vitiated air

vi·ti·at·ed air

air containing a reduced percentage of oxygen.
References in periodicals archive ?
Transverse ventilation uses both a supply duct system and/or an exhaust duct system to uniformly distribute supply air and/or collect vitiated air throughout the length of the facility.
This atrium introduces daylight into the centre of the library, gives legibility to the vertical circulation, and ventilates vitiated air upwards out of the building, contributing to the building's impressive environmental rating.
It accounts for the fact that only the critical zone--a zone that requires the highest fraction of ventilation air in its supply air--will produce fully vitiated air (where fully vitiated air is air from zones that receive exactly the minimum ventilation rate required by the standard, and ventilation air is a combination of outdoor air and recirculated return air that is not fully vitiated).