Can mould really trigger asthma?

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If you have, or a loved one has, asthma, of course one of your worries might be identifying possible triggers to help keep it controlled.

Recap – triggers

Triggers include mould spores, smoke, cold air, exercise, infections and others.

Recap – symptoms

Wheezing, tight chest and coughing.

So let’s talk more about the triggers…

Smoking – yourself, or ‘secondhand’ smoke from someone else.

If you smoke, consider quitting.

If someone you spend time close to smokes, encourage others to quit.


These are tiny bugs which are in many homes. They are not visible with the human eyes, and can trigger asthma attacks. So how can we deal with these invisible critters?

  • Use dustmite prevention mattress/pillow covers
  • Not using down-filled pillows/quilts
  • Washing your bedding weekly
  • Vacuuming carpets/floors regularly with a vacuum containing a HEPA filter
  • Keeping humidity levels low, around 30-50%.

Air pollution

Pollution can come from many sources including cars, factories and aeroplanes. Breathing in too much of this smoke can cause an asthma attack. You can check air quality forecasts to help plan your activities when air pollution levels are lower.

ULEZ – London’s ultra low emission zone was expanded on 29 Aug 2023 to cover all London boroughs. This is to bring cleaner air to all Londoners.

Cockroaches and other pests

To control pests at home:

  • Remove as many left over food and water sources
  • Store food in airtight containers
  • Keep trash in a closed container
  • Keep floors, sinks, tables clean of clutter
  • Seal cracks/openings in the kitchen
  • Use pesticide baits/traps safely
  • Avoid using sprays as they can cause asthma attacks.


Furry pets can trigger asthma attacks if you are allergic to them.

If you think a pet is causing this issue, you may want to find the pet a new home.

If this is not possible, keep pets out of bedrooms, wash them, use an air cleaner with HEPA filter, and allergy proof mattress/pillow covers.

What about mould?

Surely you must have heard about the tragic case of the two-year-old who died from prolonged exposure to mould in his family’s flat? Awaab Ishak died in 2020, eight days after his second birthday, as a direct result of black mould in the flat he lived in. Read about it here.

Breathing in mould can trigger asthma attacks even if you’re not allergic to mould.

How can you reduce mould?

  • Dry damp or wet items within 24 to 48 hours to prevent mould growth.
  • Fix water leaks, such as leaky plumbing, which let mould grow behind walls and under floors as soon as you can
  • Replace absorbent materials, such as ceiling tiles and carpet, if mould is present
  • Use an air conditioner or dehumidifier to maintain low indoor humidity
  • Get a small tool called a hygrometer to check humidity levels and keep them as low as you can—no higher than 50%. Humidity levels change over the course of a day, so check the humidity levels more than once a day.
  • Scrub mould off hard surfaces with detergent and water. Dry completely
  • Empty and clean refrigerator and air conditioner drip pans regularly.
  • Run the bathroom exhaust fan or open the window when showering.


Some cleaning/disinfectant products can trigger asthma. Try to stay away when cleaners or disinfectants are being used or right after their use.

Other triggers

Other triggers can include infections such as flu, and colds. Acid reflux, exercise, weather (high humidity and thunderstorms), breathing in cold air, and some foods/fragrances. Strong emotions that cause fast breathing can also lead to an asthma attack.

More information

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