scope:

The present guideline VDI 4257 Part 2 specifies the requirements for active sampling of bioaerosols from exhaust air flowing through a defined crosssection. It defines general principles that have to be taken into account during an emission measurement of bioaerosols. Sampling of bioaerosols takes place in consideration of the isokinetic sampling according to VDI 2066 Part 11) under application of an emission impinger.

Separation of microorganisms in the impinger designed for a sample volume flow of 1 m3/h to 1,8 m³/h, or 16 ℓ/min to 30 ℓ/min, respectively, and has been tested with regard to various microorganisms within broad concentration ranges [4 to 7]. This method is accepted by convention as reference method for determination of total emissions under application of an out stack configuration according to VDI 2066 Part 1.

Sampling according to this guideline is a precondition for the extraction of a sample for the subsequent detection of moulds according to guideline VDI 4253 Part 2 and of bacteria according to VDI 4253 Part 3, and for determination of the total cell count according to VDI 4253 Part 4.