Perioperative design criterion has the standard two rating levels:
- Ultra Clean Air (high infection risk surgery) allowed the microbe is 10 CFU/m³
- Clean Air (normal risk of infection in surgery) allowed the microbe is 100 CFU/m³
CEN standard defines the operation time of ventilation dimensioning factor hall microbe (CFU/m³). The human is the only mikrobial source in the operating room, the number of people and clothing used effecting the microbe is a significant and thus directly affect the amount of the required airflow.
Find more information about standards in hospital in presentation by Jukka Vasara (link here).