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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:To evaluate the implementation effect of the "Shanghai Construction Project Centralized Air Conditioning and Ventilation System Hygiene Evaluation Specification （Trial）" （hereinafter referred to as the "standard"）. Methods:The "Centralized Air Conditioning and Ventilation System Hygiene Evaluation Report Score Sheet" was used to compare the quality of air conditioning hygienic evaluation reports before and after the implementation of the standard. Results:After the implementation of the standard， the total score of the air conditioning health evaluation report was significantly higher than that before the implementation （t=3.164， P=0.002）. The scores of format， general theory， engineering analysis and suggested conclusion after the implementation were all higher than before the implementation （t=3.701， 2.012， 2.152， 2.450， respectively， all P<0.05）. The difference in scores of evaluation process was not statistically significant between before and after the standard implementation （P=0.465）. Conclusion:After the implementation of the standard， the quality of air-conditioning health evaluation reports has significantly improved.
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Objective To investigate the hygienic status of ventilation systems in centralized air-conditioning in Nanshan district of Shenzhen City, and to provide a basis for standardizing hygienic management and targeted prevention and control. Methods According to the requirements of "Hygienic Specifications for Central Air Conditioning and Ventilation Systems in Public Places" WS 394-2012, 303 public places using central air conditioning and ventilation devices in Nanshan District of Shenzhen City were sampled from 2016 to 2019 for four consecutive years. From these, 19 large public places were randomly selected for investigation of the hygienic condition of the air supply system. Results The qualified rates of central air conditioning ventilation systems from 2016-2019 were 94.56%, 96.96%, 98.33% and 95.65%, respectively, and there was no statistically significant difference among them (P>0.05). The qualified rates of accumulated dust, total bacterium and fungus counts on the inner surface of the ducts were 100%, 98.34% and 98.67%, respectively. PM10, total bacterium counts and fungus counts in the supplied air of the randomly selected 19 large public places were 100%, 63.15% and 78.94% respectively. The overall detection rate of Legionella pneumophila was 12.21%, and the detection rate of cooling water was larger than that of condensed water (P0.05). Conclusion The sanitary condition of the central air conditioning ventilation system in the public places of Nanshan district needed to be improved. Legionella pneumophila was still detected in some public places. Daily cleaning and disinfection management of central air condition systems should be strengthened.
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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 design a controller for the air environment of cabins of special vehicles .Methods The microprocessor was used to collect and store parameters ,and calculate automatically the operative mode of actuators ,such as the fan,air-conditioner,oxygenerator,air cleaner, filtering and boosting devices according to the preset target values .Output commands by RS485 were used to control actuators .Results and Conclusion The controller is capable of control integration for air-adjusting equipment while improving the control effect of the air quality in cabins of special vehicles .
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La adquisición efectiva de tecnologías en salud está enfocada al mejoramiento de la calidad y eficiencia, en la prestación de los servicios de salud ya que es un proceso complejo. Dentro de este proceso se destacan la evaluación técnica y clínica. El objetivo de la evaluación de tecnologías en salud es recolectar, analizar y sintetizar información y conocimiento para contribuir a mejorar la toma de decisiones en la práctica médica y en las políticas de salud. En este trabajo se presenta una evaluación en procesos de adquisición de sistemas de aire acondicionado en servicios de salud, basada en la definición de variables en campos de evaluación; dichas variables cuantifican lo técnico y funcional del equipo en su entorno clínico y económico. De igual manera, se pretende impulsar en los departamentos de ingeniería clínica la implementación de metodologías de amplia aceptación y efectividad que tienen como objetivo primordial la adquisición de tecnologías en salud basados en la evidencia.
The effective acquisition of health technologies is focused on improving the quality and efficiency in the provision of health services as it is a complex process. Within this process the technical and clinical evaluation are highlighted. The objective of the health technology assessment is to collect, analyze, and synthesize information and knowledge to help improve decisionmaking in medical practice and health policy. This paper presents an evaluation process of acquiring air conditioning systems in health care facilities, based on the definition of variables into a field evaluation; these variables quantify the technical and functional team in their clinical and economic environment. Similarly, it is intended to promote in clinical engineering departments, the implementation of widely accepted methodologies and effectiveness that have, as its primary objective, the acquisition of technologies in evidence-based health.
A aquisição efetiva das tecnologias da saúde é focada na melhoria da qualidade e eficiência na prestação de serviços de saúde, pois é um processo complexo. Dentro deste processo se destaca a avaliação técnica e clínica. O objetivo da avaliação de tecnologias em saúde é coletar, analisar e sintetizar informações e conhecimentos para ajudar a melhorar a tomada de decisão na prática médica e a política de saúde. Neste trabalho se apresenta um processo de avaliação de aquisição de sistemas de ar condicionado nos serviços de saúde, com base na definição de variáveis no campo da avaliação; essas variáveis vão quantificar o técnico e o funcional do equipamento em seu ambiente clínico e econômico. Da mesma forma, pretende-se promover nos departamentos clínicos de engenharia a aplicação de metodologias amplamente aceitas e eficácia que têm como objetivo principal a aquisição de tecnologias em saúde baseada em evidências.
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Air Conditioning , Bacterial Proteins/genetics , DNA-Directed RNA Polymerases/genetics , Francisella , Flavoproteins/genetics , Water Microbiology , Base Sequence , China , DNA, Bacterial/genetics , DNA, Ribosomal/genetics , Francisella/classification , Francisella/genetics , Francisella/isolation & purification , Molecular Sequence Data , Molecular Typing , Phylogeny , /genetics , Sequence Analysis, DNAABSTRACT
Objective To assess the hygienic status of the central air conditioning ventilation system in public places by fuzzy comprehensive evaluation method.Methods According to the comprehensive evaluation method of public place (WS /T 199—2001),a fuzzy comprehensive evaluation method was applied to evaluate central air conditioning ventilation systems in 15 large public places of Jinhua City.Results The qualified rate of central air ventilation system was 53.30%, and the qualified rates of total number of bacteria,the fungi,β-hemolytic streptococcus in air blow and Legionella bacteria in the cooling water all reached 100.00%.At the same time,the qualified rate of bacteria,fungi and dust volume in internal surface of pipe were 93.33%,86.67% and 80.00% respectively.The qualified rate of PM10 was 86.67%. Among 15 central air conditioning ventilation systems,13 systems were evaluated as level Ⅰ,and the other two was as level Ⅱand Ⅳ respectively.TAAlso,14 evaluated units got the fuzzy comprehensive indexes of central air ventilation less than 0.5.Conclusion The hygiene status of central air conditioning ventilation system in Jinhua is acceptable,and the management of hygiene quality should be strengthened.
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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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A transmissão intra-hospitalar da tuberculose consisteemumproblemade saúde ocupacional, e as medidas de controleefetivas incluem os controles ambientais que visam prevenir a disseminação dessa doença e reduzir as partículasinfecciosas aéreas. Trata-se de um estudo descritivo, realizado como objetivo de descrever a estrutura necessária paraimplantar e operacionalizar uma unidade de isolamento para tuberculose com pressão negativa do ar. A unidade foiprojetada comumsistema de climatização comcontrole de temperatura de 22±2 oC, recirculação do ar, filtragem HEPA,20 trocas de ar por hora e pressão negativa. Após a reforma da unidade e a implantação dos controles ambientais,o funcionamento do isolamento respiratório foi monitorizado por 12 meses. As ocasiões em que a pressão negativase tornou neutra foram identificadas pelos manômetros nos quartos e nos filtros, indicando a saturação deles e suasubstituição. Em seguida, a pressão negativa foi restabelecida. O investimento para a implantação do isolamento foide 75 mil dólares e o custo mensal de manutenção, 550 dólares. A unidade requer gerenciamento apropriado paraassegurar a proteção dos profissionais da saúde e demais pacientes.
Thenosocomial transmission of tuberculosis is a seriousoccupational health problem.Aneffectiveprevention of this diseaseincludes environmental measures to avoid its dissemination and to reduce the amount of droplet nuclei in the air. It is adescriptive study that aimed to describe the necessary structure for the implementation of an isolation roomwith negativeair pressure for patients with tuberculosis. The units were projected with HVAC system with temperature control at 22±2ºC, air recirculation system, HEPA filters, twenty two air changes per hour and negative air pressure. After repairs and theimplementation of the environmental control the functioning of the respiratory isolation wasmonitored for 12months. Inthe event of the negative air pressure becoming neutral the manometers in the room would display the filters saturationlevel and the need for their replacement. Soon after that the negative air pressure could be restarted. The isolation unitimplementationrequiredaninvestmentofUS$75,000.00 being themonthly repaircostUS$550.00.Therespiratoryisolationunit requires specific management strategies so as to ensure the protection of healthcare workers and patients.
La transmisión intrahospitalaria de la tuberculosis es un problema de salud en el trabajo y las medidas efectivas decontrol incluyen controles ambientales destinados a prevenir la diseminación de la enfermedad y reducir la cantidadde partículas infecciosas en el aire. Este estudio se realizó con el objetivo de describir la estructura necesaria paraimplementar y operar una unidad de aislamiento para la tuberculosis con presión de aire negativa. La unidad fuediseñada con un sistema de climatización con control de temperatura de 22 ± 2 ° C, recirculación del aire, filtros HEPA,veinte cambios de airepor horaypresión negativa. Después del proceso de reforma e implementación de los controlesambientales, el funcionamiento del aislamiento respiratorio fue monitoreado durante doce meses. Las ocasiones enque la presión negativa se convirtió en neutra fueron identificadas por manómetros en las habitaciones y en los filtros,señalando saturación y necesidad de sustitución. En seguida, la presión negativa fue restablecida. La inversión parainstalar el aislamiento fue de U$S 75.000,00yel costodemantenimiento mensual es de U$S 550,00. La unidad requiereestrategias de gestión adecuadas para garantizar la protección de los profesionales de la salud y de los pacientes.
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Humans , Risk Factors , Patient Isolation , Occupational Risks , Tuberculosis, Pulmonary/microbiology , Tuberculosis, Pulmonary/prevention & control , Tuberculosis, Pulmonary/transmission , Air ConditioningABSTRACT
Este trabalho apresenta resultados da pesquisa de contaminação dos filtros de condicionadores de ar instalados no setor residencial da cidade de Manaus. A pesquisa foi realizada no âmbito do projeto CAEMA (Condicionadores de Ar, Energia e Meio Ambiente) que consistiu na troca de aparelhos de ar condicionado ineficientes por eficientes na zona urbana da cidade. Dos 500 condicionadores de ar retirados do sistema pelo projeto, foram selecionados 50 filtros (10 por cento) para a análise de contaminação biológica, tendo sido identificada uma enorme variedade de agentes prejudiciais à saúde humana, entre bactérias e fungos. A bactéria mais vezes identificada foi a Staphylococcus sp e o fungo mais freqüente foi o Penicillium sp. Também foi possível verificar, por meio de entrevistas telefônicas junto a 37 usuários desses equipamentos, a grande incidência de sintomas associados a problemas de insuficiente qualidade de ar nos ambientes residenciais. Circunstâncias que motivaram a oportunidade desta pesquisa também impossibilitaram a coleta das amostras por unidade de volume, com os condicionadores ainda em funcionamento. Esse fato não comprometeu os objetivos da pesquisa, de promover a reflexão sobre os cuidados com a correta limpeza dos condicionadores de ar residenciais.
This work presents the results of a research about the contamination caused by air conditioners filters that are installed in the residential area in Manaus. The research took place in the scope of CAEMA's project (Conditioning of Air, Energy and Environment), which one consisted in changing inefficient conditional air devices for efficient ones in the urban zone of the city. Amongst 500 air conditioners removed of the system by the project, 50 filters (10 percent) were selected for biological contamination analysis, having been identified an enormous variety of agents, like bacteria and fungus, that are harmful for human health. The most identified bacterium was the Staphylococcus sp and the fungus more frequent was the Penicillium sp. Also it was possible to verify, by telephonic interviews with 37 users of these equipments, the great incidence of symptoms associates to the insufficient air quality in residential environments. The circumstances that had motivated the chance of this research, had also disabled that the assemble could be made per volume unit, with the conditioners still working. This fact did not compromise the quality of the work, neither the objectives to promote one reflection about the cares with the correct cleanness of the residential air conditioners.
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Air Conditioning , Air Pollution , Air Quality Control , Bacteria , Biological Contamination , Filters , FungiABSTRACT
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 investigate prevalent aeroallergens in ChongQing and their sensitization risk factors in children with allergic diseases,especially asthma.Methods:Skin prick tests with 13 standardized aeroallergens and questionnaires were used.A total of 298 patients,aged between 4~15 years and were diagnosed with allergic asthma and or allergic rhinitis,were investigated.Results:The total positive rate of allergen was 84.9%(253/298).The prevalence of aeroallergens were following:the first was house dust mite,cockroach followed,the third one was cat dander;the positive family history of asthma was 69.6%(116/230),asthma and rhinitis accounted for 67.2%(78/116)。Multivariate logistic regression analyses revealed that house dust mite was an independent risk factors for asthma(odds ratio Value(OR):2.602,95%CI:1.672～7.488),air conditioning had strong relationship with it(OR:1.659,95%CI:1.139～5.942).Conclusion:House dust mite is the major allergen of allergic diseases,especially asthma in ChongQing.Air conditioning is one of important risk factors for house dust mite sensitization.
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BACKGROUND: The operating room should provide an optimum environment that is safe for the patient and the working personnel. In this point of view, we investigated 8 items of temperature, humidity, air flow, noise, brightness, dust, CO2 and NO2. METHODS: Operating rooms, corridors and recovery rooms were tied as region I, II and III depending on their characteristics. 29 points were measured using appropriate instruments. After that, averaged values were calculated. RESULTS: Indoor climate (temperature, humidity and air flow) in region I were averaged 24.7, 65, 0.18/II were 25.5, 68, 0.18/III were 22.3 (degrees C), 56 (%), 0.22 (m/sec). Physcial condition (noise, brightness and dust) in region I were averaged 63, 295, 63/II were 67, 138, 87/III were 63 (db), 139 (lux), 26 (microgram/m3). Harmful gas (CO2 and NO2) concentration in region I were averaged 1152, 0.008/II were 913, 0.009/III were 1367 (ppm), 0.013 (ppm). CONCLUSIONS: Temperatures were appropriate but humidities were high except partial points. Air flow showed low values in average. Values of noise, dust and CO2 were relatively high. NO2 was low but brightness was variable. These mean that adequate improvement for quiet condition and air ventilation should be considered.
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Humans , Climate , Dust , Humidity , Noise , Operating Rooms , Recovery Room , VentilationABSTRACT
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.