MICROBIAL ANALYSIS OF DEPOSIT DUST ON SURFACES IN BUILDINGS OFFICES EQUIPPED WITH CENTRAL AIR- CONDITIONING INSTALLATIONS: PROPOSED MICROBIAL PRACTICAL VALUES WITH A NEW STANDARDIZED METHOD

摘要

A method for monitoring the microbiological composition of deposit dust in buildings equipped with HVACs (Heating, Ventilation, and Air Conditioning) is described. A piece of glass, firstly washed with an alcohol solution was placed on furniture for 7 days. Afterwards, 5 RODAC plates, were applied to the glass, and incubated at appropriate temperatures. From July 1999 to August 2000, more than 180 samples were made in 19 buildings for bacteria and in 24 buildings for moulds. Total bacteria and total moulds were counted. Main moulds were identified. Values situated between centile 50 and 75 were considered as a good practical range of values to determine the "average conditions" of different taxa: 18 to 34 CFU/plate for mesophilic environmental bacteria (25℃), and 14 to 28 CFU/plate for mesophilic human-source bacteria (37℃), 12 to 23 CFU/plate for mesophilic moulds. Thermophilic moulds (45℃), and thermophilic Actinomycetes (52℃) were rarely isolated.