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Is pollution affecting your asthma? Find out how to manage this common asthma trigger.

Two thirds of people with asthma tell us poor air quality makes their asthma worse, which puts them at higher risk of an asthma attack. Pollution is an asthma trigger that’s hard to avoid, which is why it’s so important to manage your asthma well. If you’re taking your preventer medicines regularly every day your airways are more likely to cope with high pollution days.

Poor indoor air quality can affect asthma too. Most of us spend a lot of our time inside so it’s important to be aware of what can make indoor air unhealthy, including cigarette smoke, cleaning products and wood-burning stoves.

There’s evidence that air pollution also plays a part in causing asthma in children and adults.

Why are people with asthma more at risk from pollution?

When pollution levels are high we all breathe in harmful substances; but if you’ve got asthma you’re much more likely to feel the effects. You might notice you’re coughing or wheezing, your chest is tight, or your nose and throat feel scratchy. Pollution is more of a risk for people with asthma because:

  • Pollutants, such as the chemicals in traffic fumes, can quickly irritate the airways and trigger asthma symptoms.
  • The tiny particles found in dust, soot, and diesel fumes are small enough to get right into the lungs, causing inflammation and making your asthma symptoms worse.
  • Pollution can make you more sensitive to your usual asthma triggers (such as house dust mites, pollen, pets, moulds and fungi).

Are some people with asthma more at risk than others?

Air pollution is a risk factor for everyone with asthma but if your asthma is well managed and you rarely have symptoms you’ll be much more able to cope with the effects.

Some people with asthma need to take extra care:

  • Children and young adults with asthma are more at risk from the effects of pollution because they have faster breathing rates, and their lungs are still developing.
  • Children living in areas with high pollution are more likely to have reduced lung function as adults.
  • Older people with asthma, particularly if they have underlying COPD or another long-term condition such as heart disease may find it harder to cope with pollution.
  • People with severe asthma or asthma that’s difficult to manage may find their symptoms get worse even on low pollution days.
  • People who are exposed to pollution on a daily basis, for example because they live or work near a busy main road.

How do you know if air pollution is triggering your asthma?

Keeping a symptom diary for you or your child and noting pollution levels can help you identify patterns. When pollution levels are high, and for up to a day afterwards, you might notice:

  • you’re more sensitive than usual to your other asthma triggers  
  • your symptoms are worse and harder to control
  • your peak flow score is lower than your usual score, a sign that your airways are reacting to a trigger, which could be pollution
  • you need to take your reliever inhaler more.

Can being exposed to pollution actually cause asthma?

  • Being exposed long-term to high concentrations of air pollution may cause asthma in both children and adults.
  • If you’re exposed to high levels of pollution when you’re pregnant, whether you have asthma yourself or not, your baby could be more likely to develop asthma. Particulates can cross through the placenta to the developing baby. 

What are the main pollutants in the air we breathe?

Today the most dangerous and widespread air pollutants are nitrogen dioxide, sulphur dioxide and particulates. These are mainly produced by factories, industrial sites, and traffic fumes. Ozone is produced when sunlight combines and chemically reacts with nitrogen dioxide, particulates and other gases produced by car, bus and lorry engines (particularly diesel vehicles), factories, chemical power plants and smoke from the burning of coal and oil.

On high pollution days a combination of these pollutants can cause smog. Smog can happen in both winter and summer, when the air is still. Air pollution is mostly invisible but smog can often be seen as it has a yellow or black tinge.

Pollution can stay in the air for days or even weeks, especially if the air is still and there’s no wind to blow it away.

What are the pollution hot spots?

Busy main roads

Levels of nitrogen dioxide and particulates are higher on busy urban roads, particularly when traffic is moving slowly. The biggest polluters are vehicles using diesel; half of all cars now run on diesel, as well as buses, vans, and taxis. Vehicles on the road also generate particulates like road dust and the tiny particles from brake and tyre wear. If you’re walking or cycling on main roads, or you’re driving with the car windows open you’ll be more at risk.


Higher concentrations of pollutants can be found close to airports. Aircraft produces a whole range of pollutants and studies suggest that people living near airports have higher rates of asthma and other respiratory conditions. Busy, congested airports where planes are taxiing and waiting for take-off are thought to produce the most pollution. But pollution is emitted into the air when the plane is cruising too, so the problem is not just localised to the area around an airport.


Large container ships, ferries and tankers give out pollution close to seaports and coastal areas. The pollutants can also be carried inland by wind.

Industrial sites

If you live or work near a building site, an industrial site or a power station you’ll be more exposed to pollution both from the dust, and the diesel-powered lorries and trucks.

Bonfires and barbecues

Smoke from any type of fire can make asthma symptoms worse, including barbecues, bonfires, and chimney smoke. Wood burning stoves or coal fires affect indoor air quality and also add to outdoor pollution. The smoke from fireworks and bonfires on Bonfire Night can add to winter smog and put your asthma at risk.

When are pollution levels likely to be higher?

  • On sunny days with no wind pollution is often worse. The sun reacts with nitrogen dioxide and ozone and creates toxic smog. Ozone gas levels are often higher in sunnier climates and on hot summer days. 
  • Dry, warm weather can also mean high pollen levels - and the combination of pollen and pollution can cause symptoms known as 'grey fever'.
  • Thunderstorms usually mean hot, still air before the storm breaks. This can make pollution worse because the pollutants are allowed to build up. 
  • On cold, still, foggy days pollution can get trapped close to the ground and build up over time causing what’s known as winter smog. 
  • During afternoons and evenings pollution is generally higher because the pollution has had a chance to build up during the day. 
  • During the morning and evening rush hours, when there are larger numbers of vehicles on the road. 
  • Atmospheric changes can sometimes bring pollutants from southern Europe into the UK, topping up local pollution levels and often resulting in smog alerts here.
  • Saharan dust is a mixture of sand and dust from the Sahara. A Saharan dust storm can happen several times a year, usually in the summer months, and the dust can be carried over to the UK on high winds causing poor air quality in the UK.

Find out more about how the weather can trigger asthma symptoms.

How to cope with high pollution days

It’s difficult to avoid air pollution, but the best way to minimise the effect it has on you is to make sure you’re looking after your asthma well all of the time. This means:

  • taking your preventer medicines every day as prescribed, so that you’re keeping down the inflammation in your airways
  • making sure you, and your child, have regular asthma reviews
  • using a written asthma action plan helps you look after your asthma by reminding you what symptoms to look out for and what action to take when you get them.

If your asthma is well-managed you’ll be more able to deal with all your asthma triggers, including pollution, and our pollution top tips will be more effective.

Does wearing a mask help?

There’s not enough evidence to say that wearing a face mask to avoid pollution will make a difference to your asthma symptoms. A face mask can make breathing feel more of an effort.

If you do want to try a mask though make sure:

  • the seal is a good fit around your face
  • it has a fine filter to catch the smaller particles
  • you change the filter often
  • you stop using it if it makes it harder to breathe
  • you continue to take your prescribed asthma medicines.

Pollution Top Tips

  • Be prepared! DEFRA produces daily and a five-day UK-wide pollution forecast, so you can check to see if your local area is likely to be affected in advance. Follow Asthma UK on Twitter and Facebook for asthma specific advice when there’s high pollution alerts.
  • Keep your reliever inhaler with you so you can quickly deal with symptoms if you get them.
  • Limit the time you spend outside on high pollution days.
  • Avoid physical activities and exercise close to main roads.
  • Keep your car windows closed, especially if you’re stuck in a jam of slow-moving traffic.
  • Go out earlier in the day when air quality tends to be better.
  • Stick to back streets if possible if you’re walking or cycling.
  • Avoid rush hour if possible.
  • Keep windows and doors closed so outdoor pollution can’t get in.
  • Stand well back from the smoke if you’re going to a barbecue, or a Bonfire Night party
  • Get advice from the environmental health department of your local authority if you’re worried about neighbours having barbecues or bonfires all the time.
  • Avoid cigarette smoke whether indoors or out.

 Last updated March 2016