Objectives To understand the hygienic quality of central air conditioning ventilation systems at public places in Zhongshan, and to provide scientific basis for improving their hygienic quality.

Methods Central air conditioning ventilation systems at 65 public places in Zhongshan city were randomly selected in May to November in 2013; samples were collected from 5 air vents and 5 internal surface of ventilation pipes of each system, and one or two cooling water or condensate water samples of each system were determined.

Results The qualified rates for central air conditioning ventilation system at public places in Zhongshan city was 53.85%. The qualified rates for PM₁₀, counts of total bacteria, fungi and β-hemolytic streptococcus were 100%, 96.70%, 94.73% and 100% respectively. The qualified rates for dusts, bacteria counts and total fungi counts on the internal surface of air pipes were 100%, 95.60% and 93.41%, respectively. the qualified rates for cooling water and condensate water were 80.90% and 97.62% respectively.

Conclusions The hygienic quality of central air conditioning ventilation system at public places in Zhongshan city was not optimistic. There were some potential problems on the contamination of microorganism, mainly the total bacteria count, fungi count and legionella pneumophila.