Air quality in Wales

Air quality index (AQI) and PM2.5 air pollution in Wales

Last update at (local time)


Real-time Wales
Most polluted city ranking

#cityUS AQI
1 Cwmbran


2 Fochriw


3 Bridgend


4 Chepstow


5 Caerphilly


6 Chirk


7 Wrexham


8 Port Talbot


9 Templeton


10 Rhyl


(local time)


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Real-time Wales
Cleanest city ranking

#cityUS AQI
1 Taibach


2 Cardiff


3 Rhyl


4 Port Talbot


5 Templeton


6 Wrexham


7 Chirk


8 Caerphilly


9 Bridgend


10 Chepstow


(local time)


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How bad is air pollution in Wales?

Wales experiences some of the United Kingdom’s poorest air quality, and air pollution presents the nation-state’s biggest environmental risk to public health. The health impacts of air pollution exposure within the country are estimated to contribute 1,400 premature deaths per year.1 The main pollutants of concern in Wales are particulate matter (PM2.5 or PM10) and nitrogen dioxide (NO2), both of which can cause a range of health impacts. Short term health effects can include irritation of eyes, nose and throat, aggravation of existing respiratory diseases such as asthma, headaches, and nausea. Long term exposure furthermore increases risk of cardiovascular and respiratory disease, and cancer.1

Wales measures its legal compliance with air quality regulations across four zones, three of which recorded illegally high levels of nitrogen dioxide (NO2) pollution during 2020, according to UK and European Union regulation. The South Wales area was listed as the 2nd worst zone across the entire UK for NO2 levels according to UK government data in 2020, second only to the Greater London Urban Area.2 The South Wales zone had a modelled maximum annual mean NO2 concentration of 64 μg/m3 (contrasted with London’s 77 μg/m3), exceeding the UK and EU legal limit for NO2 pollution (40 μg/m3) by 160%, while the North Wales zone and Cardiff Urban Area also exceeded the national legal limit (with 44 and 42 μg/m3 respectively). Only the Swansea Urban Area within Wales narrowly achieved the legal limit, with the highest permittable legal annual average of 40 μg/m3.2

Meanwhile, several locations within Wales also exceed the World Health Organisation (WHO)’s recommended guideline limit of PM2.5 pollution, of an annual average concentration below 10 μg/m3. According to IQAir’s 2019 World Air Quality Report, 4 out of 10 Welsh locations with available data exceeded this limit. The most polluted location for PM2.5 in 2019 was the town of Chepstow, with an annual average of 12.6 μg/m3; followed by major cities Cardiff (11.5 μg/m3), Swansea (11.2 μg/m3) and the town of Port Talbot (10.3 μg/m3).3 While Chepstow has a smaller population than the cities of Cardiff and Swansea, its growing number of residents and associated traffic is one reason credited as contributing to the town’s air pollution problems.4 Additionally, traffic congestion along the main artery road through the town, serving commuters along the A48 and A466 combined with an out-of-date road network are highlighted as additional contributing factors to the high levels of harmful local PM2.5.4

Real-time air pollution levels and Wales air quality forecast can be viewed within the Wales air quality map at the top of this page, and also accessed using the IQAir AirVisual air pollution app.

What are the main sources of air pollution in Wales?

The main source of Wales particulate matter (PM) pollution is domestic solid fuel burning, while other contributing sources include industrial processes, vehicle exhaust and braking, as well as natural sources such as wind-blown dust, pollen, soil particles and sea salt.1

Wales’ nitrogen dioxide (NO2) pollution is generated through industrial processes involving combustion, power generation, and through road transport emissions. Road transport is the biggest contributor to NO2 air pollution in Wales, contributing approximately one third of emissions. Accordingly, NO2 concentrations are often found to be particularly high at roadsides.1

What is being done about air pollution in Wales?

Unlike Scotland, which has developed its own independent Scotland Air Quality Strategy and lower air pollution limits than the EU, air quality regulation in the nation-state Wales is mostly determined by EU and UK-wide regulations. In accordance with the UK and EU regulations, Wales’ annual target limit for PM2.5 is 25 μg/m3, and annual limit for NO2 pollution is 40 μg/m3 on average, with a further limit that no single location should exceed a measure of 200 μg/m3 of NO2 more than 18 times per year.5

Like most of the UK, Wales air quality management is primarily carried out by local authorities. In accordance with EU air quality directives, the Welsh government monitors country-wide air quality levels across 4 main zones, with local authorities responsible to meet the national objectives within each zone: North Wales, South Wales, and the agglomerations of Cardiff Urban Area and Swansea Urban Area.6 Also in accordance with the rest of the UK, Wales adopts the UK government’s Daily Wales Air Quality Index (DAQI), which converts pollution concentrations into a scale of 1 to 10, with 1 indicating “Low” health hazard, and 10 indicating “Very High” health hazard.7 The Daily Wales AQI scale is a method of communicating a range of pollutant information (which may include PM2.5, PM10, NO2, sulphur dioxide (SO2), and ozone (O3)), via a single indicator of overall health risk.7

In August 2020, the Welsh government issued a new Clean Air Plan for Wales, which includes several new air quality management initiatives and targets across the country. These include:

  • Investing in active travel infrastructure, and targeting a zero tailpipe exhaust emission taxi and bus fleet by 2028
  • Investigating the implementation of Clean Air Zones and/or Low Emission Zones
  • Implementing an Electric Vehicle Charging strategy, to incentivize the uptake of lower-carbon transport
  • Increasing local air quality monitoring by developing a new Air Pollution Monitoring Network, with a focus on vulnerable members of the population.1

Where in Wales has the best air quality?

Six out of ten locations with available data in Wales achieved the WHO’s annual average target for PM2.5 pollution during 2019, with an annual average PM2.5 concentration below 10 μg/m3.3 The locations with the cleanest PM2.5 air quality were jointly Llanfairpwllgwyngyll and Brynteg, both with 6.1 μg/m3; followed by Narberth (6.4 μg/m3), Llynfaes (7.3 μg/m3), Wrexham (8.0 μg/m3), and Newport (9.7 μg/m3).3

For NO2 pollution, Swansea air quality within its Urban Area agglomeration was found to have the lowest levels of any air quality zone within Wales during 2020.2

How polluted is Cardiff?

In IQAir’s 2019 World Air Quality Report, Cardiff ranked as the UK’s twentieth most polluted city for PM2.5 levels, and the 2nd most polluted city in Wales, with an annual average concentration of 11.5 μg/m3. This exceeds the WHO’s recommended annual guideline of 10 μg/m3, and ranks the Welsh capital as slightly more polluted than London, which averaged 11.4 μg/m3. However, Cardiff air pollution ranked second to the town of Chepstow within Wales, exceeding Cardiff’s annual average PM2.5 with a higher average of 12.6 μg/m3.3

Cardiff Urban Area’s NO2 pollution was shown to exceed the UK and EU annual legal limit of 40 μg/m3 during 2020, with a maximum modelled annual mean concentration of 42 μg/m3.2

What is Wales’ most polluted road?

During 2015 and 2016, the roads of Woodside Terrace and Hafodyrynys Road in Crumlin, near the cities of Newport and Cardiff, were recorded as having the highest levels of NO2 pollution outside London, regularly breaching the UK and EU legal annual NO2 limit of 40 μg/m3. The road is one of the only routes connecting the Ebbw and Afod Lwyd valleys aside from the M4, and consequently it experiences heavy traffic of all types.8 Particular concerns for Woodside Terrace have arisen regarding the terraced homes that line this road, and the hazards of both the fast-moving traffic which make the road difficult to cross, as well as the unsafe levels of NO2 pollution that residents are exposed to.9 As a result of these concerns, eventually in 2020 £6 million (approximately $7.8 million USD) was awarded to demolish 23 affected homes along the A472, with part of the money allocated to “buy” the properties from their residents at above their market value, enabling them to purchase new properties elsewhere to escape the hazardous air pollution.9 The demolition project is due to be completed in December 2021.10

+ Article Resources

[1] Llywodraeth Cymru, Welsh Government. “The Clean Air Plan for Wales: Healthy Air, Healthy Wales”. Welsh government website, August, 2020.
[2] Client Earth. “UK Air Pollution: How Clean Is the Air You Breathe?”. ClientEarth website, October 8, 2020.
[3] IQAir. “2019 World Air Quality Report”. IQAir website, March 18, 2020.
[4] Marcus Hughes. “The Welsh town left gridlocked by rising population, an out-of-date road network and the scrapping of the Severn tolls”. Wales Online, May 26, 2019.
[5] UK Government Department for Environment, Food and Rural Affairs (DEFRA). “National air quality objectives and European Directive limit and target values for the protection of human health”. UK Government website, n.d.
[6] Llywodraeth Cymru, Welsh Government. “Tackling roadside nitrogen dioxide concentrations in Wales”. Welsh government website, November, 2018.
[7] UK Government DEFRA. “What is the Daily Air Quality Index?”. UK Government website, n.d.
[8] Marcus Hughes. “Wales' most polluted street - where residents wish their homes would be torn down”. Wales Online, June 4, 2019.
[9] ITV. “Homes on one of UK's 'most polluted' streets to be demolished for £6m”. ITV website, July 29, 2020.

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