Objective To analyze the potential risk factors of hygienic situation of centralized air ventilation system in public venues in Luwan District of Shanghai, to explore the key elements for effective management, and to provide scientific basis for airborne disease prevention.
Methods A total of 30 public venues were chosen by stratified sampling for a questionnaire survey. Assessments were carried out under Hygienic standard for centralized air conditioning ventilation system in public places and Hygienic assessment criterion of cleaning and disinfection of centralized air conditioning ventilation systems in public places.
Results The selected public venues did not make health emergency plans nor provid regular hygienic evaluation reports. The survey found that 70.0% fresh air inlets were close to pollution sources, only 6.7% places installed air purification and disinfection devices, and none of them were equipped with cooling tower demisting to control aerosols. The cooling water test showed that the positive rate of Legionella pneumophila was 70.0% and the common type was Lp1. The average conductivity of the positive water samples was (5 897.55& #177;601.16) μs/cm and that of the negative was (9 031.12& #177;1 172.35) μs/cm (t=-2.571, P<0.05).
Conclusion Indicators such as conductivity could be considered to identify Legionella pneumophila in cooling water for prewarning of pollution. The management essentials of centralized air conditioning ventilation systems in public venues are the control of fresh air pollution and aerosol spread, as well as regular cleaning work and evaluation.
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