Indoor asthma triggers

From cleaning products to wood-burning stoves, indoor triggers can set off your asthma symptoms at home, work or school

“The best way to cope with asthma triggers, indoors or out, is to take your preventer medicines regularly as prescribed,” says Dr Andy Whittamore, Asthma UK’s in-house GP. “And if you do notice symptoms getting worse, see your GP so you can update your asthma action plan.”

Common indoor triggers

Other steps that may help with indoor triggers

Common indoor triggers

“Cut down indoor triggers as much as you can, especially cigarette smoke, which can make you or your child more sensitive to other indoor allergens like house dust mitespets, and mould,” says Dr Andy Whittamore.

Open fires and wood-burning stoves

Burning wood gives off fine particles known as PM2.5. These are the same particles found in traffic pollution. These tiny particles can get into the airways. Breathing them in can make your airways inflamed, bringing on asthma symptoms.

Smoke from wood-burning stoves pollutes the air outside too. You may notice you’re affected if your neighbours have one.

If you’re burning coal it gives off sulphur dioxide (SO2) which can trigger asthma or bronchitis.  

Top tips:

  • Consider different forms of heating if smoke triggers your symptoms
  • Keep flues clear and chimneys swept to allow the smoke to escape
  • Keep your stove well-maintained. If it’s very old and giving out too much smoke, replace it. Newer designs are made to pollute less.
  • Use dry woods with a ‘Ready to burn’ symbol – wet wood gives off more smoke. Or try cleaner fuels which are low in sulphur and less polluting.
  • Good ventilation can cut the risk of your asthma being triggered by smoke.

Cooking and home heating

Heating and cooking appliances (especially gas cookers) give off fine particles and nitrogen oxides (NO2). Being exposed to these can make your asthma symptoms worse. It can also mean you’re more sensitive to other allergens, and to colds.

Central heating is a safer, cleaner option that open fires, wood burning stoves or gas or paraffin heaters without flues. It also helps avoid sudden temperature changes when you’re going from a warm room to a cold one. But it does give off pollutants, especially if you have an old boiler, or one which hasn’t been serviced for a while.

“Research actually suggests that asthma symptoms are easier to control for people who have central heating at home,” says Dr Samantha Walker, Director of Research and Policy at Asthma UK. “It gives out a dry heat, and asthma is worse in homes that are damp.”

Top tips:

  • Be aware of any new symptoms when you start using heating in the winter – and book an asthma review so you’re prepared
  • Keep your home well ventilated if you’re drying washing indoors on radiators to avoid build-up of humidity – dust mites multiply in warm, moist environments
  • Make sure boilers, gas cookers and heaters are well-maintained and serviced annually
  • Avoid heaters like gas heaters or paraffin heaters with no flue
  • New, efficient appliances and boilers are less polluting.

New carpets and furniture

Some people say the smell from new furniture or flooring triggers their asthma symptoms.

This is because carpets, furniture, shelving, and laminate flooring are sometimes made using volatile organic compounds (VOCs). These become a gas at room temperature, so your furniture can ‘give off fumes’. If there’s a strong smell there’s a good chance your new furniture contains VOCs.

Formaldehyde is a VOC found in new wood products like flooring or furniture. It irritates the airways and can also make your airways more sensitive to other triggers.

Formaldehyde can also be formed by other VOCs, in carpets or soft furnishings, reacting with indoor pollutants like heating.

Buying second hand sofas, rugs or carpets?

Keep in mind that the previous owner may have had pets. Pet allergens can hang around for a while after the pet has gone. Unfortunately steam cleaning or vacuuming are unlikely to get rid of all pet allergens.

Wondering whether to go for synthetic or feather pillows and bedding?

At the moment there’s no strong evidence to recommend one type of bedding over another for people with asthma. Consider what kind of bedding works best for you, as different people are triggered by both.

Top tips:

  • 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, and air any new bedding before use too
  • When you’re moving into a new place, check if there have been pets around. If pets trigger your asthma you might want to get the carpets and flooring in your new home professionally cleaned before moving in. But keep in mind that studies suggest this may not get rid of all pet allergens.
  • If you’re renting somewhere for a holiday, you could choose a place where pets aren’t allowed.

Household cleaning products

A lot of everyday cleaning products, like furniture polish, air freshener, carpet or oven cleaner, contain chemicals called volatile organic compounds (VOCs) that can give off gases and trigger asthma. Often these are products with strong smells and perfumes.

In fact, studies have shown that professional cleaners and others who use a lot of cleaning products are more likely to develop asthma.

Top tips:

  • Switch to low VOC products without perfume
  • Use liquid cleaning products rather than sprays so you’re less likely to breathe them in
  • Use as little of the product as possible, and open windows for fresh air when you’re cleaning
  • Use a damp cloth instead of cleaning products whenever possible.

Perfumes, hairsprays and deodorants – personal care products

People often tell us their asthma is trigged by perfumed products, such as body sprays, perfumes, nail varnish and hairstyling products. A recent national study found that people with asthma were more likely to be sensitive to chemicals and fragranced products.

Top tips:

  • Avoid using perfumed products
  • Always carry your reliever inhaler in case perfumes trigger symptoms when you’re out and about
  • Choose personal care products carefully – go for non-aerosol, low in VOCs and low fragrance.

Paints and DIY products

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.  

Top tips:

  • Look for paints with labels saying low in VOCs. You could also try low-odour, water-based paints. There are now lots available at big DIY stores.
  • Always keep windows open when you’re decorating
  • Open doors and windows if you’re working in a garage or shed where you’ve stored paints or solvents.

Building work and repairs

There’s a link between poor housing and asthma, because of things like damp and mould. 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.

For example, if you’re trying to sort out a damp problem with cavity wall insulation it’s worth knowing that some insulation materials give off volatile organic compounds (VOCs) which could make your asthma worse.

Top tips:

  • Find out what type of material is going to be used and whether it gives off VOCs
  • Make sure any insulation material is properly sealed once it’s installed
  • Ask your GP or asthma nurse if you should take more asthma medicines while there’s more dust and fumes at home
  • Stay with friends or family if you can while work is going on.


Thankfully cockroaches are a lesser known 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.

Top tips:

  • Don’t make food or water available for the pests – check for leaky pipes and bins that don’t close properly
  • If you know there are cockroaches about and you think it’s making your asthma worse, see your GP. They can help you deal with asthma symptoms. They may also be able to offer you allergy testing to confirm you have a cockroach allergy.
  • If you’re a tenant, tell your landlord. If the problem is affecting your health you might want to call in pest control.

Other steps that may help with indoor triggers

Opening windows and using fans 

Opening windows or using extractor fans helps clear fumes from fires, cookers, cleaning products or paints.

Good ventilation also reduces humidity – lower humidity means fewer house dust mites and mould spores.

If you’re thinking of using fans or extractor fans, clean them first if you haven’t used them for a while. They can gather dust which can get blown round the room.

When opening windows may not be a good idea for you...

  • If you live near a busy road remember that pollution from outside can get inside
  • And if you have a pollen allergy avoid opening the windows on high pollen days.

Air filters and purifiers 

Air filters and purifiers are designed to clean the air and may reduce the number of asthma triggers such as pet dander (flakes of skin), mould spores, dust and tobacco smoke particles.

Some people tell us having an air filter or air purifier helps them with their asthma symptoms. However more research is needed to prove this.

“Air filters can’t remove all allergens and even a few left behind can trigger asthma symptoms,” says Dr Andy Whittamore. “And for something like secondhand cigarette smoke, which comes top of the list of harmful indoor triggers, the best advice is always not to smoke, particularly around children.”

If you’re thinking of using an air filter or purifier, you need to:

  • Check what type of allergens it captures
  • Check that the air purifier is ozone-free. Some purifiers give out low levels of ozone which can make asthma symptoms worse
  • Clean and replace all filters when necessary.


Some people with asthma tell us that de-humidifiers help with asthma symptoms triggered by indoor triggers like dust mites and mould. This is because dust mites and mould are around more in damp, humid environments, and de-humidifiers keep the air dry.

But there isn’t much research 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 Whittamore. “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

Ionisers give out electrostatic charges to clean the air. Asthma UK doesn’t recommend using an ioniser because but there’s no evidence that they improve asthma symptoms.

A few research studies have shown that ionisers could increase night-time cough in children.

Speak to your GP or asthma nurse about what you can do to reduce your risk of an asthma attack. You can also call the Asthma UK Helpline on 0300 222 5800 Monday-Friday, 9am-5pm.

Or you can message them on WhatsApp on 07378 606 728.


Last updated June 2019

Next review due June 2022

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.