Indoor asthma triggers

From gas cookers to air fresheners, if your asthma symptoms are worse at home it could be down to common indoor pollutants

Health advice > Asthma triggers

If you have asthma, you’re more at risk from poor air quality indoors, especially if you spend a lot of time at home. Many common indoor pollutants are small enough to get into the lungs and make your asthma symptoms worse.

“The best way to cope with asthma triggers, indoors or out, is to take your preventer medicines regularly as prescribed so your airways are less likely to react,” says Dr Andy Whittamore, Asthma UK’s in-house GP. “And carry your reliever with you at all times so you can deal with any symptoms quickly. If you notice symptoms getting worse, see your GP so you can review your asthma treatments.” 

Top triggers like damp and mould, dust mites, pets and cigarette smoke are covered in detail on their own pages.

On this page: 

6 top tips for indoor air pollution

  1. Open windows if you can (be cautious on high pollen or pollution days) or use extractor fans, especially in kitchens and bathrooms. It’ll help clear any indoor pollutants and prevent damp and mould.
  2. Reduce dust mites as much as possible by regularly washing bedding or using anti-allergy covers. Read more on dust mites.
  3. Avoid aerosols and sprays – go for non-spray cleaning and personal products.
  4. Avoid strong smells and chemicals – look for mild or unscented products, and products low in VOCs (Volatile Organic Chemicals).
  5. Don’t smoke. Cigarette smoke is a dangerous asthma trigger. And it can also make you and your child more sensitive to other indoor triggers.
  6. Make sure any heaters, cookers and boilers are serviced regularly. Also make sure any new appliances are fitted properly with adequate ventilation. 

Keep your home well aired

Keeping your home well aired can help to reduce exposure to some common indoor triggers. It means any fumes from fires, cookers, cleaning products, paints, aerosols and sprays are cleared away more quickly. And it helps prevent problems like damp and mould.

It also helps keep humidity down which is good news if you’re worried about dust mites which like humid conditions.

Opening windows, using fans

Opening windows and doors is important for helping indoor fumes and dust escape. Some windows have small vents built into them known as ‘trickle vents’, which you can keep open. But it can also let in outdoor triggers like pollen and air pollution.

Weather and season can affect indoor and outdoor pollution. So take care on high pollution or pollen days if these are triggers for your asthma. And remember to open windows in winter, when there are typically higher levels of pollutants in your home because of using gas appliances and fires more. 

Watch out for dusty fans or extractors or you’ll end up blowing dust all round the room.

Air filters or purifiers

Some people tell us having an air filter or air purifier helps them with their asthma symptoms triggered by dust mites or mould. But they can't remove all allergens and even a few left behind can trigger asthma symptoms.

Managing your asthma well with asthma medicines, using an asthma action plan, and seeing your GP or asthma nurse regularly will have far more benefits.

“Air filters can’t remove all allergens and even a few left behind can trigger asthma symptoms,” says Dr Andy. “And for something like second hand cigarette smoke, the best advice is always not to smoke in the first place, particularly around children.” 


De-humidifiers keep the air dry, but there isn’t much evidence about how effective they are. Or how much difference they can make to asthma symptoms.

“Some people with asthma find that de-humidifiers can leave the air too dry and make them cough. It’s important to have a balance,” says Dr Andy. “You don’t want it too humid or too dry. Good de-humidifiers will allow you to set them to a recommended humidity level.”

Asthma UK does not recommend ionisers

Asthma guidelines do not recommend the use of ionisers. There’s no evidence to show they improve symptoms, and they have been shown to make night time coughing worse.


Cookers can give out fumes when you’re cooking, so use an extractor fan if you’ve got one, or open a window. Use the highest setting at the back of the hob when you can, as this works best with the extractor fan. Let the fan run for 10 minutes after you finish cooking.

Gas cookers give out the most pollution. They give off nitrogen dioxide, and fine particles small enough to get into your lungs. These particles can make your airways swollen and inflamed, so you’re more at risk of asthma symptoms. So good ventilation in the kitchen is even more important if you cook with gas.

  • Get cookers checked and maintained at least once a year to make sure they’re not giving out too many fumes.
  • Make sure new cookers are well installed. And ask about ventilation too, for example an extractor fan or a cooker hood extractor, especially if it’s a gas cooker.
  • Kitchens should be well ventilated when cooking to prevent moisture and condensation building up.

Heating your home

Open fires

If you’re burning coal it gives off sulphur dioxide (SO2) which can trigger asthma or bronchitis.  Try ‘cleaner’ fuels which are labelled low in sulphur and less polluting. And choose wood with the ‘Ready to burn’ label so it gives out less smoke.

You can cut your risk by keeping flues clear and chimneys swept to allow the smoke to escape.

Wood burning stoves

Burning wood gives off tiny particles that can get into the airways. Breathing them in can make your airways inflamed, bringing on asthma symptoms. 

If you’re using a wood-burning stove, make sure it’s well maintained, and that you’re using dry woods (look for a ‘Ready to burn’ symbol). Newer designs are usually better and pollute less.

Central heating

This is a safer, cleaner option than open fires or wood burning stoves. It also helps avoid sudden temperature changes when you’re going from a warm room to a cold one.

But central heating can still give off some pollutants, especially if it’s an old boiler, or hasn’t been serviced for a while.

Look out for symptoms getting worse when you start using the heating in the winter - it could be that dust mites are on the increase.

Even if you’re using central heating it’s still a good idea to keep your home well ventilated, especially if you’re drying washing indoors. Washing on or near radiators creates a warm, humid environment where dust mites thrive.  

Aerosols and sprays

A lot of everyday products contain chemicals called volatile organic compounds (VOCs). These give off gases and can trigger asthma symptoms. A recent national study found that people with asthma were more likely to be sensitive to chemicals and fragranced products.

Often these are products with strong smells and perfumes. This could be household cleaning products like furniture polish, air freshener, carpet or oven cleaner. Or personal products like body sprays, perfumes, nail varnish and hairstyling products.

  • Choose products carefully - go for non-aerosol, low in VOCs and low fragrance
  • When you’re cleaning, use as little of the product as possible, and open windows to make sure there's plenty of ventilation.
  • Use a damp cloth instead of cleaning products whenever possible.
  • Always carry your reliever inhaler in case perfumes trigger symptoms when you’re out and about.

Furnishings and flooring

Carpets, furniture, shelving, and laminate flooring are sometimes made using volatile organic compounds (VOCs). These become a gas at room temperature, so your new furniture can give off fumes.

One of these VOCs is called formaldehyde. It’s mainly used in new wood products like flooring or furniture. It irritates the airways. It can also make your airways more sensitive to other triggers.

Formaldehyde can also be formed by other VOCs reacting with indoor pollutants like heating.

  • Choose new furniture or flooring which is low in VOCs and formaldehydes.
  • Ask the shop to unroll a new carpet and air it before you bring it home.
  • Keep rooms well aired when you first bring new furniture or carpets into the home.
  • Air any new bedding before you use it and consider using anti-allergy covers if you're sensitive to dust mites
  • Avoid using second hand mattresses which are high risk for dust mites.
  • Pets leave behind allergens. So, if you’re renting, or buying second hand furniture, think about getting carpets and furniture professionally cleaned. But keep in mind that even steam cleaning won’t get rid of all pet allergens.

Painting and Decorating

Some products used in decorating and DIY, like paints, glues and varnishes, contain volatile organic compounds (VOCs). These can be a trigger for some people with asthma. 

  • Look for paints labelled low in VOCs. You could also try low-odour, water-based paints. There are now lots available at big DIY stores. Newer paints have a lower VOC content than other paints.
  • Keep windows open to get some fresh air, whatever paints and products you use 
  • Always follow the product instructions to lower your risk of exposure to pollutants.
  • Open doors and windows if you’re working in a garage or shed where you’ve stored paints or solvents. And store paints and other products with lids on.

Housing repairs

There’s a link between poor housing and asthma, because of things like poor ventilation, heating, and mould and damp. So it’s important to make sure problems like these are sorted out as soon as possible. 

But getting work done in your home can trigger asthma too, from dust to the kinds of building materials used.

  • Find out what type of material is going to be used and whether it gives off VOCs. Try to use materials which emit a low level of formaldehyde and VOCs.
  • Make sure any insulation material is properly sealed once it’s installed because it gives off VOCs.
  • Ask your GP or asthma nurse if you should take more asthma medicines while there’s more dust and fumes at home.
  • Try to go out while the work is being done.
  • Stay with friends or family if you can while work is going on.

New homes

The trend for homes with open plan kitchens can increase indoor pollution.

While new homes are built to be air tight, they have to follow regulations on ventilation systems.

So, you might find trickle vents in windows which you can keep open, and extraction fans in kitchens, bathrooms and toilets. 


Thankfully cockroaches are a less common indoor trigger, particularly in the UK. But studies in the US suggest that poor housing in urban areas with cockroaches is a risk factor for people with asthma who are allergic to them.

If you’re a tenant, tell your landlord/landlady. If the problem is affecting your health, you might want to call in pest control.

Need more help and support with indoor triggers?

Call our Helpline on 0300 222 5800 Monday-Friday, 9am-5pm to speak to a respiratory nurse specialist about what you can do to reduce your risk of an asthma attack.

 Or you can WhatsApp them on 07378 606 728.


Last updated April 2020

Next review due January 2023

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Asthma action plans keep all your personal triggers and medicines tips in one place. Download one now to fill in with your doctor or nurse.