[AIVC, Air infiltration and ventilation glossary, 1992]:Air that is removed from a building or space. A proportion is often used for recirculation and added to incoming air. Alternatively, it is all exhausted to the outdoors, sometimes via an air-to-air heat exchanger or a heat pump.[EN 16798-3:2017, 3]:the airflow leaving the treated room and entering the air treatment system (ETA; colour Yellow)(see air, return)[EN 12792-2003, 145]:air flow leaving a treated space. (coded yellow)