What is a LEZ, ULEZ, or CAZ?

Your Guide to Low Emission Zones and Clean Air Zones in the UK.

What is a LEZ, ULEZ, or CAZ?

Low Emission Zone (LEZ)

A Low Emission Zone is an area where specific regulations are in place to limit emissions from vehicles, particularly targeting older, more polluting vehicles. Access to these zones may be restricted or subject to charges for vehicles that do not meet the required emission standards.

Ultra Low Emission Zone (ULEZ)

An Ultra Low Emission Zone is an even stricter version of a LEZ. It typically imposes stringent emission standards, often requiring vehicles to meet specific criteria for their emissions to enter the zone. Vehicles that do not meet these standards may be subject to charges.

Clean Air Zone (CAZ)

A Clean Air Zone is a designated area where measures are taken to improve air quality. This can include penalty schemes for vehicles that don't meet emission standards or encouraging the use of low-emission vehicles through incentives.

Why Do They Exist?

The Ultra Low Emission Zone (ULEZ) sign on Uxbridge Road in London.

Low Emission Zones, Ultra Low Emission Zones, and Clean Air Zones are primarily established to combat air pollution and improve overall air quality in urban areas. The reasons behind their creation include:

Health Concerns

Poor air quality, primarily caused by emissions from vehicles, can have detrimental effects on public health, leading to respiratory problems and other illnesses. Air pollution contributes to over 28,000 premature deaths in the UK every year. These zones aim to reduce the health risks associated with air pollution. They can also help encourage more active modes of travel within the zones.

Environmental Sustainability

Implementing these zones is a step towards achieving sustainability goals by decreasing greenhouse gas emissions and promoting cleaner transport options.

Legal Obligations

The UK government has legal obligations to meet air quality standards set by both national and international regulations. Creating these zones is a way to meet these standards and avoid potential fines for non-compliance.

Notable Examples of LEZ, ULEZ, and CAZ:

London ULEZ: London's Ultra Low Emission Zone is one of the most well-known in the UK. The ULEZ zone was recently expanded on August 29th 2023 and operates across all London boroughs and the City of London. The M25 is not in the zone. Vehicles that do not meet these standards must pay a ULEZ charge to drive within the zone.

Birmingham CAZ: Birmingham introduced a Clean Air Zone in June 2021, aimed at reducing nitrogen dioxide levels. It imposes charges on older, more polluting vehicles driving within the city center. The CAZ encourages the use of cleaner transportation options.

Glasgow LEZ: Glasgow’s Low Emission Zone, came into force in June 2023, focusing on improving air quality and encouraging the use of cleaner vehicles. The zone aims to enhance the city's environmental and health standards.


Low Emission Zones, Ultra Low Emission Zones, and Clean Air Zones are playing a pivotal role in crucial for UK drivers who are either transitioning to electric vehicles or seeking to reduce their environmental footprint. These zones play a vital role in tackling air pollution, enhancing public health, and advancing environmental sustainability. As more cities across the UK adopt similar measures, staying informed and adapting to cleaner transportation options will become increasingly important for all drivers.

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