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Moulds and fungi

Mould spores can trigger asthma symptoms, here’s what to do about it.

Moulds and fungi are common and often quite small, but research shows they can have a big impact on your asthma symptoms.

If you notice your asthma symptoms get worse when you’re in a building which has mould, it might be that you’re allergic to the spores that moulds and other fungi release into the air.

If that’s the case, it’s important you do all you can to look after your asthma and get rid of any mould.

How do moulds and fungi affect asthma?

When someone with an allergy to mould breathes in mould or fungi spores, their immune system over-reacts with coughing, sneezing or watery eyes. 

If you aren't sensitive to mould, you may never have a reaction to it. But for some people with asthma who are sensitive to mould spores, it can act as a trigger, causing asthma symptoms to get worse.

Who is most likely to be affected by moulds and fungi?

Around 42% of people with asthma tell us mould and fungi can trigger their asthma.

People with asthma who are more likely to have their asthma triggered by fungal and mould spores include:

babies and children
• elderly people
• people with existing skin problems, such as eczema
• people with a weakened immune system
• people with severe asthma.

If you’ve noticed cold-like symptoms - sneezing, blocked nose, coughing - in warm, damp environments, or outside in parks or woods, it could be that you’re allergic to the spores of mould or other fungi.

What mould looks like and where to find it

Mould is usually noticeable and can be white, black, yellow, blue or green in colour. It can also have a velvety, fuzzy or rough appearance, and usually has a musty or stale smell.

Mould grows in damp or musty conditions, so common places for it to grow in houses are on wallpaper, flooring, behind wall tiles and on window frames.

Outdoors, mould can grow on rotting logs and fallen leaves, in compost piles and on grasses and grains. You're more at risk from them in warm, humid weather, for example when the sun comes out after it's been raining on a warm day. There's less of a risk on cold, dry windy days.

Indoors, spore numbers increase when there's a sudden rise in temperature in a moist environment, such as when central heating is turned on in a damp house, or when wet clothes are dried next to a radiator. 

Although mould and fungi themselves are obvious, the spores they release are often invisible to the naked eye. That means your safest bet is avoiding mould and fungi so you don’t get an allergic reaction to their spores.

How to cut the risk of mould affecting your asthma

There are many different types of mould which release their spores at different times of the year. 

Mould spores tend to peak in summer and autumn. However, if you’re allergic to one mould spore you’re more than likely to be allergic to another. So, if you have asthma you need to be aware of mould all year round.

The best thing you can do is to keep your asthma as well managed as possible. You can find useful tips and advice here.

Even though it’s hard to avoid mould entirely, there are a few things you can do.

  • Damp wet weather can also make your house damp and wet. Take extra care to prevent mould in your home by following the tips below when it’s rainy.
  • It’s very difficult to avoid mould spores outside, but you could try to avoid areas such as woodlands, parks, or gardens that may contain them. You might find this is more of a problem for you in the autumn when there are lots of fallen leaves around.
  • Make sure you always take your preventer medicine as prescribed, and in the right way. And don't forget to take your reliever inhaler with you when you go out. 

Preventing mould in the home

As well as managing your asthma, try to prevent mould appearing in the first place to reduce the risk of triggering asthma symptoms.

Try some of these tips from people with asthma:

  • Check for any water leaks under your sinks, fridge, dishwasher and washing machine, as well as around the toilet, bathtub, shower and hot water tank.
  • Keep the garden clear of fallen leaves and other debris.
  • To prevent mould building up indoors, ensure your house is well ventilated by opening windows regularly.
  • When showering or cooking, use your extractor fan or open a window, and keep doors closed to prevent damp air spreading through the house. Keeping the lid on saucepans can help too.
  • Try not to dry clothes indoors, store clothes in damp cupboards or pack clothes too tightly in wardrobes.

Getting rid of mould

If you think mould is a trigger for your asthma, don't try to get rid of the mould by yourself. Ask someone else to remove it for you. And get advice from your local council’s environmental health agency. 

You should always get a professional in if the mould covers more than one metre squared, or is caused by rising damp, sewage or a problem in the building itself. 

Whatever you do, remember to keep the room ventilated when the mould is being removed as there may be spores lingering in the air. The cleaning chemicals used could also trigger your asthma.

You can find useful advice on removing mould safely on the NHS website.

If your rented house has mould

If you're living in rented or council accommodation and your home is constantly mouldy and damp, even after regular cleaning, search ‘mould’ on housing charity Shelter’s website. You can find information on how to talk to your landlord or local housing department about the problem.

You can also contact Shelter on 0808 800 4444. Calls are free from UK landlines and main mobile networks.

Mould at work

If you notice mould in your work place, make sure you talk to your employer, supervisor or health and safety representative. Our page on asthma at work explains how to talk to them about your asthma triggers.

Last updated March 2018

Next review due March 2021

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.