CONCENTRATIONS OF AIRBORNE PARTICLES AND AIRBORNE MICROORGANISMS IN CONVENTIONALLY VENTILATED OPERATING-THEATERS UNDER VARIOUS AIR-EXCHANGE-RATES .2. MEASUREMENTS WITH SURGICAL ACTIVITY WITH RESPECT TO OPERATING PERSONNEL AND OPERATING PHASES

For measurements with surgical activity, it was investigated if the ai r-exchange-rate has a significant influence on airborne particle and b acteria concentrations in two conventionally ventilated operating thea tres. Next to that the influence of number of personnel in the operati ng theatre and the various operating phases were calculated (explanati on of variance). Statistical differences were found for airborne parti cle concentrations and a few for airborne bacteria concentrations in s upply and ambient air. From the hygienic point of view these differenc es must be considered to be irrelevant because of the little margin (l ess than one lg-step) between the values. The comparison of all air-ex change-rates as well as that between the two air-exchange-rates in the two operating theatres show that the number of personnel present in t he operating theatre has the most influence on airborne particle conce ntrations variance. Concerning airborne bacteria concentrations explan ation of variance by the treatment factors air-exchange-rate, personne l and operating phase is negligible. Summarizing the low (7.5 and 10/h ) and high (15 and 20/h) air-exchange-rates did not increase the expla nation of variance for airborne particle and bacteria concentrations a lthough the differences were on a significant level.