Study On The Hygienic Condition And Influencing Factors Of Centralized Airconditioning Ventilating System In The Hospitals Of Hunan Proyince

[Objective] The aim of this study was to investigate the hygienic status of centralized airconditioning ventilating systems (CAVS) in the hospitals of Hunan Province, to analyze its influencing factors, and to assess the effects of health intervention, so as to provide scientific data and decision-making basis for the health management of CAVS in the hospitals of Hunan Province.[Methods]69CAVS in hospitals of Hunan Province were selected by random sampling. Air from the air supply outlets was collected for8indices like total bacterial count detection in accordance with the Sanitation Criterion of the Center Condition in Public Places.25out of69CAVS were randomly sampled for health intervention. The intervention effects were studied. The over standard rates and detection rates were compared by chi-square test.[Results]①The hygienic status of CAVS:The investigation of69CAVS from40hospitals from2008to2010indicated that35CAVS were qualified for all detection indices. The overall qualified rate was50.72%. The qualified rates for the total bacterial count, total fungi count and β-haemolytic streptococci of the air from air supply outelets were80.6%,74.7%and100%respectively. The qualified rates for the deposit dust amount, total bacterial count and total fungi count of the deposit dust collected from the ventilating duct sections were91.9%,97.6%and97.2%respectively.②The influencing factors of CAVS contamination:Cleaning produced significant effects on the total bacterial count, total fungi count of air collected from the air supply outlets and on the deposit dust amount collected from the ventilating duct sections and legionella pneumophila from cooling water (P<0.05). From2008to2010, the CAVS cleaning rates were20.59%,52.17%,77.77%, and the total qualified rates were17.65%,78.26%,91.67%respectively, indicating a step-wise increase tendency. Hospital grade significantly affected the over standard rate for total bacterial count(X2=5.55, P=0.018)and the detection rate for total fungi count (Z=2.045, P=0.041) of air from the air supply outlets. Seasons significantly affected the over standard rates for total bacterial count and total fungi count of air from the air supply outlets (X2=13.98, P=0.003, X2=19.95, P=0.000).③Health evaluation of results of intervention measures:Before and after the intervention,25sets of the CAVS results showed that,4exceeded the highest rates of detection indicators like air outlet air bacteria and fungi, wind pipe of dust amount and cooling water of Legionella pneumophila exceeding the rate difference, with statistical significance (χ2=19.156, P=0.000; χ2=35.842, P=0.000;χ2=7.228, P=0.000;χ2=15.789, P=0.000), the first three quantitative indexes in the difference, with statistical significance (Z=3.551, P=0.000; Z=4.654, P=0.000; Z=6.502, P=0.000)[Conclusions] The air from the air supply outlets of CAVS in Hunan Province was heavily contaminated. The deposit dust in the ventilating ducts was slightly contaminated. The cooling water was heavily contaminated by legionella pneumophila while the condensate water was not. The detection rates for different serotypes of legionella pneumophila indicated no significant difference. The main influencing factor of contamination of CAVS were cleaning. Hospital grade and season only affected the detection rate for total bacterial countand total fungi count of air from the air supply outlets. Intervention measures like regular cleaning, increase of ventilation, choice of effective environmental protection disinfectant, and regular training, can effectively reduce the pollution of CAVS.