Objective To understand the hygienic status and contamination characteristics of central air conditioning ventilation systems before commencement of commercial operation in public places of Shanghai.
Methods The hygienic indices of 62 selected central air conditioning ventilation systems were detected according to the Hygiene Specification for Central Air Conditioning Ventilation System in Public Buildings.
Result The qualified rates of PM10, total bacteria, total fungi, and β-hemolytic streptococcus bacteremia in the supply air samples were 95.2%, 87.1%, 85.5%, and 100.0%, respectively. The qualified rates of accumulated dust mass, total bacteria, and total fungi on the internal surface of ventilation ducts were 90.3%, 90.3%, and 91.9%, respectively. Legionella pneumophila was not detected in the condensed water samples, but 61.5% of the cooling water samples were positive for Legionella pneumophila and the main type was Lp1. There were correlation variations and seasonal changes among hygienic indices of central air conditioning systems.
Conclusion Hygienic issues exist in some newly installed public central air conditioning ventilation systems before commercial operation. More efforts should be directed toward future studies on the inter-index correlations to optimize evaluation index systems. Given the seasonal changes, strengthened health supervision in summer and winter would be more appropriate.
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