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Objective @#To systematically evaluate the detection of Legionella pneumophila in central air-conditioning systems of public places in China, so as to provide insights into the management of L. pneumophila contamination.@*Methods@#The publications pertaining to L. pneumophila contamination in central air-conditioning systems of public places in China were searched in international and national databases, including CNKI, Wanfang Data, CBM, PubMed and Web of Science from January 1, 2010 to December 31, 2022. The publication quality was evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology. A meta-analysis was performed using the software Stata version 16.0. The pooled detection of L. pneumophila and its 95%CI were estimated. The publication bias was evaluated using Begg's test, and sensitivity analysis was performed with the leave-one-out evaluation for assessment of the robustness of the outcomes.@*Results@#A total of 742 publications were initially searched, and 29 publications were finally included, all of which were cross-sectional studies. The publications included 10 high-quality and 19 moderate-quality studies covering 6 160 samples, and the pooled detection of L. pneumophila was 17.20% (95%CI: 12.80%-21.90%). Subgroup analysis showed a higher detection rate of L. pneumophila in cooling water (21.80%) than in condensed water (5.50%) (P<0.01). According to the criteria defined in Hygienic Specification of Central Air-conditioning Ventilation System in Public Buildings (2006 version), the detection of L. pneumophila was 23.30%, which was higher than the detection (13.20%) according to the Hygienic Specification of Central Air-conditioning Ventilation System in Public Buildings (WS 394-2012) (P<0.05). The detection of L. pneumophila did not vary in place, region or sample (P>0.05). Begg's test showed no significant publication bias, and sensitivity analysis showed robustness of the results. @*Conclusions@#The detection of L. pneumophila ranges from 12.80% to 21.90% in central air-conditioning systems of public places in China. Health and environmental protection sectors need to improve the monitoring of L. pneumophila contamination in central air-conditioning systems of public places.
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Background The use of heating and ventilation air conditioning (HVAC) in public places is conducive to improving indoor air quality and increasing the users comfort level. However, HVAC may also become potential carriers of indoor airborne microbial contamination. Objective To understand the characteristics of microbial pollution and distribution of related pathogenic microorganisms in HVAC of star-rated hotels, and to provide a basis for effective control of such pollution. Methods According to the requirements of the Hygienic specification of central air conditioning ventilation system in public buildings (WS 394-2012), two sets of HVAC in two star-rated hotels (A and B, inaugurated in 2002 and 1998, respectively) in the central area of Shanghai were randomly selected on September 9, 2020 for the hygienic evaluation of microorganisms in the air supply and respirable particulate matter (PM10) in the air supply, dust accumulation and microorganisms on the inner surface of the ducts, as well as Legionella pneumophila in cooling water and condensate water. At the same time, 3 samples from the inner surface of ducts, 1 sample from the surface of the filter, 1 sample from the condensate, and 1 sample from the cooling water were collected from each set of HVAC, a total of 12 sample from 2 sets of HVAC, for Illumina HiSeq metagenomic sequencing，and the samples are divided into 3 groups according to their types: duct group, filter group, and water sample group. The α-diversity indices (Shannon index, Simpson index, Chao1 index, ACE index, and goods_coverage index) were calculated to reflect the microbial community composition; and the β-diversity of the three groups were studied by principal component analysis to determine the similarity of the microbial communities. Results The maximum total number of bacteria and fungi in the air supply of the HVAC were 1158 CFU·m−3 and 344 CFU·m−3 for Hotel A respectively; and 2000 CFU·m−3 and 532 CFU·m−3 for Botel B respectively. β-hemolytic streptococci were negative in all samples; the respirable particulate matter, microorganisms and dust accumulation on the inner surface of air ducts, Legionella pneumophila IN cooling water and condensate samples all met the standards. The results of Illumina HiSeq sequencing showed that a total of 17322 microorganisms were reported in the 12 samples, with bacterial microbiota accounting for 97.31% of the classified genes and the remaining 2.69% were from fungi, viruses, and parasites. At the species level, Staphylococcus epidermidis, Pseudomonas, Alternaria, and Malassezia were the dominant microbial taxa measured in this survey. The results of α-diversity analysis showed that the values of Shannon index, Simpson index, and Chao1 index for the three groups of samples were duct > filter > water sample. The goods coverage indices of all sample groups s were close to 1. The principal component analysis showed that the contributions of two principal components were 19.27% and 14.25%, respectively, in which the samples of the filter and duct groups were better clustered into one category. Conclusion The overall hygiene conditions of the two hotels are good, except for the serious microbial contamination in the air supply of HVAC. Metagenomic sequencing reveals complex microbial communities of HVAC, including bacteria, fungi, viruses, and parasites. The species composition vary by sample groups, particularly the species compositions of the samples from filters and ducts are close and dominated by pathogenic microorganisms of human origin, suggesting that the potential biosafety hazards of HVAC should not be ignored.
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Objective:To investigate the hygienic condition and maintenance management of air conditioners in observation hotels， and give suggestions on reducing the risk of COVID-19 transmission from the daily use. Methods:This study selected 11 observation hotels chosen by government and 3 observation hotels chosen by large companies in Minhang District. The types and sanitary conditions of the air conditioning system were revealed through the daily supervision. Hotel staffs’ knowledge of air conditioning system and their mastery of how to use and maintain air conditioning system were surveyed through questionnaire. Results:Survey of air conditioning types showed that in 14 hotels， 12 were distributed air conditioning systems and 2 were semi-centralized air conditioning systems （including fresh air systems）. The investigation found that there was dust accumulation in the fresh air ducts in one hotel guest room， dust accumulation in the filter screen of fresh air intake in one hotel， and the sanitary problem of condensate water （without centralized discharge） in two hotels. All of 14 hotels had daily cleaning and disinfection records， but they were not perfect. The hotel health management personnel’ awareness rate of air conditioning was low， although they had a positive attitude towards the cleaning and disinfection of the air conditioning system. They could do the active entrusted testing， cleaning and disinfection of the air conditioning systems. Conclusion:The air conditioning systems of some hotels have hygiene problems， and hotel health management personnel are lack of knowledge of standard operation and maintenance of air conditioning systems. The air conditioning systems of observation hotel should be cleaned and disinfected before use. At the same time， it is necessary to strengthen the training of hotel health management personnel on the use and maintenance of air conditioning systems. So the transmission of the COVID-19 through air conditioning systems can be effectively prevented.
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Objective: The construct a pharmacy intravenous admixture service (PIVAS) for changing configuration of intravenous drugs from decentralized configuration to centralized allocation supply so as to guarantee the safety of clinical drugs of hospital. Methods: Through constructed PIVAS, adopted purified air-condition system and established fluid-layers room of different grade to achieve sterile environment for configuration of intravenous drugs. And the centralized allocation should be implemented as the characteristics of different drugs. Results: The PIVAS could reduce the waste of drugs and decrease their cost. At the same time, it guaranteed the safety of clinical medication of hospital on the bases of enhancing work efficiency of clinical nurse and reasonably resolving allocation of human resources. Conclusion: The PIVAS that changes the configuration of intravenous drugs from decentralized configuration to centralized allocation supply can positively and effectively promote the safety of clinical medication and increase work efficiency of nursing and care.
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OBJECTIVE:To improve the system of management and maintenance for the purification air-conditioning system in PIVAS,and to further strengthen the management of cleaning environment. METHODS:The cleanness monitoring project of purifi-cation air-conditioning system in PIVAS of our hospital was introduced in terms of temperature and humidity record,pressure differ-ence record,airborne particles detection,settling microbe monitoring report. And the monitoring results were analyzed. RESULTS:The temperature and humidity,pressure difference of clean area in PIVAS of our hospital are both in line with the standard of Phar-macy Intravenous Admixture Quality Management Specification (2010 edition),i.e. temperature at 18-26 ℃,relative humidity of 40%-65%;negative pressure difference between antibiotics,hazardous drug dispensing area and second dressing room are 5-10 Pa. The number of airborne particles (average static particle/m3) at various cleanness degrees in clean area are all in line with the standard of GMP(2010 edition),i.e. maximal allowable number of airborne particles(≥0.5 μm)were 3 520/m3(100 degree);352 000/m3 (10 000 degree);3 520 000/m3 (100 000 degree). The percentage of qualified static settling microbe detection reach 100%in clean area,which is in line with the standard of Settling Microbe Detection Method in Clean Room(Area) of Pharmaceu-tical Industry,i.e. criteria for settling microbe(90 mm)CFU/0.5 h≤1(100 degree);≤3(10 000 degree);≤10(100 000 degree). The percentage of qualified dynamic settling microbe detection is in low level,especially those of dispensing room and secondary dressing room only reaches 80%. CONCLUSIONS:It’s important for effective hospital infection control in PIVAS,the quality im-provement of intravenous injection,the safety guarantee of drug use in patients to further improve standard operation procedure of purification air-conditioning system management and maintenance,and manage and maintain the purification air-conditioning sys-tem completely and scientifically.
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Objective A correlation method for evaluating operation quality of air conditioning systems is proposed , based on the outdoor and the indoor temperature history data of the terminal user from internet of things for the central air conditioning system , for lacking efficient way to evaluate . Methods A methematical model is set up based on the variance ratio of the data of the indoor and out temperture obtained from IOT within a given time interval , and theoretically induce the possibility and correctness to employ these index to evaluate the operation quality of the central air conditioning system . Results A typical central air conditioning system of a large sacal hospital is analyzed , the results shows the variance ratio of the indoor and outdoor temperature can reflect the capacity of the central air conditioning system for controlling the indoor temperature . Conclusion The method proposed for evaluating the op-eration quality of the air conditioning system based on IOT system is theotically correct and practically efficient , and can be employed to evaluate the operation quality of the air conditioning system of large scale medical buildings .
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Objective To konw the Legionella contamination in the central air condition system and secondary water supply system in the public places of Jiangxi province. Methods 145 water samples were collected from the public places with central air conditioning system and secondary water supply system, in July to September in 2005-2006. Bacteria culture, hemagglutination test and duplex PCR test were used to identify Legionella. Results 15 Legionella strains was isolated from 145 samples, the positive rate was 10.34%, 7 Legionella strains was isolated from 78 samples of central air conditioning system, the positive rate was 8.97%, 8 Legionella strains was isolated from 57 samples of secondary water supply system,the positive rate was 14.04%. Conclusion It is necessary to strengthen the surveillance of Legionella in central air conditioning system and secondary water supply system.
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Objective To verify the flow field performance of the air dynamic wind tunnel. Methods The performance of the flow field was evaluated by testing the flow speed of sample-point on the sample-transect of the tunnel. Results Among the flow range of the tunnel, the relative deviations of the speeds of each sample-point on the sample-transect were less than 10%. When the flow rate was set, the relative deviations of the sample-transect average speed in different test period were less than 10%. The ratio of average wind velocity of upper reach to down reach of the tunnel was between 0.92 and 1.03. Conclusion The flow field of the air dynamic wind tunnel is even, stable and coincident.
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Objective To explore the transmission route of Legionella pneumophila in central air-conditioning system. Methods The environmental samples collected from four public places of Nanjing city were detected by nested-PCR and analyzed by phylogenetic analysis. Results The positive rate of Legionella pneumophila in sediment, cooling water, aerosol near cooling tower, dust in duct surface and indoor air were 100%(9/9),78.6% (11/14),25.4% (17/67),16.7% (2/12) and 17.3% (13/75), respectively. The nucleotide sequence similarities of Legionella pneumophila in cooling water and indoor air was more than 92%. Conclusion The main pollution source of Legionella pneumophila is cooling water and Legionella pneumophila can be transmitted to indoor air through central airconditioning system.
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Objective To know the hygienic administration status of central air conditioning system(CACS)and the Legionella contamination of cooling water in public places; and to identify the risk factors for legionella contamination associated with hygienic administration measures of CACS. Methods One hundred and forty-eight public places with CACS were recruited and the hygienic administration status was investigated by questionnaire survey in Sep. 2008. The culture methods were used to identify Legionella in cooling water. Results Positive rate of Legionella pneumophila in cooling water was 68.1%, 65.1% and 66.7% respectively in the condition of disinfection, preservative (detergent) and regular examination of the cooling water. The positive rate of Legionella pneumophila in cooling water was 92%, 87.7% and 84.7% respectively without disinfection, preservative,detergent and regular examination of the cooling water. Conclusion Disinfection, preservative,detergent and regular examination of the cooling water can reduce Legionella contamination risk.
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Objective In order to investigate and evaluate the heating-ventilating-air conditioning (HVAC) systems in the public areas and therefore provide the support for the hygiene management. Methods According to Hygiene Criterion of HVAC System, 10 HVAC systems in 10 star grade hotels in Nanchang were selected and PM10 and the total count of aerobic bacterial in the air condition systems, the collected dust weight and the total count of aerobic bacterial in the dust in the inner surface of ventilation vessels, the legionella bacteria in cooling tower water were determined. Results The HVAC systems in the 10 hotels, 90.1% for the PM10 and 73.3% for the total count of aerobic bacterial in the air condition systems, 8.9% for the collected dust weight and 86.7% for the total count of aerobic bacterial in the dust in the inner surface of ventilation vessels were over the standard limits, the legionella bacteria were detected in two of the investigated HVAC systems cooling tower water. Conclusion The hygienic problems are existed in the ventilated systems in the air conditioners in the pubic places.The health supervision and monitoring must go on enhancing.
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Objective To investigate the pollution status of heating-ventilating-air conditioning(HVAC) systems in Shenyang public place. Methods The dust samples were collected and examined from the HVAC system in twelve hotels and ten shopping malls in Shenyang in March-June, 2004. Results Among HVAC systems in Shenyang public buildings, 71.51% of them were moderately polluted and 27.37% were seriously polluted. The rate of serious pollution of hotels was higher than that of shopping malls, the volume of dust in the air pipes in hotels was lager, but the amount of bacteria and fungi was less than that of shopping malls. Conclusion The HVAC systems of Shenyang public buildings have been seriously polluted.
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Objective To investigate the actual pollution status of heating-ventilating-air conditioning(HVAC) systems in five-star grade hotels in Beijing. Methods Seven sets of centralized HVAC system from five five-star grade hotels in Beijing were selected for sampling monitoring and videotaping in situ from August 2003 to October 2003. Results There were six sets HVAC systems seriously polluted and one set was in moderately polluted according collected dust weight. The total counts of bacteria in the dust were in medium pollution grade in four sets of HVAC systems; The total quantity of fungus in the dust were in medium pollution grade in five sets of HVAC systems; The video materials showed that inside the air duct there were fungus, construction rubbish and deposit of large quantity of dust. Conclusion The HVAC systems of those five hotels were seriously polluted.
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Objective To explore and describe the sampling methods for aerosol from cooling towers in the centralized air conditioning system, early-warning indicators, the effect factor and present status of contamination by Legionella.Methods Air-conditioning systems were sampled two rounds in 13 guesthouses, markest and bathing spots of Maanshan City in June-August, 2008.Aerosols were collected by fluid-striking microbial aerosol sample collector, while water samples from cooling tower and swelling box were obtained.Legionella were determined respectively for 67 samples by germiculture and polymerase chain reaction.Results The positive rate of Legionella in aerosols by germiculture was 0, meanwhile it was 50.0% by polymerase chain reaction for Legionella pneumophila.The positive rate in aerosols was 90.0% as the air-sampling volume exceeded 400 L.The positive rate of aerosols increased while the operating-time of cooling tower increased.The relative humidity in Legionella positive groups was higher than that in Legionella negative groups.Conclusion The positive result for Legionella pneumophila by polymerase chain reaction should be an important indicator for early-warning for the occurrence and spreading of Legionnaires' disease.The air-sampling volume of over 400 L is available by sampling collector for the detection of Legionella pneumophila by polymerase chain reaction.Risk of Legionella contamination in aerosol would be raised in high-humidity environment.
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Objective To understand the sanitary status of the air conditioning system of public places and to discuss the countermeasure.Methods Fifty public places where the air conditioning system were used were selected as the research objects in September 2008.The questionnaires about the hygienic management, the air conditioning system and the cooling tower were used to investigate the basic situations of the air conditioning system in public places,and Legionella pneumophila(Lp) of cooling water in the cooling tower was detected.Results All the fifty public places didn't establish complete sanitary management system.90% of the cooling towers were less than one kilometer from the residential areas, schools, kindergartens, agedness flats and hospitals.And 18% of the cooling towers were less than one hundred meters from the walking streets and entertainment plaza.Moreover,8% of the public places had not fresh air, the air purification wasn't installed in 74% of the public places and sterilization equipments, and automatic or on-line sterilization equipments in the cooling towers weren't installed in all the public places.In addition, the positive rate of Legionella pneumophila in the cooling towers was 89.58%.Thereinto, the positive rate of Lp1 type(79.07%) of Legionella pneumophila was significantly higher than that of Lp2-Lp14 type(11.63%) as well as that of Lp1 type and Lp2-Lp14 type(9.30%)(P0.05).Conclusion The air conditioning systems of public places are being faced with some sanitary problems and the cooling water in the cooling tower was polluted with Legionella pneumophila.Therefore,it is suggested that its sanitary management should be reinforced and the sterilization management of cooling water as well as the shield between the cooling towers and the circumferences should be taken into account.
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Objective To know the contamination situation of the centralized air conditioning-ventilating systems in hotels in Shenzhen City, Guangzhou province and to ensure the indoor air quality when the centralized air conditioning-ventilating systems were at working. Methods 22 hotels were selected to determine the total count of bacteria and fungi in internal surface of pipes and air blow, the dust volume of internal surfaces of pipes, inhalable particulate matter(PM10) in air blow, and Legionellae in cooling tower water. Results The eligibility percent of dust volume, the total number of bacteria and fungi in internal surface was 94.76 %, 95.71% and 91.90 % respectively,the eligibility percent of PM10, the total count of bacteria and fungi in air blow was 42.54%, 94.76% and 84.29% respectively, and the detected rate of Legionellae was 57.50%. Conclusion The pollution in some degrees has been observed in the centralized air conditioning-ventilating systems in hotels of Shenzhen City, so it is considered as the important measure to improve indoor air quality and ensure people health to strengthen management of centralized air conditioning-ventilating systems in the usage.
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This article introduces the performance, merits and shortcomings of several air conditioning systems employed in HBO chamber. The improvement methods of this system are also recommended.