The roll-out of ultra low emission zones (ULEZs), clean air zones (CAZs) and other pollution-reducing schemes in cities across the UK is accelerating in 2023 and beyond.
Following the implementation of the UK’s first ULEZ in London in April 2019 and its subsequent expansion scheduled for 29 August 2023, similar initiatives have been established in other major cities across England and Scotland, from Birmingham and Oxford to Glasgow and Aberdeen.
What are clean air zones and how do they work?
The basic premise of CAZs is similar to that of congestion zones. An area is marked out within a city, usually focused on the city centre. Vehicles travelling within this zone and judged to be excessively polluting face charges, depending on the size of the vehicle.
Larger vehicles like lorries, coaches and buses that don't meet emissions requirements (explained in more detail below) are charged around £100, although this varies between cities. Private hire cars, taxis and regular passenger vehicles that aren't compliant can expect to pay less but still incur a charge of around £10 a day.
Like London’s already existing ULEZ, the CAZs will be distinguished by signs to make motorists aware that they're entering the zone. They will also be ringfenced by numberplate-recognition cameras. These make a note of every vehicle that passes through the zone and checks them against a database to determine the charge.
The CAZs will, mostly, be in effect 24 hours a day, seven days a week. No reprieve is granted for bank holidays.
Which vehicles will be affected?
Since the goal of CAZs is to reduce emissions and improve air quality, zero-emissions vehicles have nothing to fear. However, drivers of vehicles that do emit pollutants may be liable for charges. Two factors determine whether you will face a charge and at what level: how many emissions your vehicle produces and what type is it, since, depending on the CAZ class, certain types of vehicles are exempt.
The general rule is that to travel within a CAZ without a charge, your vehicle has to be at least a Euro 4 emission standard compliant petrol model - in other words, registered after January 2006 - or, if it is a diesel, compliant with Euro 6 standards (registered after September 2015). If your vehicle meets these standards, in all probability you will not have to pay a charge.
However, even if your vehicle does fall outside of Euro 4 or 6, you may still be able to avoid a charge, depending on what kind of vehicle it is and the type of CAZ that you wish to drive through. Four types of CAZ exist, each of which targets different classes of vehicles. These are:
Class A, which targets buses, coaches, taxis and private hire vehicles (PHVs).
Class B, which targets buses, coaches, taxis, PHVs and heavy goods vehicles (HGVs),
Class C, which targets buses, coaches, taxis, PHVs, HGVs and light goods vehicles (LGVs),
Class D, which targets buses, coaches, taxis, PHVs, HGVs LGVs and cars.
Most of the CAZs that are scheduled to be introduced in the UK are Class D. But cities such as Bath and Portsmouth will be Class C only, so in these cities, regular passenger vehicle drivers will not have to pay.
Finally, it's important to note that nearly all CAZs make special exemptions for residents within the zone, Blue Badge holders and vehicles with a disabled tax class, although the scale of the exemption offered varies between cities.
Which cities are introducing CAZs?
Somewhat unsurprisingly, an increasing number of towns are planning introductions of their own clean air zones. These include
Basildon clean air zone: Opposed by local councils, this could see restrictions imposed on the A127 arterial route.
Caerphilly clean air zone: A total HGV ban is under consideration, with a clean air zone on the A472 at at Hafodrynys Hill.
Cambridge clean air zone: A clean air zone within the current Air Quality Management Area is under consideration. This could include the historic centre as well as the inner ring road.
Canterbury clean air zone: Canterbury is planning other measures to combat emissions. These include anti-idling measures and incentives for taxi and bus companies to switch to low-emission vehicles.
Cardiff clean air zone: Cardiff favours the introduction of a £2-per-day congestion charge for non-residents over a CAZ.
Coventry clean air zone: Rather than a clean air zone, the government has accepted Coventry's targeted road improvement schemes and planned introduction of a number of cycle lanes.
Derby clean air zone: Like Coventry, Derby is proposing a range of road improvements and cycle schemes. Derby opposes the introduction of a CAZ.
Exeter clean air zone: Opposed by the city council, Exeter favours measures to increase the use of public transport over restricting access to certain vehicles.
Leeds clean air zone: Leeds no longer requires a CAZ due to a shift to low-emission vehicles. It found that more than 80% of buses and HGVs were powered by Euro 6 engines, and therefore would be exempt anyway.
Leicester clean air zone: Like Leeds, Leicester no longer requires a CAZ following air quality improvements.
Liverpool clean air zone: No details of Liverpool's CAZ have been announced, but a blanket diesel ban has been mooted. This is in addition to anti-idling plans.
Manchester clean air zone: Currently under review, Manchester's clean air zone is expected to run 24 hours a day, seven days a week, but private cars will be exempt.
Nottingham clean air zone: The city of Nottingham doesn't require a CAZ following plans to reduce emissions from buses, taxis and the council fleet.
Southampton clean air zone: A non-charging CAZ has been running since 2017, and there a no plans to make it chargeable following a raft of measures concerning taxis, buses, HGVs and emissions are the port.
Sefton clean air zone: The Merseyside town has commissioned a CAZ report, but plans are undecided.
St Albans clean air zone: A CAZ is under consideration, but is expected to major on anti-idling measures, rather than a chargable clean air zone.
Warrington clean air zone: The council has adopted a five-year pollution reduction plan, but a CAZ remains under consideration.
Wokingham clean air zone: Emission reductions are targeted in two areas following an air quality plan. A low-emission zone is being considered.
Which cities have clean air zones?
Aberdeen clean air zone
Live since: May 30 2022 but will be enforced from May 2024
Zone type: Class C
Cost per day for HGVs, buses and coaches: £60
Cost per day for taxis: Unknown
Cost per day for regular passenger cars: £60
Aberdeen was the second Scottish city to gain a clean air zone, which came into place from May 2022. A major chunk of the city centre is covered by the zone, but the city council’s research suggests that some areas of pollution will remain even with a LEZ zone in place, unless further traffic reduction measures are introduced. The council will seek to implement changes to roads in the city centre to prioritise people walking, wheeling, cycling and using public transport. Blue badge holders are exempt from this charge, as with all other Scottish cities.
Bath clean air zone
Live since: 15 March 2021
Zone type: Class C
Cost per day for HGVs, buses and coaches: £100
Cost per day for taxis: £9
Cost per day for regular passenger cars: £0