ISO 80601-2-69:2014 includes specific requirements that mitigate the risk of fire associated with oxygen therapy.
In summary: The applied part (nasal cannula and tubing or mask and tubing) shall be provided with a means to extinguish a tubing fire and isolate the oxygen flow.
This should be fitted close to the patient. A means to prevent propagation of fire into the oxygen concentrator outlet shall be provided. The means can also stop the flow of oxygen but it doesn’t have to. If a bubble humidifier is fitted to the concentrator, the means must protect the bubble humidifier too