Accompanying the rise in the number of people driving electric cars and in line with the upcoming UK ban on the sale of new petrol and diesel vehicles, drivers in urban areas have been experiencing the introduction of Ultra Low Emission Zones (ULEZ) and Clean Air Zones (CAZ). 

In this guide, we’re going to explain what these zones are, how they work, who they affect, who might be exempt and what drivers need to do to comply. 

What Are ULEZ and CAZ?

The ULEZ covers every borough of London as the largest clean air zone in the world, helping nine million residents breathe cleaner air. Drivers of vehicles that don't meet certain emission standards need to pay a daily charge to drive in the zone.

CAZ are Clean Air Zones that work in the same ways as the ULEZ but have been brought in by local authorities to improve air quality. These local authorities set the charges so it is worth checking to see what their rules are on non-compliant vehicles.

The goals of ULEZ and CAZ are to reduce emissions and improve air quality in cities.

Differences Between ULEZ and CAZ

ULEZ and CAZ are essentially the same, apart from they cover different geographical areas and the exact regulations and the way they are enforced are slightly different.

ULEZ covers all London boroughs and the City of London not including M25. This ULEZ checker includes a postcode checker to find out if any particular postcode is included.

CAZ zones (at time of publishing) currently include Aberdeen, Bath, Bradford, Bristol, Birmingham, Dundee, Edinburgh, Gateshead, Glasgow, Oxford, Portsmouth, Sheffield and Southampton. However, it’s worth noting that Dundee, Edinburgh, and Glasgow are officially defined as LEZ’s just to complicated matters slightly (Low Emission Zones), but the terms LEZ and CAZ are used interchangeably.

With ULEZ, most vehicles need to meet the ULEZ tailpipe emissions standards or the drivers must pay a £12.50 daily charge to drive inside the zone.  Lorries, vans or specialist heavy vehicles (over 3.5 tonnes) and buses, minibuses and coaches (over 5 tonnes) do not need to pay the ULEZ charge. Instead, they will need to pay the London Low Emission Zone (LEZ) charge if they do not meet the LEZ emissions standard.

However, with CAZ, which vehicles need to pay the charges will depend on each city and how they group vehicles by emissions. As a general rule, the higher the vehicle tailpipe emissions, the higher the charge. 

The way the rules are enforced reveals another difference between ULEZ and CAZ. Payments for ULEZ charges are via the Transport for London website, whereas CAZ charges are set by the local authorities and made via the government website. Failure to pay either, results in a Penalty Charge Notice (PCN).

How ULEZ and CAZ Work

Both initiatives are in place with the aim of encouraging drivers to choose to drive compliant vehicles. Both electric and hybrid cars tend to be exempt from emission charges based on their low emissions. The initiatives encourage drivers towards driving an electric car or avoiding zones where they are trying to establish cleaner air.  

Clean Air Zones (CAZ) are becoming more and more common in cities across the UK. They work in the same ways as the ULEZ but have instead been brought in by local authorities to improve air quality. Charges are set by local authorities and it can be worth checking your local authority to see what their rules are on non-compliant vehicles. 

Both schemes operate via cameras which read vehicle number plates driven through the zone. The data is checked against databases to see if the vehicles recorded meet emissions standards. Signs are placed to warn vehicles when they are about to enter a CAZ or a ULEZ zone. Drivers have a set amount of time to pay the charges after which they are issued with fines.

For a CAZ charge the period runs from midnight to midnight.You must pay the charge by 11:59pm on the sixth day after driving into the zone. You can pay up to 6 days before you travel. If you do not pay the charge in this time, you may get a penalty charge notice (PCN).

For a ULEZ charge, you can pay by midnight on the third day following the journey or up to 90 days in advance. 

How Areas Are Chosen

Many cities struggle to meet air quality standards and low emission zones are designed to enforce stricter controls on polluting vehicles to bring air quality within safer limits.

The implementation of low emission zones starts with defining the specific geographic areas where the restrictions should apply. Traffic data, air pollution levels, and urban layout all inform the selection of zones which are mapped to optimise the impact on air quality while minimising disruption to the transport network as much as possible.

Compliance Requirements

For ULEZ, a vehicle must meet the following criteria:

• Euro 3 for motorcycles, mopeds, motorised tricycles and quadricycles (L category).
• Euro 4 (NOx) for petrol cars, vans, minibuses and other specialist vehicles.
• Euro 6 (NOx and PM) for diesel cars, vans and minibuses and other specialist vehicles.

Lorries, vans and specialist heavy vehicles (all over 3.5 tonnes Gross Vehicle Weight (GVW)) and buses, minibuses and coaches (all over 5 tonnes GVW) do not need to pay the ULEZ charge. They will need to pay the LEZ charge if they do not meet the LEZ emissions standards.

The ULEZ is enforced based on the declared emissions of the vehicle rather than the age. However:

• Petrol cars that meet the ULEZ standards are generally those first registered as new with the DVLA after 2005, although cars that meet the standards have been available since 2001.
• Diesel cars that meet the standards are generally those first registered with the DVLA as new after September 2015.

Exemptions include certain vehicles such as taxis, historic vehicles and vehicles with a 'disabled' or 'disabled passenger vehicles' tax class. These do not currently need to pay the ULEZ charge. A number of those vehicles are automatically exempt; others must be registered with Transport for London (TfL) in order to qualify for a 100 per cent discount.

 For CAZ, a vehicle must meet the following criteria:

• Euro VI for buses, coaches and heavy goods vehicles.
• Euro 6 (diesel) and Euro 4 (petrol) for vans, minibuses, taxis, private hire vehicles and cars.
• Euro 3 for motorcycles.

You’re automatically entitled to a national exemption, and do not have to pay a charge, if you have a vehicle that’s ultra low emission, a disabled passenger tax class vehicle, a disabled tax class vehicle, a military vehicle, a historic vehicle, a vehicle retrofitted with technology accredited by the Clean Vehicle Retrofit Accreditation Scheme (CVRAS) or certain types of  agricultural vehicles.

Impact on Drivers

Who is Affected?

Drivers of the highest polluting vehicles are most likely to be affected by the charges; any vehicle which exceeds emission standards will be affected by the regulations. A fair portion will be commercial vehicles, but other types of drivers and vehicles will also not meet the standards, particularly owners of older vehicles.

Within a CAZ zone, larger vehicles such as lorries, coaches and buses that fall foul of emissions requirements are charged around £100, although the exact figure varies between cities.

Private hire cars, taxis and regular passenger vehicles that aren't compliant pay less but still incur a charge of roughly £10 a day, again varying from city to city.

Exact charges to pass through a CAZ zone vary between local authorities and different Clean Air Zones will decide which groups of vehicles they charge to enter the zone.

For example, you may not need to pay a daily charge to drive in Bath's Clean Air Zone if your vehicle does not meet emission standards, since charges do not apply to cars or motorbikes unless it is a taxi or private hire vehicle, in Bath specifically.

If a vehicle which fails to meet the emission standards is caught on camera driving in the Clean Air Zone, and does not make payment by 11:59pm on the sixth day after the date the vehicle was used in the zone, a Penalty Charge Notice (PCN) will be sent to the registered keeper of the vehicle.

The standard penalty charge is £120 and you have up to 28 days to pay the standard charge from the date of issue of the PCN, reduced to £60 if paid within two weeks.

Preparing for ULEZ and CAZ

Upgrading Your Vehicle

There are a couple of key options when it comes to ensuring your vehicle meets emission standards. You can alter your existing vehicle or upgrade to a new one:

1. Altering your existing vehicle - a retrofit means altering a vehicle’s engine to reduce its emissions. Whilst all diesel vehicles are potentially suitable for retrofit, there are some limiting factors that make some vehicles more suitable than others including space, payload and cost. The work must be accredited by the Clean Vehicle Retrofit Accreditation Scheme (CVRAS) in order for the vehicle to be deemed exempt from clean air charges.

2. Upgrade to an electric vehicle - leasing an electric vehicle can be a great way to benefit from an electric vehicle without the price tag.  

Alternative Transportation Options

There are several alternative transportation methods to get around paying a ULEZ or CAZ charge. These include:

Public Transport - Unless you need to bring equipment or tools on your journey, it’s easy to avoid driving into most ULEZ and CAZ zones, thanks to the fact most cities operate numerous transport options and park and ride schemes.

Cycling - Hire schemes and cycle lanes help make most cities increasingly bike-friendly places for those who would consider cycling as an alternative. 

Electric Car Leasing - Electric car leasing options can open up a range of benefits for drivers and businesses alike. Explore the range of electric car leases from Xcite.

Your ULEZ and CAZ FAQs Answered