Machine and humidifier
CPAP Smells Bad: Musty, Plastic or Burning Smell Explained
A musty or sour smell from a CPAP usually comes from a water chamber, mask or hose that needs cleaning or from water left standing. A burning smell, smoke or any unusual odor is different: the FDA tells DreamStation 2 users to unplug the machine and stop using it. Clean with mild soap and water as your manual directs, and do not rely on ozone or UV cleaners.
Signs
- Musty or mildew smell in the air
- Sour smell from the water chamber
- Plastic smell from new equipment
- Burning or hot electrical smell
- Visible film or spots in the chamber or hose
Common causes
- Dirty water chamber
- Fisher and Paykel recommend cleaning the humidifier daily with warm water and mild detergent and a thorough clean at least every two weeks to prevent mold and mineral buildup.
- Water left in the tank
- Standing water grows germs. Fisher and Paykel recommend refilling with fresh distilled water daily.
- Dirty mask or tubing
- The FDA explains that germs from your mouth and throat, and germs on your skin, can get into the mask and hose, and that dust and mold can collect too.
- Overheating or electrical problem
- The FDA's November 28, 2023 safety communication on Philips DreamStation 2 reported burning smells, smoke and other signs of overheating that may relate to an electrical or mechanical malfunction.
- Recalled Philips foam
- Philips recalled certain CPAP, BiPAP and ventilator machines in June 2021 because the PE-PUR sound foam can break down. The FDA says black pieces of foam, or chemicals that are not visible, could be breathed in or swallowed.
Fixes to try, easiest first
Unplug right away for any burning smell or smoke with your clinician
If you smell burning, smoke or any unusual odor, the FDA tells DreamStation 2 users to unplug the machine and not use it. The same applies if its appearance changes, its performance changes, water spills into it, or it makes unusual sounds. Report it to your provider and the manufacturer.
Empty and refill the water daily
Pour out leftover water every morning, let the chamber air dry, and refill with fresh distilled water at bedtime.
Wash the chamber, mask and hose
Use mild soap and warm water as your user guide directs, rinse well and let everything air dry. The FDA says most masks, hoses and humidifier tanks can be cleaned this way, and some manufacturers recommend diluted vinegar.
Replace the filter
Air filters trap dust and odors. Replace or rinse them as often as the manufacturer recommends.
Air out new parts
A new mask or hose can have a plastic smell at first. Wash it before first use following its instructions.
Skip ozone and UV cleaners
The FDA says machines advertised to clean or disinfect a CPAP are not necessary. In February 2020 the FDA warned that ozone and UV light cleaning products were not legally marketed for this use. Ozone in particular has been linked to breathing complaints.
Check whether your Philips machine was recalled
If you own a Philips device, check the serial number on the Philips recall site. The FDA announced on April 9, 2024 that a federal court consent decree, with limited exceptions, restricts the production and sale of new CPAP and BiPAP machines at several Philips Respironics facilities in the United States until certain requirements are met.
Stop and call your provider for any burning smell, smoke or overheating, and talk to your doctor before stopping therapy. See your doctor if you have a new cough, breathing problems, sinus symptoms or headaches that started with a smelly machine, or if you have used a recalled Philips device and are worried about exposure.
Supplies that can help
Plain, mild dish soap is the cleaning agent most CPAP makers and the FDA point to for masks, tubing and humidifier chambers.
A long, flexible brush sized to reach the full length of CPAP tubing so you can scrub the inside, not just soak it.
Distilled water is what most CPAP humidifier chambers are meant to be filled with, because it leaves little or no mineral scale behind.
The air inlet filter keeps dust and lint out of the machine and your airway; it is a cheap part that needs regular replacement.
Pre-moistened wipes for a quick daily wipe of the mask cushion, mostly to remove skin oils between proper washes.
The removable water tank of a CPAP humidifier; it wears and needs replacing, especially if it cracks, clouds or leaks.
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Mask types this applies to
Frequently asked questions
Why does my CPAP air smell musty?
A musty smell almost always means something needs cleaning, most often the water chamber or hose. Empty the water daily, wash parts in mild soap and water, and replace the filter.
Do I need a CPAP sanitizer machine?
No. The FDA says devices that claim to clean CPAP machines are not necessary, and that soap and water per your manual is the standard method.
My CPAP smells like burning plastic. Is it safe to use?
No. The FDA tells DreamStation 2 users to unplug and stop using the machine if they smell burning, smoke or unusual odors. Contact your provider and the manufacturer before using it again.
How do I know if my Philips CPAP is part of the recall?
Philips recalled certain machines in June 2021 over foam breakdown. Check your serial number on the Philips recall page and follow the FDA's recall information.
Sources
Last reviewed October 11, 2026. How we research · Report an error