Actual Measurement and Analysis on Microbial Contamination in Central Air Conditioning System at a Venue in Dalian, China

Actual measurement and analysis were carried out on microbial contamination in central air conditioning system at a venue in Dalian. By studying the microbial contamination in two air handling units with different thermal environments, we found that the fungi and bacteria were common existing on the surface of filter, and the trend of cell density distribution was center > against the wall > corner; The microbial pollution associated in the dust and floating in the air was extremely serious. By comparing the two units, we observed that fungus concentration: Unit A > Unit B, and bacteria concentration: Unit A < Unit B,. And the candida spp. accounted for 80 percent of the sample in Unit A; while in Unit B the cladosporium spp. occupied up to 50%. At the end of the paper, according to the results of measurement and analysis, the methods of controlling microbial contamination in HVAC system have been proposed.