Assertion: oxygen | /r/HasProperty | absent
Facets:
Source sentences:
text: On land they are used in industrial applications where poisonous gases may be present or oxygen may be absent, firefighting, where firefighters may be required to operate in an IDLH atmosphere for extended periods, and in hospital anaesthesia breathing systems to supply controlled concentrations of anaesthetic gases to patients without contaminating the air that the staff breathe, and at high altitude, where the partial pressure of oxygen is low, for high altitude mountaineering.