- October 3, 2026
Air quality can make a noticeable difference to people living with asthma, particularly in busy urban areas where traffic, construction, heating and other sources contribute to pollution. While not every city has the same pollution profile, exposure to pollutants such as nitrogen dioxide (NO₂), fine particulate matter (PM2.5), PM10 and ozone can aggravate respiratory symptoms and make asthma harder to control.
The latest UK air-quality assessment shows that air pollution remains a health concern even though national air quality has improved in many respects. In the 2024 assessment, Defra reported supplementary-assessment NO₂ exceedances in several major urban areas, including the West Midlands, Greater Manchester, Liverpool and Bristol. At the same time, all assessed UK zones met the relevant annual mean PM2.5 limit value used in the assessment.
For people with asthma, however, meeting a legal or regulatory limit does not necessarily mean that every location is equally comfortable or risk-free. Short-term increases in pollution can still worsen symptoms, especially in people who are more sensitive to air pollution.
This guide explains which UK cities and urban areas deserve particular attention, how air pollution affects asthma, where exposure can be highest and what people with asthma can do to reduce their exposure.
Air pollution refers to harmful substances or particles in the air. In cities, common pollutants include nitrogen dioxide, particulate matter and ozone.
The NHS identifies high levels of air pollution as one of the triggers that can worsen asthma symptoms. Common asthma symptoms include wheezing, coughing, shortness of breath and a tight feeling in the chest.
Air pollution can irritate the airways and contribute to inflammation. For someone with asthma, this may mean:
More coughing or wheezing
Increased chest tightness
Shortness of breath
More frequent asthma symptoms
Greater difficulty exercising outdoors
Increased need for a reliever inhaler
A higher risk of symptoms during pollution episodes
Government health advice also states that short-term exposure to air pollution can worsen asthma symptoms, with effects potentially appearing within hours or over several days.
If you already have an asthma action plan, it is important to continue following it rather than changing medication simply because pollution levels are elevated. For more information, see our guide to an Asthma Action Plan.
Not all pollution is the same. Different pollutants affect the respiratory system in different ways.
NO₂ is strongly associated with road traffic and combustion. It is particularly relevant in areas with heavy traffic, busy junctions, major roads and congestion.
Defra’s 2024 assessment reported supplementary-assessment annual mean NO₂ exceedances in the West Midlands, Greater Manchester, Liverpool and Bristol urban areas.
This does not mean that every neighbourhood within those regions has poor air quality. Pollution can vary considerably between individual roads and locations.
PM2.5 refers to very small particles measuring 2.5 micrometres or less in diameter. Because these particles are so small, they can penetrate deeply into the respiratory system.
Sources can include:
Road traffic
Combustion
Domestic heating
Industrial activity
Construction
Agricultural sources
Secondary particles formed in the atmosphere
Defra reported that all assessed UK zones met the relevant 20 µg/m³ annual mean PM2.5 limit value in its 2024 compliance assessment. However, this should not be interpreted as meaning that PM2.5 has no health impact. The government continues to treat particulate pollution as an important public-health issue.
PM10 consists of particles with a diameter of 10 micrometres or less. Road dust, construction activity and other sources can contribute to PM10 levels.
Ground-level ozone can increase during certain weather conditions and pollution episodes. It can irritate the airways and worsen respiratory symptoms.
The UK Health Security Agency notes that air pollutants including ozone, nitrogen dioxide and sulphur dioxide can exacerbate respiratory conditions.
There is no single official ranking of “the worst UK cities for asthma.” Air quality changes by pollutant, season, weather, traffic conditions and exact location.
A better approach is to identify urban areas where official monitoring and assessment have found particular air-quality concerns.
The West Midlands urban area is one of the major regions that deserves attention when discussing traffic-related air pollution.
Defra’s 2024 assessment recorded an annual mean NO₂ exceedance for the West Midlands Urban Area through supplementary assessment.
Birmingham has extensive road networks, busy commuter routes and areas of concentrated traffic. This means pollution can vary significantly from one part of the city to another.
People with asthma may therefore want to pay particular attention to air-quality information when travelling through heavily trafficked areas or exercising outdoors near busy roads.
Greater Manchester was also recorded as having an annual mean NO₂ exceedance through supplementary assessment in the 2024 Defra assessment.
The region includes a large urban population and extensive transport networks. Traffic-related pollution can be particularly relevant around major roads and congested areas.
For people with asthma, the issue is not necessarily that the entire Greater Manchester region has poor air quality at all times. Instead, exposure can be more concentrated around certain locations and during particular periods.
Liverpool Urban Area was another area where Defra reported an annual mean NO₂ exceedance through supplementary assessment for 2024.
Busy roads and urban traffic can contribute to localised pollution. People who spend a lot of time close to major roads may therefore have greater exposure than someone living or working in a quieter, less trafficked area.
Bristol also appeared among the urban areas with an annual mean NO₂ exceedance through supplementary assessment in the 2024 assessment.
The city has a combination of dense urban development, road traffic and commuter movement, making local traffic-related air pollution an important consideration.
London deserves special attention because of its size, population density and traffic levels.
However, it would be misleading to describe the entire capital as having the same air quality. Pollution can differ substantially between boroughs, roads and neighbourhoods.
Defra’s 2024 assessment recorded the Greater London Urban Area as compliant with the relevant annual mean NO₂ limit value. At the same time, Defra’s AQMA data shows numerous local Air Quality Management Areas in London, including areas where NO₂ and/or PM10 have been identified as pollutants of concern.
For people with asthma, the practical lesson is that living in London does not automatically mean having poor air quality, but living or spending significant time beside busy roads can increase exposure.
Other UK cities and urban areas also have local air-quality management measures or monitoring locations.
Defra’s AQMA database includes areas across England, Wales, Scotland and Northern Ireland. Current AQMA records include locations associated with pollutants such as NO₂ and PM10.
This is why a national city ranking can be misleading. A busy road in a city with generally good background air quality may expose someone to higher pollution than a quieter residential area in a larger city.
Living close to heavy traffic can increase exposure to traffic-related pollutants, particularly nitrogen dioxide and particulate matter.
UK government guidance notes that air pollution can exacerbate asthma and that there is evidence connecting exposure to air pollution with respiratory effects. It also highlights the importance of reducing exposure for people with respiratory conditions.
The effect is particularly relevant for:
Children
Older adults
People with existing asthma
People with other lung conditions
People who exercise outdoors near major roads
People who live or work close to heavily trafficked routes
However, proximity to a road is only one factor. Weather, building ventilation, traffic volume, road layout and the type of pollution all influence actual exposure.
It is tempting to ask which city is “worst,” but asthma risk cannot be calculated from a city name alone.
A person with asthma living beside a heavily trafficked road may have very different exposure from someone living several miles away in a quieter area of the same city.
The 2024 Defra assessment provides useful evidence about regional air quality, but it should not be interpreted as an asthma league table. For example, Greater London was compliant with the relevant annual mean NO₂ limit at the urban-zone level, while the West Midlands, Greater Manchester, Liverpool and Bristol had supplementary-assessment NO₂ exceedances.
In other words:
City-level air-quality data is useful for understanding broad patterns, but local pollution exposure matters more when considering an individual’s asthma.
Road traffic is a major source of urban air pollution.
Exhaust emissions and traffic-related particles can contribute to exposure to NO₂ and particulate matter. Pollution may be particularly noticeable around:
Major roads
Busy junctions
Motorways
Bus stations
Congested commuter routes
School drop-off areas
Construction zones
Car parks
Areas where vehicles frequently idle
A London NHS respiratory resource specifically advises people with asthma to avoid heavily trafficked areas, particularly at rush hour, when pollution levels are high.
This does not mean people with asthma should avoid cities completely. Small changes to routes and timing can sometimes reduce exposure without significantly changing daily routines.
Air pollution is not constant throughout the day.
Pollution levels can be affected by:
Traffic volume
Weather conditions
Wind speed
Temperature
Atmospheric mixing
Industrial activity
Domestic heating
Seasonal conditions
Long-range pollution transported from elsewhere
Rush hour can be particularly relevant in traffic-heavy areas.
However, pollution patterns vary by location. This is why checking the current air-quality forecast can be more useful than assuming that a particular city is always polluted.
The UK Daily Air Quality Index (DAQI) provides health advice according to pollution levels, ranging from low to very high.
You cannot completely eliminate outdoor air pollution, but you can reduce unnecessary exposure.
If you have asthma and plan to run, cycle or undertake strenuous exercise outside, check the air-quality forecast first.
When pollution is high, consider reducing the intensity or duration of outdoor exercise.
Government advice recommends that people with lung conditions adapt physically demanding outdoor activity when pollution levels are high, particularly if symptoms worsen.
A route through a park or quieter residential street may expose you to less traffic pollution than a route beside a major road.
This can be particularly useful for:
School journeys
Daily commuting
Walking the dog
Outdoor exercise
Cycling
If practical, travel outside the busiest periods or choose less congested routes.
This is particularly relevant for children with asthma who may spend considerable time near roads during school drop-off and collection.
Air pollution management is only one part of asthma control.
If you frequently experience symptoms, wake at night because of asthma or need your reliever inhaler more often, speak with your GP or asthma healthcare professional.
You should also make sure you understand your inhaler technique. Our guide, Is Your Inhaler Technique Wrong?, explains why correct technique matters for getting asthma medication into the lungs effectively.
An asthma action plan can help you recognise worsening symptoms and understand what to do.
If you do not already have one, read our guide to an Asthma Action Plan for more information.
Air pollution can trigger or worsen asthma symptoms and may contribute to asthma attacks in people who are sensitive to pollution.
The NHS lists high levels of air pollution among possible asthma triggers.
The UK government also advises that high and very high pollution levels can worsen symptoms in people with lung conditions.
However, asthma attacks can have multiple triggers. These can include infections, allergens, exercise, cold air, smoke and other irritants.
That means pollution should be considered as one possible trigger rather than the only explanation for worsening asthma.
If your symptoms are becoming more frequent or your medication is not controlling them effectively, speak to a healthcare professional.
If air pollution reaches a high or very high level, people with asthma should consider reducing exposure, particularly if they notice symptoms.
Useful steps include:
Check the Daily Air Quality Index.
Reduce strenuous outdoor exercise.
Avoid busy roads where practical.
Choose quieter routes when travelling.
Follow your existing asthma action plan.
Keep prescribed inhalers available.
Monitor symptoms carefully.
Seek medical advice if symptoms are worsening or treatment is not helping.
Government guidance specifically recommends that people with lung conditions adapt strenuous outdoor activity when pollution levels are high and follow their agreed management plan.
Yes.
It is easy to focus entirely on outdoor pollution when discussing asthma, but indoor air quality can also affect respiratory symptoms.
Potential indoor triggers include:
Tobacco smoke
Vaping aerosols
Dust
Mould
Damp
Cleaning sprays
Strong fragrances
Poor ventilation
Cooking fumes
The UK Health Security Agency notes that asthma symptoms can be worsened by air pollution and airborne allergens.
If you spend most of your day indoors, reducing indoor triggers may be just as important as considering outdoor pollution.
Air pollution is only one potential asthma trigger.
Depending on the individual, symptoms may also be triggered by:
Pollen
Dust mites
Mould
Animal allergens
Cold air
Exercise
Respiratory infections
Smoke
Strong smells
Certain medicines
Stress
This means someone may experience worse asthma symptoms during a particular season even if air pollution is not unusually high.
Keeping a record of symptoms and potential triggers can help you identify patterns to discuss with your healthcare professional.
Children can be particularly sensitive to environmental factors because their lungs are still developing.
UK government guidance identifies respiratory effects associated with air pollution, while NHS respiratory resources specifically highlight traffic-related pollution as a trigger for children and young people with asthma.
Parents and carers can reduce unnecessary exposure by:
Checking pollution forecasts
Avoiding busy roads during high-pollution periods
Choosing quieter walking routes
Reducing strenuous activity outdoors when pollution is high
Avoiding vehicle idling around schools
Keeping the child’s asthma action plan accessible
Ensuring prescribed inhalers are available
Schools can also play a role by reducing vehicle idling and considering traffic-related pollution around school entrances and playgrounds. NHS London asthma guidance highlights these issues as part of asthma management.
The picture is mixed.
The UK has made significant progress in reducing several forms of air pollution over the long term, but pollution remains a public-health concern.
Defra’s 2024 assessment found that the UK continued to meet the relevant PM2.5 annual mean limit used under the Air Quality Standards Regulations, while some urban areas still had NO₂ exceedances based on supplementary assessment.
The UK’s urban background PM2.5 concentration was reported as 7.2 µg/m³ in 2024, compared with 7.3 µg/m³ in 2023 and 8.3 µg/m³ in 2022.
So although national and urban-background measures show improvement in some areas, local pollution hotspots remain important.
An Air Quality Management Area, or AQMA, is an area where a local authority has identified air-quality concerns that require management action.
Defra’s current AQMA data includes hundreds of areas across the UK, with nitrogen dioxide being one of the most common pollutants for which AQMAs have been declared.
AQMAs can therefore provide another useful way of understanding local air-quality problems.
However, an AQMA should not automatically be interpreted as meaning that everyone living there has an asthma problem. It indicates that air-quality management action is required for a particular pollutant or objective.
Rather than relying solely on a list of the “worst UK cities for air pollution,” check the current conditions for the specific location where you live, work or exercise.
Useful information includes:
Daily Air Quality Index
Local authority air-quality information
UK-AIR monitoring data
Pollution forecasts
Local AQMA information
Traffic conditions
Defra operates national air-quality monitoring and assessment systems covering urban, suburban, roadside, industrial and rural locations. Its annual assessment draws on monitoring networks and modelling data.
This is particularly important because pollution can vary considerably even within the same city.
If you have asthma and notice that your symptoms are becoming more frequent, do not simply assume that pollution is responsible.
You should speak with a GP or asthma healthcare professional if:
Your symptoms are becoming more frequent
You are waking at night because of asthma
Your usual treatment is not controlling symptoms
You are using your reliever inhaler more frequently
You are struggling with normal activities
You are concerned about your breathing
The NHS recommends seeking medical advice when asthma symptoms are not adequately controlled or treatment is not helping.
If you are experiencing a severe asthma attack or severe difficulty breathing, seek urgent medical help.
There is no single city that can accurately be labelled the “worst place in the UK for asthma.” Air pollution exposure varies considerably between cities, neighbourhoods and even individual roads.
The latest Defra 2024 assessment identified supplementary-assessment annual mean NO₂ exceedances in the West Midlands, Greater Manchester, Liverpool and Bristol urban areas. London had compliance at the Greater London urban-zone level, although numerous local AQMAs remain across the capital.
For people with asthma, the most important points are:
Air pollution can worsen asthma symptoms.
Traffic-related pollution is particularly relevant in busy urban locations.
NO₂ and particulate matter are important pollutants to consider.
Pollution can vary dramatically within the same city.
High pollution days can require changes to outdoor activity.
Checking the Daily Air Quality Index can help you make informed decisions.
Following an asthma action plan remains important.
Correct inhaler technique is an essential part of asthma management.
Persistent or worsening symptoms should be discussed with a healthcare professional.
Ultimately, where you live is only one part of your exposure to air pollution. Your distance from busy roads, daily travel routes, workplace, outdoor activities, weather conditions and indoor environment can all make a difference.
For more UK health information, visit the Health Cresto Blog.
There is no official nationwide ranking of cities specifically by asthma risk. Defra’s 2024 assessment identified NO₂ exceedances in several urban areas, including the West Midlands, Greater Manchester, Liverpool and Bristol, while London has numerous local AQMAs.
London has areas with significant traffic-related air pollution, but air quality varies considerably across the capital. The Greater London Urban Area was compliant with the relevant annual mean NO₂ limit in the 2024 Defra assessment, while local AQMAs remain in many parts of London.
Yes. High levels of air pollution can trigger or worsen asthma symptoms. The NHS lists high air pollution among asthma triggers, while government guidance recommends reducing exposure when pollution levels are high.
There is no single pollutant that is universally “worst” for every person with asthma. Nitrogen dioxide, particulate matter and ozone can all contribute to respiratory irritation and worsening symptoms.
You can often continue normal activities when air pollution is low. When pollution is high, government guidance recommends that people with lung conditions adapt strenuous outdoor activity, particularly if symptoms worsen.
Check pollution forecasts, avoid heavily trafficked areas when pollution is high, choose quieter routes and make sure your child has an up-to-date asthma action plan. Reducing vehicle idling around schools can also help reduce exposure.
Moving may change your exposure to certain pollutants, but it is not guaranteed to improve asthma. Air quality varies within cities, and asthma has many potential triggers. Consider the specific neighbourhood, traffic levels and local air-quality data rather than choosing a city based solely on a general ranking.
The UK government provides air-quality information and the Daily Air Quality Index, which gives health advice according to current pollution levels.
This article is intended for general health information and should not replace personalised medical advice, diagnosis or treatment. If you have asthma and your symptoms are worsening, speak with your GP, asthma nurse or another qualified healthcare professional. In an emergency or severe breathing difficulty, seek urgent medical assistance.