Field Study About Microbial Contamination In Air Supply And Return Systems Of Air-conditioning

The air supply and return systems of air-conditioning as one of the important channels, contacted outdoor and indoor environment and shoulder the important task to provide good air quality for personnel and equipment. However, in the practical engineering, because of the unreasonable design, operation and maintenance led to a large number of pathogenic bacteria and fungi, ventilation and air conditioning became one of indoor pollution sources. In recent years, great progress on the studies of pollution about air-conditioning systems at home and abroad have been made, but the microbial contamination in the air supply and return systems of air-conditioning haven't been the exact and standardize mechanism of theoretical. Due to the restrictions of the equipments, the microbial physiological characteristics of the majority only been did in the laboratory conditions. In order to study characteristic of microorganisms in the air-conditioning and ventilation systems, typical of the building ventilation and air conditioning systems was chose, microbes in air and dust was tested.The in-site testing and analyzing on microbiological tests of air supply and return systems of air-conditioning show that concentration of fungi was large than bacteria , and the environmental parameters as temperature, relative humidity and air velocity, relative humidity was the most obvious parameter affecting concentration of fungi. The concentration of microbes in air conditioning units are affected by the crowded people, so that the concentration of microbes was greatly improved. On the same environment conditions, dust deposition and microbial concentration had a proportional list. In this paper, the dominant fungi were identified as Penicillium, Aspergillus and Cladosporium, which are generally indoor microbial contamination, could trigger asthma and pneumonia and other diseases.Finally, this paper analyzed the effect of operation and maintenance rule of air conditioning on microbial contamination, and some proposal was gave on how to improve design, operation and maintenance of air conditiomng to reduce the ventilation Air-conditioning system of air microbial contamination.