Objective To investigate the sanitary conditions of central air conditioning and ventilation systems (CCVS) launched in different timeslots in underground railway stations in Shanghai, and provide scientific evidence for public health management.
Methods A total of 24 CCVS (8 sets launched before 2000, 7 sets between 2000 and 2010, and 9 sets between 2011 and 2017) in 12 underground stations of 9 subway lines in Shanghai were evaluated by field investigation and on-site test from July to September 2017 according to the Hygienic specification of central air conditioning ventilation system in public buildings (WS 394-2012). Sanitary evaluations included microorganisms and respirable particulate matters in air supply, microorganisms and dust load on the inner surface of air ducts, and Legionella pneumophila in samples of cooling water and condensate water.
Results The qualified rates of respirable particulate matters, total bacteria, and total fungi in air supply of the 24 sets of CCVS were 96.9%, 65.9%, and 65.2%, respectively. The qualified rate in fresh air was 10% only. The qualified rates of dust load, total bacteria, and total fungi on the surface of air ducts were 84.8%, 100.0%, and 100.0%, respectively. The qualified rate of Legionella pneumophila was 100.0% in condensed water and 95.8% in cooling water, respectively. The qualified rates of respirable particulate matters, total bacteria, and total fungi in air supply of CCVS activated before 2000 were 95.0%, 60.3%, and 75.0%, respectively; the qualified rates for CCVS activated between 2000 and 2010 were 100.0%, 83.3%, and 83.3%, respectively; the qualified rates for CCVS activated between 2011 and 2017 were 96.3%, 57.4%, and 42.6%, respectively.
Conclusion Better sanitary quality is found for the CCVS launched between 2000 and 2010, with higher qualified rates of microorganisms and respirable particulate matters in air supply, while relatively poor sanitary quality is found for the CCVS launched between 2010 and 2017. Strengthened management is required for the CCVS in Shanghai underground stations, especially on the woeful shortage of fresh air.
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