Apparatus and methods for protecting a patient from surgical site infection from airborne microbes during surgery. A sterile gas flow conditioning emitter for affixation onto an anatomical surface of a patient adjacent a site of incision is anatomically shape conforming for attaching a unidirectional coherent non-turbulent flow field of sterile gas substantially anatomically levelly on that anatomical surface and flowing the flow field in the direction of that site while essentially preventing ambient airborne particles from entering the interior of the flow field under the emitter to maintain the gas essentially sterile during passage over the site.