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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 increase when you’re in a building which has mould, it might be that you’re allergic to it. Or, more specifically, to the ‘seeds’ called 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.

On this page:

How do moulds and fungi affect asthma?

Normally, when people breathe in these spores, their immune system helps get rid of them by coughing or sneezing them out, or their eyes might water to wash the spores away. If you aren't sensitive to mould, you may never even experience a reaction. But for some people with asthma who are sensitive to mould spores, it can act as a trigger, causing asthma symptoms to get worse.

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, when wet clothes are dried next to a radiator or when the sun comes out after it's been raining on a warm day.

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

Around 37 per cent of people with asthma tell us mould and fungi can trigger their asthma. If you have cold-like symptoms that don't end when seasons change, you may be allergic to the spores of mould or other fungi.

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.

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.

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 reduce the risk of mould affecting your asthma

There are many different types of mould which release their spores at different times of the year. However, if you’re allergic to one mould spore you’re more then likely to be allergic to another, because they often have similar allergens. That means, 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 other things you can do.

  • Stay alert when there’s thunderstorms, as this breaks down both mould spores and pollen into smaller particles, which means they can irritate your airways more easily.
  • Damp wet weather can also make your house damp and wet, so, take extra care to prevent mould in your home by following the tips below when it’s rainy.
  • It’s very difficult to prevent encountering mould spores outside, but you could try to avoid areas (such as woodlands, parks, gardens or compost) that may contain them.
  • Make sure you’ve been taking your asthma medication – at the right times and in the right way – and you’re carrying your reliever inhaler if you do go out into nature.

Preventing mould in the home

As well as managing your asthma, you should prevent mould appearing to reduce the risk of triggering asthma symptoms. Try some of the tips shared below by 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 suspect mould is a trigger for your asthma, don't try to remove the mould by yourself. Ask someone else such as a friend, family member or a professional to remove it for you instead. Ideally, we recommend talking to your local council’s environmental health agency for advice on the best way to remove the mould.

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

You should always get a professional in if the mould covers more than one metre squared (3x3 feet) or is caused by rising damp, sewage or a problem in the building itself.

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 for 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 potential asthma triggers.