Abstract: ObjectiveTo know the current situation of air quality in public places of Zhoushan city,the running and cleaning of the central air conditioning ventilation systems,and the status of Legionella bacteria contamination,in order to improve indoor air quality in public places.Methods22 units with central air conditioning ventilation system were investigated.The content of CO,CO₂,PM₁₀,the volume of outdoor air and the total number of bacteria in public places with ventilation systems of central air conditioning,the content of the dust and the total number of fungi,bacteria,β-hemolytic streptococcus in ventilation pipes,the total number of bacteria and fungi in wind sending outlet,as well as condensed water and Legionella pneumophila of cooling water were tested and evaluated.ResultsThe pass rate of the total number of bacteria and fungi in sending outlet were 37.50%,46.88% respectively.The pass rate of the total number of bacteria and fungi in ventilation pipes were 65.63%,81.25% respectively.Pipelines dust pass rate was 81.25%.Qualified fresh air was 62.50%.Carbon dioxide was 81.25%.Carbon monoxide,PM₁₀ and bacteria in the air were 100.00%.Hemolytic streptococcus was not detected while the detection rate of Legionella bacteria was 35.71%.ConclusionIn Zhoushan city,the ventilation system of central air conditioning has an impact on indoor air quality,as well as human health.To improve indoor air quality,we must strengthen the management of ventilation systems of air conditioning,clean and disinfect ventilation systems of air conditioning regularly.Thus,the transmission of respiratory diseases can be blocked,people's health in public places can be protected.