Comparison of Legionella Contamination of Cooling Water System and Freezing Water System in Central Air Conditioning System / 环境与健康杂志

ABSTRACT

Objective To compare the Legionella contaminative status of the cooling water system with freezing water system in central air conditioning system. Methods Legionella was tested in water and samples of all components from the cooling tower, condenser, swelling water box and evaporator of central air conditioning among 26 public places. Results The total detected rate of Legionella was 64.0% among 100 samples from two kinds of water system, 71 strains of Pneumophila legionella were separated. The detected rates were 75.0% and 52.1% in the cooling water systems and freezing water systems respectively. The amount of Legionella was more than 100 per milliliter in the cooling water systems. The detection rate of cooling tower water and swelling water box water was 100% in the air conditioning system run for over 10 years and 5-10 years. Concordance rate of consequence was 50.0% in cooling tower water and condenser water of the cooling water systems, the rate was 55.0% in swelling water box water and evaporator water of the freezing water systems. Conclusion This study suggested that more attention should be paid to the contaminative status of Legionella in freezing water system of central air conditioning system. Cooling tower and swelling water box should be the key parts in cleaning and disinfection of air conditioning system.