Sanitation of central air conditioning ventilation systems in public places in Suzhou, China, 2020—2021

Objective To investigate the sanitation of central air conditioning ventilation systems in public places in Suzhou.

Methods From July to August, 2020 to August to September. 2021, 38 central air conditioning ventilation systems in normal use in the urban area of Suzhou were monitored by random sampling. PM₁₀, total bacterial count, total fungi count, β-hemolytic streptococcus in supply air, total bacteria count, total fungi count, dust accumulation on the inner surface of the air duct, and legionella pneumophila in cooling water were detected. Sampling and testing were conducted according to the Hygienic Specification of Central Air Conditioning Ventilation System in Public Buildings(WS 394-2012)and the Examination Method for Public Places(GB/T 18204.5-2013).

Results Among the 38 central air conditioning ventilation systems tested from 2020 to 2021, the overall qualified rate of indicators was 93.8%, with the highest qualified rate in hotels, the lowest qualified rate in medical places (χ²=11.87, P < 0.05). The qualified rates of PM₁₀, total bacteria count, total fungi count, and β-hemolytic streptococcus in air supply were 97.8%, 92.4%, 76.1%, and 100.0%, respectively, with statistically significant differences among indicators (χ²=41.81, P < 0.05). The qualified rates of total bacteria count, total fungi count and dust accumulation on the inner surface of the air duct were 98.4%, 89.5%, and 100.0%, respectively, with statistically significant differences among indicators (χ²=20.42, P < 0.05). The detection rate of Legionella pneumophila in cooling water was 10.5%.

Conclusion The sanitation of central air conditioning ventilation systems in public places in Suzhou is generally good, but attention needs to be paid to fungal and legionella pollution.