Efficiency of “Biotest RCS” as a Sampler of Airborne Bacteria

Abstract

This paper reviews the mathematical basis provided by the manufacturer of the “Biotest RCS“ air sampler. Eight published comparisons of this device’s efficiency with that of slit samplers arrived at conflicting conclusions. The RCS’s efficiency was overestimated by those evaluators who used the manufacturer’s air sampling rate of 40 liters per minute (Lpm). According to the calibration equation, however, the 40 Lpm rate only applies to particles 4 micrometers in effective diameter; larger airborne particles must be regarded as having been deposited from larger volumes of air. Since the bacteria-containing particles which cause problems in aseptic filling rooms are much larger than 4 ¼m, the equation requires the use of sampling rates larger than 40 Lpm, which leads to lower values for the concentration of airborne bacteria. This observation may have an effect on acceptable sanitary standards in clean rooms where the RCS is used to evaluate the environment.