Air purifier diagnostics
Your air purifier is producing a smell
A musty smell is a saturated carbon filter or damp media and needs a filter change. A burning or hot-plastic smell is electrical and means switch it off at once.
Important
Before you open anything
- A burning or hot-plastic smell means unplug at the wall immediately. Do not wait to see whether it clears.
- Ozone is a respiratory irritant, especially for asthma sufferers. If your unit has an ioniser you can switch off, and you can smell it, switch it off.
Does this match your symptoms?
- Musty or sour smell from the outlet
- Sharp, slightly metallic smell like chlorine
- Burning or hot-plastic smell
- New unit smells of chemicals or plastic
Work through the causes in this order
Ordered by how often each turns out to be the real cause — not by what it costs to fix. 3 of these cost nothing to resolve.
- Most commonYou can fix this₹800 – ₹2,000
1. Saturated activated-carbon filter
How to confirm it
Carbon adsorbs odours until it is full, then stops — and in warm conditions can begin re-releasing what it captured. If the smell resembles the odours the unit has been working on, in a kitchen or a smoking household, this is it. Carbon typically saturates in 6-12 months, faster in heavy-odour environments.
The fix
Replace the carbon filter. Carbon cannot be washed or regenerated at home; washing simply wets it and makes the smell worse.
Part: Activated-carbon filter
- CommonYou can fix this₹1,500 – ₹4,500
2. Damp filter media or mould
How to confirm it
A musty, cellar-like smell, most common after monsoon, in a humid room, or where a HEPA has been washed against the maker's instructions. Remove the filter and smell it directly — if it is the source, it is unmistakable.
The fix
Replace the affected filter. Do not attempt to dry and reuse a HEPA that has been wet: the media is damaged and any mould growth is now inside it. Run a dehumidifier if the room is chronically damp.
Part: HEPA and/or carbon filter
- CommonYou can fix thisFree to fix
3. Ozone from an ioniser or UV stage
How to confirm it
A sharp, faintly metallic smell reminiscent of the air after a thunderstorm. Switch off the ioniser or UV function — if the smell disappears within a few minutes, that was the source.
The fix
Leave the ioniser off. Ozone is a respiratory irritant and offers no filtration benefit that the HEPA is not already providing better. If the unit cannot run without its ioniser, that is a genuine mark against it.
Part: None
- CommonYou can fix thisFree to fix
4. New-unit off-gassing
How to confirm it
A plastic or chemical smell in the first few days of a new purifier, fading steadily. Normal for new plastics and new filter media.
The fix
Run it in a well-ventilated room for a day or two. If a strong chemical smell persists beyond a week, raise it with the seller.
Part: None
- RareTechnician jobFree to fix
5. Electrical fault
How to confirm it
Burning, scorched or hot-plastic smell. Do not investigate this while the unit is running.
The fix
Unplug immediately and stop using it. Have it inspected, or replace it if out of warranty. An electrical smell from a device that runs unattended overnight is not something to monitor and see.
When to stop and call a technician
- Any burning or electrical smell — unplug first, then arrange inspection
- A musty smell that persists after replacing both the HEPA and the carbon filter
- Visible mould growth inside the unit housing
Costs shown are indicative bands for India, published so you can sanity-check a quote — they are not quotations, and they vary by brand, city and whether the technician is brand-authorised. Last reviewed 2026-08-08.