The patient's external environment plays a significant, and in some cases dominant, role in his or her infection risk. The use of ultraclean air for certain procedures, as well as avoidance of hypothermia have been proven to reduce the risk of infection. There is no data to support the routine use of surgical masks (by surgeons or staff), ventilating helmets, or routine cleaning of all environmental surfaces in between cases. More research needs to be done in order to determine whether OR design changes, in addition to increasing OR efficiency and thus reducing case times, can also reduce infection rates. Further research is also needed to determine whether or not double gloves and/or the use of antiseptic scrubbing in addition to painting are efficacious.