Wednesday, August 18, 2021

What is breaking down in Philips CPAP machines?

Via the New York Times, bad news about Philips CPAP machines: 

Last month, the Food and Drug Administration warned of potential health risks that could be “life-threatening, cause permanent impairment and require medical intervention.” The potential harm comes from polyester-based polyurethane foam that dampens sound and vibration in the machines; it can degrade and result in a user’s breathing in chemicals or swallowing or inhaling black debris.

The agency said the possible risks of particulate and chemical exposure from the recalled devices included asthma, skin and respiratory-tract irritation and “toxic and carcinogenic effects” to organs including the kidneys and liver.

So here is how FDA explains it: 

Polyester-based polyurethane (PE-PUR) is a sound abatement foam used to reduce sound and vibration in these devices and other medical equipment. The PE-PUR foam in the affected Philips Respironics CPAP, BiPAP, and ventilator devices may:

  • Break down (degrade) into particles which may enter the device’s air pathway and be inhaled or swallowed by the user
  • Release certain chemicals into the device’s air pathway, which may be inhaled

These issues can result in serious injury, which can be life-threatening, cause permanent impairment, and require medical intervention to prevent permanent damage.

To date, Philips Respironics has received several complaints about the presence of black debris/particles within the device’s air pathway. Philips Respironics also has received reports of headache, upper airway irritation, cough, chest pressure, and sinus infection, which may be related to this issue, though the cause of the symptoms cannot be definitively linked.

The potential risks of particulate exposure include irritation to the skin, eye, and respiratory tract, inflammatory response, headache, asthma, and toxic or carcinogenic effects to organs, such as kidneys and liver.

The potential risks of exposure to chemicals released into the device’s air pathway from the PE-PUR foam include headache; dizziness; irritation in the eyes, nose, respiratory tract, and skin; hypersensitivity; nausea/vomiting; and toxic and carcinogenic effects.

The foam degradation may be exacerbated by high heat and high humidity environments, and by use of unapproved cleaning methods, such as ozone.

To date, there have been no reports of death as a result of these issues. 

I wonder what's breaking down in polyurethane foam? The particles irritating the respiratory system makes sense, but chemicals? Hmmm.... 


  1. I've seen polyurethane foam breakdown in old electronics equipment and packing cases, usually into a slimy sort of mush, so I don't think this is a new problem. It degrades to basically having zero elasticty, so you can compress it into a paste. I should actually go find some in my mountains of junks and run it for a GCMS scan in the lab, now I'm curious...

  2. It's really common for polymers to oxidatively degrade as they age. You've probably seen old lab hoses, bike tires, shoe soles, or other rubber and plastic objects crack and crumble.

    Small ozone generator machines have become very popular for cleaning the face masks and hoses of CPAP machines in the last few years, eliminating the need for manual washing with soapy water. I suspect the ozone may be contributing to the breakdown of the polymer. I once worked at a place where we had to have ServPro come in with their ozone generator machines to get rid of the odor after we had an experiment go wrong and smoke out the lab, and they warned us that the ozone may damage rubber and plastic materials in the building.


looks like Blogger doesn't work with anonymous comments from Chrome browsers at the moment - works in Microsoft Edge, or from Chrome with a Blogger account - sorry! CJ 3/21/20