AIR-CONDITIONING AND MICROBIOLOGICAL ENVIRONMENT IN THE LECTURE ROOM

The influence of air-conditioning system and equipment on the indoor environmental conditions inside the lecture room of the Czech University of Life Sciences Prague is described. The microbial contamination (filamentous fungi and bacteria) and also the main microclimatic parameters of the air, temperature and relative humidity of air, were measured and evaluated in relation to different performance conditions of the lecture room. Predominant bacteria detected were Gram-positive cocci, Micrococcus spp., Staphylococcus spp., and endospore-forming bacilli (Bacillus spp., Bacillus mycoides). The intensity of air-conditioning influenced the quality of indoor environment in the room. 15 min after starting the air-conditioning the number of airborne bacteria in the lecture room decreased to 35–40 and later on to 20. Conidia of microscopic filamentous fungi were passing through the filters for outdoor air filtering (non-woven polyester fabrics Firon Special G 460 for coarse dust, class filtration G 3). Allergenic Cladosporium was dominant and after starting the air conditioning its occurrence in the room increased, no matter if the filters were clean or dusty. The highest values of 555 CFU.m-3 were measured in summer after 5 h of air conditioning. Contamination by allergenic Aspergillus increased sixteen times after 15 min of air-conditioning performance with dusty air filters.