15 Most Polluted Cities in the UK – [Updated List]

Air pollution remains a concern across many parts of the UK. Based on 2025 PM2.5 data, Northampton had the highest annual average among the locations in the latest ranking, followed by Ipswich and St Albans. 

According to the Gov.UK, air pollution contributes to 28,000-36,000 premature deaths annually in the UK. The World Health Organization also states that long-term exposure to PM2.5 significantly increases health risks, even at low concentrations.

So, what is the most polluted city in UK? Based on the latest annual PM2.5 data, Northampton recorded the highest average concentration at 10.7 µg/m³.

Here are the 15 locations with the highest annual PM2.5 concentrations in the dataset:

Note: This ranking uses average PM2.5 levels from 2025. Air pollution can change each year and can also vary with the season, weather and location. So, this list shows the pollution levels and may change when new data is available.

Northampton ranked first in the latest ranking, with an annual average PM2.5 concentration of 10.7 µg/m³.

The town’s location close to major roads, including the M1, and nearby industrial areas can contribute to higher levels of particulate pollution. Traffic is an important source of air pollution in many urban areas, particularly around busy roads.

At 10.7 µg/m³, Northampton’s annual average was more than twice the WHO guideline of 5 µg/m³.

Ipswich recorded an annual average PM2.5 concentration of 10.4 µg/m³, placing it second among the locations included in the ranking.

The town has a busy urban environment alongside its waterfront and surrounding countryside. Road traffic, construction and other urban activities can contribute to particulate pollution.

Although Ipswich is not one of the UK’s largest cities, its annual PM2.5 level shows why air quality can still be a concern in smaller urban areas.

St Albans also recorded an annual average PM2.5 concentration of 10.4 µg/m³.

The city has strong transport links and is located close to major urban areas and busy roads. Vehicle emissions and other urban activities can contribute to particulate pollution.

Brighton & Hove recorded an average PM2.5 concentration of 10.0 µg/m³.

The popular coastal location may benefit from sea breezes, but this does not prevent pollution from building up in busy areas. Traffic, construction and high levels of activity can all affect local air quality.

London is one of the UK’s largest and busiest urban areas, so it is not surprising that it continues to face air quality challenges.

Road traffic is one of the major sources of pollution in London. Construction, commercial activity and other urban sources can also contribute to airborne particles.

Liverpool recorded an annual average PM2.5 concentration of 9.8 µg/m³.

The city’s busy roads, industrial activity and port-related activity can contribute to air pollution. Areas with high traffic volumes can experience greater exposure to pollutants, particularly close to roads.

Manchester has a long industrial history and remains an important centre for business, transport and construction.

The city recorded an annual average PM2.5 concentration of 9.7 µg/m³.

Road traffic is an important source of air pollution, while construction and other urban activities can add dust and particles to the air.

Manchester’s position in the ranking shows that air pollution remains a concern across some of the UK’s largest cities.

Bournemouth recorded an annual average PM2.5 concentration of 9.6 µg/m³.

As a popular coastal destination, Bournemouth has large numbers of visitors and busy roads, particularly during peak periods. Traffic, construction and other urban activities can contribute to local pollution.

Coastal winds can help disperse pollutants, but they do not completely remove pollution from busy urban areas.

Doncaster recorded an annual average PM2.5 concentration of 9.4 µg/m³.

The area has an important transport and industrial history, with road traffic and industrial activity contributing to local air quality concerns.

PM2.5 levels can also change considerably throughout the year. Seasonal weather conditions can influence how easily pollutants disperse.

Winchester recorded an annual average PM2.5 concentration of 9.4 µg/m³.

Traffic is an important consideration for air quality in urban areas such as Winchester. Busy roads can create local pollution hotspots, particularly where traffic is slow or congested.

Luton recorded an annual average PM2.5 concentration of 9.3 µg/m³.

Road traffic, urban activity and its strong transport connections can contribute to local air pollution. Busy roads can increase exposure to vehicle emissions, especially in areas with high traffic volumes.

Nottingham recorded an average PM2.5 concentration of 9.3 µg/m³.

The city has a large population and busy transport network. Traffic and urban activity can contribute to higher levels of particulate pollution, particularly around busy roads.

Air pollution can also vary significantly throughout the year, depending on weather conditions and other local factors.

Rotherham recorded an annual average PM2.5 concentration of 9.3 µg/m³.

The area has a strong industrial history, and industrial activity, road traffic and other urban sources can affect local air quality.

Worcester recorded an annual average PM2.5 concentration of 9.2 µg/m³.

Road traffic and urban activity can contribute to pollution, while weather conditions can affect how pollutants move through the area.

Cardiff is the capital of Wales and one of its largest urban areas. It recorded an annual average PM2.5 concentration of 9.1 µg/m³.

Traffic, construction and other urban activities can contribute to particulate pollution. Busy roads can create local pollution hotspots where people may experience higher exposure.

The worst air pollution in UK urban areas usually comes from a combination of different sources. 

These can vary between cities, but some common causes include:

People spend much of their day indoors, whether at home, work, school or other buildings. This makes indoor air quality an important part of reducing exposure to airborne pollutants.

In cities with higher outdoor pollution, businesses can improve indoor air quality by using effective ventilation, filtration and regular air quality monitoring. However, outdoor pollutants can still enter buildings through doors, windows and ventilation systems.

Rensair air purification systems can provide an additional layer of protection by continuously filtering airborne particles from indoor air. 

We offer commercial air purification solutions designed for offices, healthcare facilities, schools, care homes and other busy indoor spaces. The systems can be used alongside ventilation and other indoor air quality measures to help create cleaner, healthier indoor environments.

The latest data shows that air pollution is not limited to the UK’s biggest cities. Northampton, Ipswich, St Albans and Brighton & Hove recorded some of the highest annual PM2.5 concentrations in the latest ranking, while London, Liverpool and Manchester also remained among the higher-ranking locations.

So, what is the dirtiest city in UK? Based on this PM2.5 dataset, Northampton recorded the highest annual average. However, air pollution can change by year, season, weather and location, so there is no permanent dirtiest place in UK.

While outdoor pollution requires long-term action, businesses can also take steps to improve the air inside their buildings. Effective ventilation, filtration, monitoring and air purification can all support better indoor air quality.