That musty smell is not dirt — it is microbial gas, and here is how to remove it
24 July 2026 · 5 min read · DRYAir Dehumidifiers
The short answer
A musty smell is caused by microbial volatile organic compounds — gases released by mould and bacteria as they digest damp material in walls, fabrics and wood. Air fresheners only mask these gases. The smell disappears permanently when relative humidity is held at 45–55%, because the microbes stop metabolising and producing them.
Everyone recognises the smell. It lives in built-in wardrobes, unused rooms, bathroom cupboards, cars parked overnight, and on clothes that were dried indoors during the monsoon. Most people treat it as a cleanliness failure, which is why the usual response is more washing, more air freshener, and eventually camphor balls.
What you are actually smelling
The odour is made of microbial volatile organic compounds — MVOCs. These are gases given off by mould and bacteria as they feed on damp material: cotton, leather, timber, paper, plaster, upholstery foam. The smell is literally the by-product of something living and eating inside your soft materials.
Two implications follow. First, an air freshener adds a second smell on top of the first — the microbes carry on regardless. Second, the smell is an early warning: it usually appears before you can see any mould, which means it is one of the most useful signals you have.
Why it concentrates in wardrobes and closed rooms
Wardrobes are the perfect trap: no airflow, packed with absorbent fabric, and usually built against an external wall that runs cooler than the room. Moisture settles there, the clothes hold it, and MVOCs build up in the enclosed space until you open the door and get the full concentration at once.
Guest rooms, storerooms and unused bedrooms behave the same way. Closing a room to keep dust out also stops air exchange, so humidity climbs.
Removing the smell permanently
- 1Empty the affected space fully — wardrobe, cupboard or room.
- 2Wash affected fabrics at 60°C where the care label allows; sun-dry them completely if you can.
- 3Wipe down hard surfaces and check for any visible mould, especially at the back and along the base.
- 4Run a dehumidifier in the room set to about 50%, with wardrobe and cupboard doors open for the first two or three days.
- 5Return items only once the space is genuinely dry, and leave a small airflow gap behind furniture.
Most households report the smell fading within two to three days and gone within a week. It stays gone as long as humidity stays controlled — which is the part camphor balls and fresheners were never able to do.
The laundry problem
Indoor-dried laundry is a specific Sri Lankan version of this. Clothes that take many hours to dry in humid air begin to develop bacterial growth before they finish, which is where the sour, musty note on 'clean' clothes comes from. Drying the room air fixes the clothes and the room together — several of our units include a dedicated clothes-drying mode that will dry a rack of laundry indoors in under an hour rather than a full day.
Fix it at the source
Hold your rooms at a healthy 45–55%
DRYAir dehumidifiers set a target humidity and hold it automatically — day, night and right through the monsoon. Islandwide delivery, local service since 2010.
Frequently asked questions
Why do my clean clothes smell musty?+
Because they dried too slowly. In humid air, damp fabric supports bacterial growth before it finishes drying, and those bacteria produce the musty odour. Faster drying — or drier room air — prevents it.
How long does a dehumidifier take to remove a musty smell?+
Typically two to three days for the smell to fade noticeably and about a week to clear entirely, assuming affected fabrics have been washed and the space is left open to dry.
Does the musty smell mean I have mould I cannot see?+
Usually yes. MVOC odour is produced by active microbial growth, and it often becomes noticeable before visible patches appear — commonly behind furniture, inside cushions or under mattresses.
Will camphor balls or charcoal fix it?+
Only temporarily. Camphor masks the smell and charcoal absorbs a little of it, but neither stops the mould and bacteria producing it. Once the absorbent is saturated the smell returns.
Keep reading
Written by the DRYAir team — dehumidifier specialists in Sri Lanka since 2010. Questions about your own space? Call +94 75 666 00 00 any time, or message us on WhatsApp. This guide is general information, not medical advice — for persistent symptoms, please speak to your doctor.