Hygienic Investigation on the Central Air Conditioning and Ventilation System of New Public Places in Wuxi City

Objective To explore the hygienic status of central air conditioning and ventilation systems in new public places of Wuxi.

Method Based on the Hygienic standard and hygienic evaluation standard for central air conditioning and ventilation system in public places(WS/T 395-2012), 26 new public places in Wuxi were investigated in 2014—2015, including field investigation and hygienic examination.

Results Different types of air conditioning and ventilation systems were used in different functional zones. Hybrid air conditioning system, a full air mode, was used in large space; while fresh air unit and fan coil (or return box unit), an air-water mode, was used in small space. New air primary efficiency filter, return air filter and air inlet protection network were fitted in 100% (26/26) of places. Fresh air was all taken directly from outdoors. The position of new air port was set on the side wall > roof > fresh air shaft. Air-cooled heat pump was used as cold and heat source in 34.6% (9/26) of places; centrifugal/screw chiller was used as cold source and heat exchange/steam boiler was used as heat source in 65.4% (17/26) of places. The hygienic systems were not complete and lack of regular cleaning and disinfection program and contingency plan for the air conditioning and ventilation system. The mean qualified rate in the initial inspection was 46.2% in 26 public places. Unqualified indicators were total bacterial count and the total number of fungi on the inner surface of air ducts, PM₁₀ and the total number of bacteria and fungi of air outlet. The qualified rates were 100% after effective cleaning and disinfection.

Conclusions The design of centralized air conditioning and ventilation system in new public places was basically meeting the requirement, but the hygienic system needs to be improved. The hygienic indicators could not meet the requirement of the standard in over half of central air-conditioning systems in this study. It was recommended that to clean and disinfect the centralized air conditioning system before officially opening new public places.