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 laboratory, consult the specific laboratory procedure for the number of blanks to be submitted. (2)

Field Blanks Field blanks are simply unopened, fresh media samples that are handled in every way the same as field samples, including labeling, except that no air is drawn through the sampler. The recommended practice for the number of field blanks is to provide two field blanks for every 10 samples with a maximum of 10 field blanks for each sample set.

4.

PREPARATION, IDENTIFICATION, CULTURABLE BIOAEROSOLS a.

AND

ENUMERATION

PROCEDURES

FOR

Sample Preparation Inoculated agar plates are incubated at the appropriate temperature for times ranging from hours for a fast-growing bacterium to develop a microcolony; to days for a fungus to develop into a visible colony, and perhaps sporulate; to weeks for an organism such as drug resistant Mycobacterium tuberculosis to produce visible colonies [ATS 1990]. As a rule, plates are incubated at the temperatures shown in Table III [ACGIH 1989, Fungi and Bacteria; Baron and Finegold 1990].

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NIOSH Manual of Analytical Methods