Bacteriological evaluation of a laminar cross-flow tunnel for surgery under operational conditions.

A transportable surgery cross-flow unit has been tested under ;operational conditions'. By the use of artificial aerosols and a volunteer surgical team, or dummies, it was found that, at an air velocity of 0.45 m./sec., a detectable transfer to above the table occurred only when quite highly concentrated aerosols (of more than 10(3.6) bacteria/m.(3) of air or more) existed underneath the table. The short disappearance time under these conditions and the quite stable flow pattern above the table found when a surgical team was working, standing along both sides of the table, make it unlikely that an aerosol of detectable concentration can develop during surgery, at this site. The chance that particles, liberated from the heads of the surgical team, settle on the table, was found to be strongly reduced when a cross-flow tunnel operated at an air velocity of 0.45 m./sec. The transfer from outside the unit to the inside was prevented by closing the upper part of the open front side.