Why oxygen concentrators produce less at altitude — the physics behind derating

Oxygen concentrators work by pulling in ambient air and using a molecular sieve (zeolite) to filter out nitrogen, concentrating the remaining oxygen for delivery. Ambient air pressure drops with altitude, meaning there's simply less total air — and less oxygen within it — available for the machine to process in each cycle, which reduces both the effective oxygen concentration and flow rate output.

Manufacturers publish altitude derating specifications for exactly this reason — most concentrators maintain rated performance up to a specified altitude (often around 6,000-10,000 feet depending on the model) before output measurably declines, and that specification is worth checking directly against your travel or relocation plans rather than assuming any concentrator performs identically everywhere.

For patients moving to or traveling extensively at higher elevation, this isn't a reason to avoid altitude — it's a reason to have flow rate reassessed by a physician at the destination altitude if the stay is extended, since the same prescribed LPM setting may not deliver equivalent oxygen saturation at 8,000 feet as it does at sea level.