heavy traffic combines with dense populations – IE in towns and cities – these emissions build up in the air and are breathed in by people.

Diesel cars made since around 2016 must, by law, have diesel particulate filters that trap the tiny pieces of soot; and selective catalytic reduction (SCR), which is more commonly known as AdBlue, and sees a urea-based liquid squirted into a diesel car’s exhaust gases, converting nitrogen oxides into water and nitrogen. Diesel cars have to have SCR in order to meet Euro 6 emission standards, hence why this standard has been used as the criteria for whether such a vehicle incurs a fee for entering a low-emission/clean-air zone.

Petrol cars emit more carbon dioxide than diesels, but little-to-no particulate matter and much less nitrogen oxide, hence why earlier, Euro 4 standards (introduced over 2005/6) are used as the barrier to entry for petrol cars driving into LEZs and CAZ.

For these reasons, authorities have introduced these Clean Air Zones, with Transport for London launching the ULEZ (which is an example of a CAZ) in 2017, and central Government mandating certain cities to bring in similar zones at later dates.

In addition to this, Highways England has also started to introduce temporary 60mph speed limits on several UK motorways in an attempt to reduce levels of Nitrogen Dioxide (NO2) in the surrounding areas, often near large cities.

Where are they located in the UK?


London has two zones designed to restrict the use of more polluting vehicles. The Ultra-Low Emissions Zone was expanded on 29 August 2023 to cover almost all areas inside the M25.

Vehicles that do not meet the ULEZ requirements are required to pay a charge. This is £12.50 for cars, motorcycles and vans, and £100 for heavier vehicles, including lorries over 3.5 tonnes, plus buses and coaches over 5 tonnes. Congestion Charge fees continue to apply to all vehicles, however. Petrol cars not meeting Euro 4 standards and diesels not meeting Euro 6 rules must pay the fee if they enter the ULEZ.

Our handy ULEZ checker shows you the exact boundaries of both the LEZ and ULEZ in London, and tells you whether your vehicle is ULEZ-compliant or not.
The second London emission zone is the Low Emission Zone, or LEZ. This covers most of greater London, but it only applies to HGVs, buses and coaches – not cars.
Most other emission zones in the UK do not apply to private cars – though one or two do; we’ll highlight all of these below.


Birmingham’s CAZ became operational in 2021 and covers all roads within the Middleway Ring Road. It works under similar rules to London’s ULEZ, operating 24 hours a day and seeing more polluting cars (pre Euro 4 petrols and pre Euro 6 diesels) charged £8 to drive in the zone, while non-compliant buses and lorries pay £50.


Bristol’s CAZ came into force on 28 November 2022, and sees drivers of more polluting cars charged if they enter a portion of the city centre. As with London’s ULEZ, it affects pre-Euro 4 petrol cars and pre-Euro 6 diesels, which will have to pay £9 to enter the zone. Non-compliant taxis and light vans face the same charge, while HGVs and buses pay £100.


Oxford’s Zero Emission Zone is very small, covering some or all of nine streets in the city centre, with all private cars other than electric ones having to pay £2 to £10 to enter the zone. More polluting cars (EG non Euro 6 diesels) pay the higher charges.


Glasgow city centre was the first area in Scotland to have a low emission zone introduced, and came into effect on December 31 2018. Two phases form part of the plans, with the first having covered local buses. The second sees all vehicles needing to meet Euro 4 and 6 (for petrol and diesel cars respectively) emissions, but unlike other emission zones, drivers of non-compliant vehicles can’t pay to enter in the zone, with a £60 penalty for breaching the rules, and this penalty doubling until it reaches a £480 cap, regardless of whether the initial penalty is paid or not. Glasgow’s Low Emission Zone came into force on 1 June 2023.


Bath launched its Clean Air Zone in March 2021. It doesn’t affect private cars and motorbikes, so you shouldn’t have to pay a fee if you’re driving around in your own car, though business-use vehicles like taxis and HGVs have to pay a fee if they don’t meet certain emissions standards.


Bradford’s Clean Air Zone doesn’t apply to cars, only taxis, lorries and other commercial vehicles. Taxis pay £7 to enter the zone, with HGVs and buses paying £50.


Portsmouth’s CAZ covers a small area of Portsea island. Taxis that don’t meet the respective Euro standards must pay £10 a day to enter the zone, with HGCs and buses paying £50. Private cars are not affected.

Are more coming?

ULEZ was the UK’s first low-emission zone, but as will have discerned by now, the precedent it set is being echoed across the country. The path to introducing these zones is not always smooth though.


A proposal has been made for a Clean Air Zone across Greater Manchester, which had initially been planned to be introduced in May 2022. However, this plan was rejected — with proposals for a new zone set to be consulted on in 2023.


Aberdeen introduced a Low Emissions Zone in May 2022, though enforcement  will not commence until May 2024. The following cars will be prohibited from entering the zone:

  • A pre-Euro VI diesel car (generally those registered before 2015)
  • A pre-Euro IV petrol car (generally those registered before 2006)


Similarly to Aberdeen, Dundee City Council’s LEZ was introduced in 2022, though it will not be enforced until May 2024. It follows the same vehicle rules as Aberdeen’s LEZ.


Edinburgh’s LEZ follows the same rules as the two Scottish cities above, with enforcement due to begin in June 2024.


Newcastle City Council introduced its CAZ in October 2022, and will begin to charge drivers from January 2023 – though it will only apply to older taxis, vans, buses, coaches and HGVs – private cars will not be affected.


Like other CAZ, Sheffield’s Clean Air Zone won’t affect private vehicles for the time being — though older taxis, vans and large vehicles will be subject to a charge for entering the zone, which will begin operating in June 2023. LGVs and taxis will have to pay £10 a day, with coaches, buses and HGVs subject to a £50 fee.

What vehicles are exempt from LEZ and CAZ charges?

Though many of the UK’s zones aren’t yet impacting private cars, it’s possible they will in the future.

Almost all CAZ, LEZ and ULEZ in the UK that charge private cars use Euro Emission standards as the basis for whether or not drivers have to pay. Euro standards are tightened up periodically (hence why we’re now on the sixth iteration) and they were never intended to be used in the manner they are with emission zones, instead being emission-based limits new cars have to meet before they can be sold in Europe.

Older diesel cars are relatively polluting (though systems like AdBlue mean modern ones are on a par with petrols), which is why the rules are tougher for diesels.

As a rule of thumb, expect all emission zones that affect private cars to charge pre-Euro 6 diesels and pre Euro 4 petrols.

Euro standards are introduced gradually, first applying to newly introduced models launched to the market, before applying to all new cars sold in showrooms.

As a result, it’s tricky to give precise dates for when cars are likely to meet these standards, but as a general rule if a diesel car was bought new in late 2015 and onwards it should be Euro 6 compliant, and thus exempt from emission-zone charges. For petrol cars the date is more like 2006 and onwards. In both instances, it’s possible both later and earlier cars will attract or be exempt from the charges (Euro standards were never meant to be used in this way for a reason…).

How much does it cost to enter a LEZ or CAZ?

Between nothing and £300, depending on the zone and your vehicle.

That £300 charge is for HGVs not meeting standards and driving into London’s LEZ, with most charges being much less for cars.

The table below outlines the current zones that apply to private car drivers.

Zone Charges apply to Fee
London ULEZ Pre Euro 4 petrols, pre Euro 6 diesels £12.50
Birmingham CAZ Pre Euro 4 petrols, pre Euro 6 diesels £8
Bristol CAZ Pre Euro 4 petrols, pre Euro 6 diesels £9
Oxford ZEZ All cars but electric/hydrogen ones £2-£10

If in doubt, you can use our clean air zone checker to see if your car will face any charges.


How do I pay the LEZ or CAZ charge?

Each LEZ has it’s own payment system, but it’s pretty simple to pay to enter the zones. The ULEZ, for instance, is most easily paid online via TfL’s website, although you can download the TfL app, or call a telephone helpline, while an auto-pay account (which will automatically detect your vehicle has entered the zone and take direct payment from your bank account) is worth considering if you regularly need to drive a non-compliant vehicle into the ULEZ. Payment for the Birmingham and Bristol CAZ are best made through the Government’s online portal.

Do be warned that there are a number of scam websites that look like official payment channels, sometimes even copying the distinctive black-and-white colour schemes of the Government’s official websites. These scams will purport to take payment from you (sometimes with this payment being higher than the official charge), but not actually pay the ULEZ charge, leaving you scammed out of the payment amount, as well as receiving a fine from TfL for not paying the fee to enter the zone. To avoid such scams, make sure you only use official payment channels by looking closely at the web address in the URL bar of your internet browser. TfL and the Government pages have ‘’ suffixes in their site addresses.

Can I claim VAT on the LEZ or CAZ charge?

No, these fees are non-business statutory levies, so are not within the scope of VAT. If you’re self-employed, LEZ and CAZ charges should be tax deductible if you need to pay them for reasons related to normal business travelling expenses, though.

How do I know if I’ve entered a LEZ or CAZ?

LEZs and CAZs are generally well signposted both in advance of their commencement (EG a sign may read ‘Ultra Low Emission Zone, 3 miles ahead’) and as you enter them. If you fail to spot these signs (they’re also sometimes indicated by road markings) then the first you know of the fact you’ve entered a zone might be when you receive a penalty for not paying the charge. The onus, rightly or wrongly, falls on drivers to know where these zones are, if their car is compliant, and if they have entered them.

What happens if I don’t pay the LEZ or CAZ charge?

You can pay CAZ and LEZ charges generally one day in advance, or three days in the past (EG if you entered the ULEZ on a Saturday, you have until Tuesday to pay it). Fail to do so and you will receive a penalty charge notice (PCN) from TfL, which stands at £180, reduced to £90 if paid within 14 days. Birmingham’s CAZ brings a £120 penalty for failure to pay, again, reduced by 50% if paid within 14 days.

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