Why Mould Smells Musty & How to Permanently Get Rid of It

Written by: Karan Mithi

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Published on

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Time to read 6 min

If you've ever walked into a damp basement, musty bathroom, or a room that hasn’t been aired out in a while , you’ve likely noticed the unmistakable stale, musty smell of mould . This unpleasant odour is more than just a nuisance—it’s a sign of active mould growth and poor indoor air quality .

Mould thrives in damp, poorly ventilated spaces , releasing airborne spores and microbial compounds that create that lingering musty smell . Ignoring it won’t make it go away—in fact, prolonged exposure can lead to health problems, allergies, and respiratory irritation .

In this guide, we’ll explore:
✔️ Why mould smells musty and what causes the odour
✔️ The health risks of exposure to mouldy air
✔️ How to permanently eliminate mould and its smell 

Why Does Mould Smell Musty?

The musty smell of mould is caused by MVOCs (Microbial Volatile Organic Compounds)gaseous chemicals released by active mould colonies . When mould grows on surfaces, it breaks down organic material, releasing odour-causing compounds into the air .

Common Causes of Mould Odours:

✔️ High humidity & moisture buildup – Mould needs moisture to grow and release MVOCs.
✔️ Poor ventilation – Trapped air allows musty smells to linger.
✔️ Hidden mould growth – Mould may be inside walls, carpets, or HVAC systems .
✔️ Damp furniture & fabrics – Upholstery and curtains can absorb mould spores and odours.

Even after cleaning visible mould , the odour can linger if spores are still present in the air or if the source of moisture hasn’t been addressed .

Is the Musty Smell of Mould Harmful?

Yes. The presence of a musty odour indicates active mould growth , which can negatively impact health, especially for people with allergies, asthma, or weakened immune systems .

Health Risks of Exposure to Mould Odours:

⚠️ Respiratory issues – Mould spores can irritate airways , triggering wheezing, coughing, and shortness of breath.
⚠️ Allergy symptoms – Sneezing, itchy eyes, nasal congestion, and skin irritation are common.
⚠️ Sinus infections & headaches – Prolonged exposure can lead to chronic sinus issues and fatigue .
⚠️ Weakened immune function – Mycotoxins from mould can suppress immune response, increasing susceptibility to infections.

If you notice a persistent musty odour , it's a sign that mould is present and needs to be addressed immediately .

How to Permanently Eliminate Mould and Its Smell

To get rid of mould odours permanently, you need to eliminate the mould at its source and remove lingering airborne spores . Follow these steps:

Step 1: Find & Remove the Mould Source

✔️ Inspect walls, ceilings, and floors – Look for visible mould growth in damp areas.
✔️ Check HVAC systems – Mould can spread through air conditioning and ventilation systems .
✔️ Don’t forget hidden spots – Mould often grows behind furniture, under carpets, or inside walls .

How to Clean Mould Properly:
✅ Use vinegar or hydrogen peroxide – These kill mould at its root (unlike bleach, which only removes surface stains).
✅ Scrub affected areas thoroughly – Use a stiff brush for porous surfaces.
Dispose of contaminated materials – Severely mouldy carpets, drywall, or insulation should be replaced .


Step 2: Use an Air Purifier to Remove Airborne Mould Spores

Even after cleaning mould from surfaces , spores can remain suspended in the air , causing recurring odours and health issues . A high-quality air purifier is the best way to eliminate airborne spores and MVOCs .

What to Look for in an Air Purifier for Mould & Odours:

True HEPA Filter – Captures 99.97% of mould spores , preventing them from spreading.
Activated Carbon Filter – Absorbs musty odours and MVOCs from the air.
No Ozone Emission – Some air purifiers produce ozone , which can irritate lungs and worsen symptoms.
Continuous Air Circulation – Running the air purifier consistently helps eliminate mould odours over time .

Placing an air purifier in high-risk areas like bathrooms, basements, and kitchens will significantly reduce mould odours and improve indoor air quality .


Step 3: Reduce Moisture & Improve Ventilation

✔️ Use a dehumidifier – Maintain indoor humidity levels at 30–50% to prevent mould growth.
✔️ Fix leaks and seal cracks – Mould thrives in hidden moisture sources .
✔️ Use exhaust fans in bathrooms & kitchens – Removes steam and excess humidity.
✔️ Increase airflow – Keep windows open when possible to prevent stale, damp air buildup .

Since mould needs moisture to grow , eliminating excess humidity is crucial to preventing future growth .

Where to Place an Air Purifier for Maximum Effectiveness

To eliminate mould spores and musty odours , place air purifiers in the most vulnerable areas of your home:

✔️ Bathrooms – Steam from showers encourages mould growth.
✔️ Basements & attics – Poor ventilation leads to trapped moisture.
✔️ Kitchens & laundry rooms – Cooking steam and damp laundry contribute to humidity.
✔️ Bedrooms – Mould spores in bedding or carpets can affect sleep quality and breathing .

For best results , run your air purifier continuously in affected areas .


Air purifier
  1. "How a True HEPA Filter Removes 99.97% of Allergens & Pollutants"

  2. "Why True HEPA Filtration is Essential for Allergy and Asthma Relief" 

Who Benefits the Most from Removing Mould Odours?

✔️ People with Allergies & Asthma – Mould spores trigger respiratory issues and increase inflammation .
✔️ Children & Elderly Individuals – More vulnerable to mould-related health risks .
✔️ Homeowners in Humid Climates – Constant moisture promotes mould growth year-round .
✔️ Anyone Experiencing Persistent Musty Odours – If the smell keeps coming back , it's a sign that mould spores are still present .

If you or your family members experience allergy symptoms or musty odours , investing in an air purifier and proper moisture control is essential.

How to Prevent Mould from Returning After Removing the Smell

Even after cleaning visible mould and removing musty odours , the problem can come back if you don’t take long-term prevention measures . To ensure mould doesn’t return, follow these steps:

✔️ Keep Humidity Levels Low – Maintain indoor humidity below 50% using a dehumidifier or air conditioner .
✔️ Use a HEPA Air Purifier Continuously – Keep it running to trap airborne mould spores before they settle .
✔️ Improve Ventilation – Open windows when possible and use exhaust fans in bathrooms, kitchens, and laundry rooms .
✔️ Fix Leaks & Address Water Damage Quickly – Even small leaks can lead to major mould problems.
✔️ Regularly Inspect & Clean High-Risk Areas – Check bathrooms, basements, and attics for any signs of moisture buildup.

By combining air purification, humidity control, and regular maintenance , you can keep your home mould-free and permanently eliminate musty odours .


Frequently Asked Questions

Does a musty smell always mean mould is present?

Yes. A persistent musty odour is often a sign of active mould growth , even if you can’t see it .


Can an air purifier remove mould smells completely?

Yes! A True HEPA & activated carbon air purifier removes airborne mould spores and MVOCs , eliminating musty odours over time.


How long does it take to remove a mould smell?

✔️ After cleaning – The smell may linger for a few days .
✔️ With an air purifier – It can significantly reduce odours within hours to days .

What’s better for mould control: an air purifier or a dehumidifier?

Air Purifier – Removes airborne spores and musty odours .
Dehumidifier – Reduces moisture levels to stop mould from growing .
💡 Using both together is the best way to eliminate mould permanently .



Can mould odours come back after cleaning?

Yes. If the source of moisture or spores isn’t removed , the smell will return .

Final Thoughts: Say Goodbye to Musty Mould Odours for Good

The musty smell of mould isn’t just unpleasant—it’s a warning sign of poor indoor air quality. By eliminating the source, purifying the air, and controlling humidity , you can:

✅ Remove musty odours permanently
✅ Improve respiratory health & reduce allergies
Prevent mould from coming back

🛒 Looking for the best air purifier to eliminate mould odours? Sho