Introduction
Routine measuring air quality by air sampling has been questioned since there is a poor association between air quality and nosocomial infections. In Switzerland, the standard called “Good practice for the preparation of sterile medical devices-2005”defines air quality standards determined by particle Class 8 (Norm EN ISO 14644-1) in idle state (nobody is in the room) and by microbiological test in operation (upper limit. 200 cfu/m3) to detect malfunction of air conditioning. The objective of this study was to investigate qualitatively and quantitatively the microbiological loads before and during work session in CSS of the University Hospital Basel.