In the OR the ETT will be sterile, as will all the other instruments used. Otherwise, in a febrile or immunocomprised patient (which many in OR might be) the risk of introducing a secondary infection is increased. It would be considered very poor practice in an OR environment not to have all instruments sterile and work as aseptically as possible eg. face masks, sterile gloves. In an emergency situation, away from ER, although a sterile ETT may be used, the conditions are not aseptic. The principle is to use sterile instruments where possible.