Sanitary Condition of Central Air Conditioning Ventilation Systems in Public Places of Luohu District, Shenzhen (2014-2018)

Objectives To investigate and analyze the hygienic condition of central air conditioning ventilation systems in public places in Luohu District, Shenzhen from 2014 to 2018, and provide vidence for health supervision and management.

Methods A total of 190 public places in Luohu District, Shenzhen, were selected in 2014-2018. The hygienic indicators include total fungi count, total number of colonies, and dust on inner surface of air duct, total fungi count, total number of colony, β-hemolytic streptococcus, and inhalable particulate matter in air supply, fresh air volume, and Legionella Pneumophila in cooling water and condensate water.

Results Total 190 air conditioning systems were selected in 2018, the qualified rate of the public places was 74.21%, and the qualified rate of samples was 88.42%. The qualified rate of ten hygienic indexes ranged from 62.96% to 100.00%. The qualified rate of the total number of colonies in the air supply system was lower than that on the inner surface of the duct (P < 0.05), and the qualified rate of the total fungi in the air supply system was lower than that on the inner surface of the duct (P < 0.05). The total number of colonies was positively correlated with the total fungi on the inner surface of the duct (P < 0.05), which colonies was also positively correlated with the total fungi in the air supply (P < 0.05). Total 258 cooling water samples were collected, Legionella Pneumophila was detected in 13 cooling water samples with a detection rate of 5.04%, and LP1 type was the main type of detected Legionella Pneumophila, accounting for 61.54%.

Conclusions There is still room for improvement of the sanitary status of central air conditioning ventilation systems in public places in Luohu District, Shenzhen City. Relevant departments should strengthen supervision and education work.