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Cardiff Council

Clean Air Cardiff

​​​​​There is no doubt that air pollution is damaging to the human health and the environment. 

Public Health Wales have stated that poor air quality is probably the second greatest health concern after smoking and is the most significant environmental determinant of health. 

Recent work by Public Health Wales estimates that the equivalent of over 220 deaths each year among people aged 30 and over, in the Cardiff and Vale Health Board area, can be attributed to N​itrogen dioxide (NO2 ) pollution with many more citizens suffering ill health as a consequence of poor air quality.   

The Council has been undertaking a detailed study into air quality as a result of a legal requirement which has been placed on the Welsh Government, which requires the Council to take action to reduce pollution levels (NO2) to the legal limit which is set out in European legislation in the shortest possible time.​

Detailed air quality and transport modelling has taken place across the city to forecast NO2 levels and the results have identified one street where EU legal limits are likely to be breached in future years. The results have showed that only Castle Street, which runs in front of the Castle by Westgate Street to Duke Street, is likely to fail legal compliance beyond 2021 if nothing is done to reduce traffic pollution.

Although the modelled data, which is required under the EU Directive, has only indicated that Castle Street will be in breach of the required level, the Council also has a number of Air Quality Management Areas (AQMA) across the City, where pollution levels also remain a concern.​
The most recent Outline Business Case​​​​​​​​​​​​​​​​​​​​​External link opens in a new window has concluded that a package of non-charging measures is the preferred option when compared with a charging Clean Air Zone.

The main reason for this is that that the non charging measures deliver wider air quality benefits across all of Cardiff  when compared directly to the results of the charging Clean Air Zones.

Further government guidance is clear that where pollution limits can be met by non charging solutions that these should be the preferred option over any charging scheme. 

Air pollution on Castle Street is a symptom of a wider problem which extends far beyond this stretch of road. We have to improve the emissions of the fleet of vehicles using the road network, decrease the number of cars that drive through the city centre, and increase the use of sustainable travel alternatives such cycling and walking.

The proposed measures are currently concept designs at this stage and look to tackle the problem of air pollution in the city centre. An outline bid for funding has been made to the Welsh Government for the following schemes and these will be refined, following public consultation and cabinet approval as we develop the full business case:

  • Implementation of electric buses to replace the oldest and most polluting buses – costing £1.8m 
  • Introduction of a Bus Retrofitting Scheme for bus operators in Cardiff to upgrade older buses so they meet Euro VI engine emission standards – costing £1.4m 
  • Major changes to both Castle Street and Westgate Street and the city centre loop to allow for better and more efficient movement of public transport (buses) and increasing active travel capacity in the City Centre – costing £18.9m 
  • Review and implement a revised taxi policy to ensure that all applications to grant a ‘new vehicle license’ or for a ‘change of a vehicle on a current license’ are only approved for vehicles that meet the latest Euro 6 emission standards – costing £5.5m. 
  • Improvements to Active Travel and increased 20 mph areas – costing £4.5m View questions and answers on the clean air project.

View more information on the Clean Air Project​​​​​​​​​​​​​​​​​​External link opens in a new window
A Charging Clean Air Zone is a defined geographical area where owners who drive polluting vehicles have to pay a charge to drive through the area.

A requirement was given to the council that a charging Clean Air Zone had to be used as a benchmark for the business case to assess whether a charging scheme or non charging measures reduce the levels of pollution to the permitted levels in the ‘shortest time possible.’
City Centre CAZ.jpg

Two different Clean Air Zones were assessed, using the same geographical area.

Clean Air Zone 1 – Private cars that do not meet the emission standards. For petrol cars, the requirement is a minimum of a Euro 4 engine. For diesel cars a minimum of a Euro 6 engine. The proposed charge was £10 a day.

Clean Air Zone 2 – ​
Heavy Goods Vehicles (HGVs) and Light Goods Vehicles (LGVs) that do not meet the Euro VI/6 (Diesel) and Euro IV/4 (Petrol) emission standards. The proposed charge was £50 for HGVs and £10 for LGVs.

Older buses running on diesel fuel contribute significantly to air pollution in the city centre.

The proposed measures include a proposed £3.2m to replace the most polluting buses with electric buses, as well as a retrofitting scheme for other buses to be upgraded to a Euro Vi engine. Euro Vi engines reduce Nitrogen oxides (NOx); Carbon monoxide (CO); Hydrocarbons (HC) and Particulate matter (PM).

The majority of taxis* in Cardiff run on diesel fuel and​ the new proposed measures aims to reduce the emissions from these vehicles.

Changes to the licensing conditions are proposed for all applications for a new vehicle license, or for the change of vehicle on a current license.

As part of the business case, funding has been put forwards to the Welsh Government for an incentive scheme to assist the taxi trade with upgrading their vehicle. This hasn’t yet been approved and any final scheme will be subject to further consultation with the trade.

The previous policy has specific criteria for different categories of vehicles. The new policy intends to simplify the criteria as shown below.

*The term taxi includes both types of vehicles that we licence in the city: Hackney Carriages, which you can flag down in the street, and private hire vehicles, which you have to pre-book first​.

Current taxi licensing policy


 Saloon/Multi-Purpose Vehicles

Prestige vehicle

Purpose Built Hackney Carriage

Maximum age at first application

25 months

Under 10 years

Under 10 years

Maximum licensable age (unless vehicle complies with exceptional condition policy)

​​6 yea​rs

10 years

10 years

Age at which vehicle may be annually tested/12 month license issued

Under 4 years

Under 4 years

Under 10 years

Age at which vehicle is tested 6 monthly/6 month license issued

4 years

4 years

10 years

Proposed new taxi licensing policy


All licensed vehicles

Vehicle age/emission standard at first​ application

Under 5 years old and meet or exceed Euro 6 standard

Maximum licensable age (unless vehicles complies with exceptional condition policy)

10 years old

Age at which vehicle may be annually tested/12 month license issued

Under 5 years old

Age at which vehicle is tested 6 monthly/6 month license issued

Over 5 years​​ old

​To achieve the goals set out this plan, additional road space has to be given to both public transport and active travel in the city centre. By improving the infrastructure, sustainable travel will become a quicker and more attractive option.

At this stage of the process, the designs being put forward only show the concept of what we are trying to deliver. All of these projects will be subject to a competitive tender exercise, so there are no detailed designs at this stage. The images below show the council’s intentions in terms of the road design layout. Detailed consultation will take place on each project, when the detailed designs are available.

Download a map and explanation of changes to Central Square, Castle Street and Westgate Street (947kb PDF) ​​​​​​​​​​Link opens in a new window

Download a map and explanation of changes to Boulevard de Nantes and Station Terrace (232kb PDF) ​​​​​​​​​​Link opens in a new window


City Centre West (CCW)
The main aim of this scheme is to accommodate the new Transport Interchange and Central Square Development, whilst also Improving Air Quality within the City Centre Air Quality Management Area. This could be achieved by removing through-traffic from Westgate Street and installing a new highway layout that will improve and connect the current bus network with the new Interchange, Central Square, Central Station and the City Centre Enterprise Zone. In addition, the scheme could offer improved safety for pedestrians via improved pedestrian crossing facilities, 20mph speed limits and an improvement to the pedestrian environment outside of the national stadium. The scheme could also install a network of stepped cycle tracks to connect the area with the proposed cycleway on Castle Street and the Taff Trail routes.

City Centre North (CCN)
The main aim of this scheme is to bring Castle Street into Air Quality compliance by 2021 and install a primary Cycle Way along its length. The installation of the cycle lane and the reduction in highway space will allow for traffic to be reduced enough to target the air quality issue. Improved pedestrian crossings with countdown timers could also provide safety improvements for pedestrians. 


City centre East (CCE)
The main aim of this scheme is to provide a new dynamic for the bus network, whilst connecting primary Cycle Ways and improving the pedestrian environment outside of Queen Street Station.

This could be achieved through providing bus priority measure throughout the Station Terrace and Churchill Way areas that would provide new routes for buses, taking them away from the City Centre Air Quality Management Area and closer to key areas such as Queen Street Station and the shopping district. The new bus routing system is also key to allowing the Interchange to be accessed from its south entrance, and also work effectively on major event days. A primary Cycle Way could be installed to connect the east of the city centre with the City Centre Enterprise Zone, and join up all the other proposed primary Cycle Ways. Pedestrian improvements on Dumfries Place and Station Terrace could also improve safety for pedestrians and improve connections to Queen Street Station and the City Centre Enterprise Zone.

How will this be funded?

The Council is working directly with Welsh Government and our Final Plan will include a funding bid to Welsh Government to fund the measures to ensure that we can improve air quality in the City to comply with legal limits in the shortest possible time.

Have your say

Contact the Clean Air project team


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