Assessment of airborne microorganism contamination in an industrial area characterized by an open composting facility and a wastewater treatment plant

In order to assess the potential exposure hazard to workers and people living in the immediate surroundings of an area characterized by an open composting facility and a wastewater treatment plant, a quantitative and a qualitative analysis of airborne microorganisms were carried out. Air sampling was performed once a week for four consecutive weeks in summer and winter. Six sites were selected as air sampling sites: one was upwind at approximately 40 m from the facilities; the other five were downwind at increasing distances from the facilities, with the furthest at 100 m away. Monitoring permitted us to verify the influence that the composting activities and wastewater treatment had on the bacterial and fungal contamination of the air. The results obtained have been expressed by means of contamination indexes that have already been used in previous works: a major microbiological contamination near the plants was evidenced. Near the facilities, mesophilic bacteria, psychrophilic bacteria and microfungi showed the highest median concentrations, respectively, of 307.5, 327.5 and 257.5 CFU/m³. Moreover, the season generally influenced the concentration of the bacteria as well as of the fungi; higher in summer than in winter. The contamination index global index of microbial contamination (GIMC/m³) showed mean values of 4058.9 in summer and 439.7 in winter and the contamination index—amplification index (AI) showed values of 4.5 and 1.1 in the same seasons, respectively. Controlling the seasonal effect, mesophilic bacteria, Pseudomonas spp. and Enterobacteriaceae showed a significant decline in concentration with respect to upwind air samples and with increasing distance. Both GIMC and AI showed a significant decline with respect to upwind air samples by increasing the distance from facilities after adjusting for the seasonal effect. In conclusion, even if these plants do not represent a potential risk for nearby populations, they may pose a potential health risk for workers.     

Microbial air monitoring in operating theatre: active and passive samplings

Microbial air contamination was evaluated in 11 operating theatres using active and passive samplings. SAS (Surface Air System) air sampling was used to evaluate cfu/m3 and settle plates were used to measure the index of microbial air contamination (IMA). Samplings were performed at the same time on three different days, at three different times (before, during and after the surgical activity). Two points were monitored (patient area and perimeter of the operating theatre). Moreover, the cfu/m3 were evaluated at the air inlet of the conditioner system. 74.7% of samplings performed at the air inlet and 66.7% of the samplings performed at the patient area before the beginning of the surgical activity (at rest) exceeded the 35 cfu/m3 used as threshold value. 100% of IMA values exceeded the threshold value of 5. Using both active and passive sampling, the microbial contamination was shown to increase significantly during activity. The cfu values were higher at the patient area than at the perimeter of the operating theatre. Mean values of the cfu/m3 during activity at the patient area ranged from a minimum of 61+/-41 cfu/m3 to a maximum of 242+/-136 cfu/m3; IMA values ranged from a minimum of 19+/-10 to a maximum of 129+/-60. 15.2% of samplings performed at the patient area using SAS and 75.8% of samplings performed using settle plates exceeded the threshold values of 180 cfu/m3 and 25 respectively, with a significant difference of the percentages. The highest values were found in the operating theatre with inadequate structural and managerial conditions. These findings confirm that the microbiological quality of air may be considered a mirror of the hygienic conditions of the operating theatre. Settle plates proved to be more sensitive in detecting the increase of microbial air contamination related to conditions that could compromise the quality of the air in operating theatres.     

Inconsistent correlation between aerobic bacterial surface and air counts in operating rooms with ultra clean laminar air flows: proposal of a new bacteriological standard for surface contamination

The relationship between surface contamination (cfus/m2/h) with particles carrying aerobic bacteria and corresponding air contamination rates (cfus/m3) was evaluated in operating rooms (OR) equipped with ultra clean vertical or horizontal laminar airflow (LAF). For the evaluation we collected data during strictly standardized sham operations using non-woven disposable or cotton clothing. Air contamination in the wound and instrument areas (Casella slit sampler) was related to the surface contamination rate (settle plates) in the same areas and in addition, on the patient chest. Typically, the mean surface counts were 20-70 cfus/m2/h and the air counts 1-2 cfus/m3 in disposable clothing experiments, whilst the use of cotton clothing resulted in higher counts of 100-200 cfus/m2/h (wound P > 0.05, patient P > 0.05, instruments P < 0.01) and 4 cfus/m3 (P < 0.02-0.001). In the vertical LAF, taking both disposable and cotton clothing operations together, the surface and air contamination rates (surface/air ratio SAR) were highly correlated (P = 0.02-0.004) and the ratio varied between 18:1 and 50:1 with a mean for wound air of 36:1. Using only disposable clothing in the vertical LAF, the number of significant correlations was reduced. With cotton clothing experiments in vertical LAF and in the horizontal LAF using disposable clothing, no significant correlation between surface and air contamination was found. The wide variation of SAR values and the inconsistent relationship between surface and air counts indicates that measurement of OR air contamination represents an unhelpful method for assessment of surgical site contamination in LAF units. We propose instead that colony counts on sedimentation plates is a clinically more relevant indicator of bacterial OR contamination in LAF units. In addition to the current bacteriological standard for ultra clean OR air of (< 10 cfus/m3) we suggest a corresponding standard for the surface contamination rate of < 350 cfus/m2/h.     

Bacterial contamination of the air in different operating rooms

Bacteria air samples were taken in the operating rooms, with no people present, to specify the level of air contamination and suggest bacteriological standards for different operating rooms. In the first step of this study, for 5 months the air contamination mean value of operating rooms, ventilated at 15 changes/hour was 18.5 Cfu/m3 +/- 1.9. In the second part of the study, during two years, 1 381 air samples were taken in 8 different operating rooms. The mean values of air contamination range from 1.4 Cfu/m3 in a Charnley isolator system to 121 Cfu/m3 in an operating room ventilated at 7.5 changes per hour. As a general rule, the airborne contamination is more significant in the oldest operating rooms than in the new one with filtrated air. The variations observed between 1981 and 1982 are explained by technical modifications of the system or progress in control of operating room conditions. Measurements of the bacterial contamination of the air give useful informations, but it is however better to ensure that the specifications for volume air supply and positive air pressure in the operating theatres are being fulfilled. The airborne bacterial concentration in a modern ventilated operating room should not exceed 30 Cfu/m3.     

Fungal contamination in hospital environments.

OBJECTIVES: To assess the degree of fungal contamination in hospital environments and to evaluate the ability of air conditioning systems to reduce such contamination. METHODS: We monitored airborne microbial concentrations in various environments in 10 hospitals equipped with air conditioning. Sampling was performed with a portable Surface Air System impactor with replicate organism detection and counting plates containing a fungus-selective medium. The total fungal concentration was determined 72-120 hours after sampling. The genera most involved in infection were identified by macroscopic and microscopic observation. RESULTS: The mean concentration of airborne fungi in the set of environments examined was 19 +/- 19 colony-forming units (cfu) per cubic meter. Analysis of the fungal concentration in the different types of environments revealed different levels of contamination: the lowest mean values (12 +/- 14 cfu/m(3)) were recorded in operating theaters, and the highest (45 +/- 37 cfu/m(3)) were recorded in kitchens. Analyses revealed statistically significant differences between median values for the various environments. The fungal genus most commonly encountered was Penicillium, which, in kitchens, displayed the highest mean airborne concentration (8 +/- 2.4 cfu/m(3)). The percentage (35%) of Aspergillus documented in the wards was higher than that in any of the other environments monitored. CONCLUSIONS: The fungal concentrations recorded in the present study are comparable to those recorded in other studies conducted in hospital environments and are considerably lower than those seen in other indoor environments that are not air conditioned. These findings demonstrate the effectiveness of air-handling systems in reducing fungal contamination.     

The impact of environmental air pollution and incidence of acute respiratory viral infections

The paper characterizes diffuse ambient air pollution (P index) in accordance with the data of Kazan stationary stations in 1996-2000. The incidence of childhood respiratory diseases is studied for the same period. A correlation between morbidity and ambient air pollution is analyzed. There is a direct significance correlation between Kazan's ambient air pollution and morbidity rates in children aged 0-14 years, which is as follows rxy +/- m = 0.626 +/- 0.104. The regression coefficient has been established, which is Ry/x = 0.183 when the atmospheric contamination is changed by one unit.     

Determination of tricresyl phosphate air contamination in aircraft

Monitoring of tricresyl phosphate (TCP) contamination of cockpit air was undertaken in three types of military aircraft [fighter trainer (FT), fighter bomber (FB), and cargo transport (CT) aircraft]. The aircraft had a previous history of pilot complaints about cockpit air contamination suspected to originate from the engine bleed air supply through the entry of aircraft turbine engine oil (ATO) into the engine compressor. Air samples were collected in flight and on the ground during engine runs using sorbent tubes packed with Porapak Q and cellulose filters. A total of 78 air samples were analysed, from 46 different aircraft, and 48 samples were found to be below the limit of detection. Nine incidents of smoke/odour were identified during the study. The concentrations of toxic o-cresyl phosphate isomers were below the level of detection in all samples. The highest total TCP concentration was 51.3 μg m(-3), while most were generally found to be <5 μg m(-3) compared with the 8-h time-weighted average exposure limit of 100 μg m(-3) for tri-o-cresyl phosphate. The highest concentrations were found at high engine power. Although TCP contamination of cabin/cockpit air has been the subject of much concern in aviation, quantitative data are sparse.     

Two Years of a Fungal Aerobiocontamination Survey in a Florentine Haematology Ward

The control of microbial air contamination in hospital wards has assumed great importance particularly for those hospital infections where an airborne infection route is hypothesised, such as aspergillosis. Invasive aspergillosis represents one of the most serious complications in immunocompromised patients. For some authors there is a direct association between this pathology and the concentrations of Aspergillus conidia in the air; in addition, reports of aspergillosis concurring during building construction have been frequent. In this study, two haematology wards were monitored for about 2 years in order to make both a qualitative and quantitative evaluation of fungal burden in the air, also in relation to major construction and demolition work taking place in the same building. Air samples were taken from the hospital rooms of neutropenic patients, in the corridors of their ward and outside the building. Total fungal concentration resulted higher outside (mean 572 Colony Forming Units/m3 of air), lower in the corridors (147 CFU/m3) and even lower in the rooms (50 CFU/m3). In all the samples we found the development of at least one fungal colony. Cladosporium was the most frequently isolated genus (57%), in contrast to Aspergillus spp. (2%). The average concentration of Cladosporium spp. was 24 CFU/m3 in the rooms, 78 CFU/m3 in the corridors and 318 CFU/m3 outside. The average concentration of Aspergillus spp. was 1.2 CFU/m3 in the rooms, 3.5 CFU/m3 in the corridors, 5.6 CFU/m3 outside. Our observations show low concentrations of Aspergillus fumigatus and A. flavus in all the environments examined and particularly in the rooms (0.09 and 0.10 CFU/m3 respectively); this observation could explain the absence of cases of invasive aspergillosis during the period of air monitoring in the two haematology wards.     

Sanitary and epidemiological evaluation of the ventilation and air-conditioning systems of public buildings

The microbial contamination of ventilation and air conditioning systems was examined in the administrative buildings. The author proposes a set of indicators, methods for determining the scope of investigations, as well as sampling tactics and criteria for evaluating the microbial contamination of the ventilation and air-conditioning systems. The content of yeasts and molds in the delivered air has been found to be of importance for evaluating the sanitary-and epidemiological state of ventilation systems.     

Correlation between surface and air counts of particles carrying aerobic bacteria in operating rooms with turbulent ventilation: an experimental study.

Airborne contamination with bacteria-carrying particles (cfu/m3) and their sedimentation rate (cfu/m2/h) was compared in an operating room (OR) equipped with two turbulent ventilation systems. One was a thermally based system with inlet of cool clean air at the floor level and evacuation of the air at the ceiling by convection (17 air changes/h). The other was a conventional plenum pressure system with air supply at the ceiling and evacuation at the floor level (16 air changes/h). The study was made during rigidly standardised sham operations (N = 20) performed in the same OR by the same six member team wearing non-woven disposable or cotton clothing. Airborne contamination in the wound and instrument areas was related to the surface contamination rate in the same areas and in addition, on the patient chest and in the periphery of the OR. With the exception of the periphery of the OR, the surface and air contamination rates were highly correlated in both ventilation systems (P = 0.02-0.0006, r2 = 0.52-0.79). This was also true particularly when disposable clothing was used while the correlation was weaker in cotton clothing experiments. An equation describing the relation between surface and air counts is given. Typically, the surface counts were numerically 16-fold the air counts, i.e., the number of colonies sedimenting on four 14 cm-diameter agar plates during 1 h will almost equal the number of airborne cfu per m3. We propose, that sedimentation plates represent not only a technically easier method than air sampling but when correctly used, are also the most realistic indicator of airborne bacterial OR contamination in areas critical for surgery.     

Monitoring air sampling in operating theatres: can particle counting replace microbiological sampling?

Microbiological contamination of air in the operating room is generally considered to be a risk factor for surgical site infections in clean surgery. Evaluation of the quality of air in operating theatres can be performed routinely by microbiological sampling and particle counting, but the relationship between these two methods has rarely been evaluated. The aim of this study was to determine whether particle counting could be predictive of microbiological contamination of air in operating rooms. Over a three-month period, air microbiological sampling and particle counting were performed simultaneously in four empty operating rooms belonging to two surgical theatres equipped with conventional ventilation via high-efficiency particulate air filters. Correlation between the two methods was measured with Spearman's correlation coefficient. The ability of particle counting to discriminate between microbiological counting values higher and lower than 5 colony-forming units (CFU)/m3 was evaluated using receiver-operating characteristic (ROC) analysis. Microbiological counting ranged from 0 to 38CFU/m3, while the particle counts ranged from 0 to 46 262/m3. Methods of microbiological and particle counting did not correlate (Spearman correlation coefficient=0.06, P=0.6). Using the ROC curve, no particle count value could be predictive of a microbiological count higher than 5CFU/m3. The results of the current study suggest that there is no reason to replace microbiological sampling with particle counting for routine evaluation of microbiological contamination in conventionally ventilated operating theatres.     

医用压缩空气净化及监测研究进展

 压缩空气广泛应用于医疗机构内,被称为是生命支持系统。然而压缩空气质量,尤其是微生物含量并没有引起人们的广泛关注。此文就压缩空气的制备,现执行的国内外标准及存在的问题,净化措施和微生物监测技术的相关文献等内容进行归纳总结,旨在明晰压缩空气污染的来源、控制策略和监测方法,为今后开展相关监测研究,制定标准、规范提供参考。     

Hygienic evaluation of air and soil pollution with mercury in the area of location of a coke plant

It has been established that processes of coal carbonization are accompanied by intensive mercury discharge into the air and soil. The maximum levels of ambient air contamination by mercury are determined 0.5 km away from the source--0.0016 mg/m3, 3 km away from the source--lower than 0.00024 mg/m3. Technogenic area of mercury is almost twice the territory of the plant, and it is stretched along the prevalent direction of the winds. Mercury concentrations at different distances away from the plant were 2.76 mg/kg (0.5 km), 1.97 mg/kg and 0.26 mg/kg. Simultaneous isolation of mercury from coals in the process of coal carbonization is recommended.     

Tests of the microbiologic barrier in sterile packaging

After decontamination, cleaning, maintenance and functional testing, sterilised items must be packed suitably. The package must protect sterilised items against microbial contamination during removal from the sterilising chamber, and during storage or transport until use. The ability of any given pack to withstand penetration by bacteria is termed bacterial barrier efficiency. The assurance to keep the contents of the packaging sterile is determined by quality of the materials and the quality of seals. The research was done to proof the microbial barrier, determined by quality of the packaging materials/systems used to sterilization in hospital practice in Poland. 4 packaging materials and 4 types of containers were tested. In all used methods the growth of microorganisms indicated the lack of the bacterial efficiency, the lack of growth--the bacterial barrier efficiency. It was proved that two tested specialistic sterilization papers, non woven material and specialistic containers (metal with a filter or valve, plastic with a filter) are effective microbial barriers because it was no microorganisms growth. It has been determined that sulphite bleachery paper of 60 g/m2 and Schimmelbusch container do not provide the microbial barrier. Based on the performed studies it has been determined that sulphite bleachery paper and Schimmelbusch container can not be used as sterilization packaging system in sterilization practice in hospitals.     

Residual tetrachloroethylene in dry-cleaned clothes

A large amount of residual tetrachloroethylene (TCE), up to 13.6 mg/g, was found in dry-cleaned clothes. The amounts varied among dry-cleaning establishments as well as with the type of fiber. The causes of these variations are discussed. Air TCE concentrations in the closed environment of dry-cleaning outlets were elevated: the highest reading was 4.8 mg/m3. The expired air of outlet employees also showed an increased level of TCE (average, 36.9 micrograms/m3). Increased air contamination from TCE released from dry-cleaned clothes was also observed in the home of a consumer. To reduce environmental contamination from TCE released from any of these sources, the amount of residual TCE in dry-cleaned clothes should be minimized.     

Airborne microbial contents in two types of swine confinement buildings in Quebec

Airborne microorganisms were isolated with a sampler in two types of swine confinement buildings (farrowing units and fattening units). Respirable (particles less than 5 microns) and total dust fractions were obtained. Samplings were repeated every 2 weeks for a total of 6 samplings per unit between January and April. The predominant microorganisms isolated were bacteria (up to 1.25 x 10(6) CFU/m3) with an important fraction in the respirable size range (up to 0.5 x 10(6) CFU/m3). Only small quantities of gram-negative bacteria, yeasts, and molds were found. Identification of the colonies isolated revealed a great diversity of microorganisms present in the air of the different buildings. Enterobacter agglomerans, Moraxella, Acinetobacter calcoaceticus, and Pseudomonas were the most frequently identified bacteria. Scopulariopsis, Aspergillus, Penicillium, and Candida were the most numerous fungi. Faenia rectivirgula, the causative agent of farmer's lung, was not a major contaminant. The results show some differences in airborne microbial contamination between farrowing and fattening units; the distinction, however, is not clear-cut and was observed only for the total bacteria. The level of airborne microbial contamination in swine units does not significantly vary as a function of the outside temperature. Some species of bacteria and fungi isolated in this study are known to induce extrinsic allergic alveolitis. Other fungi are known to be potentially pathogenic for man. The air of swine confinement buildings is highly contaminated with bacteria, yeasts, and molds at a level up to 1200 time higher than so-called "normal air."     

Substantiation of the tactics of short-wave ultraviolet irradiation of the air in hospital premises

It has been found out, that the level of microbic dissemination of the air of premises for the treatment of children increases 3-10 times following carrying out various functional activities in them. To reduce air contamination it is reasonable to use irradiation of bactericidal lamps of DB 30-1 type with specific power of 1.5 W/m3 for the first 20 min. after the work has been fulfilled in the premises.     

Reduction in MRSA environmental contamination with a portable HEPA-filtration unit

There is renewed interest in the hospital environment as a potentially important factor for cross-infection with methicillin-resistant Staphylococcus aureus (MRSA) and other nosocomial pathogens. The aim of this study was to evaluate the effectiveness of a portable high-efficiency particulate air (HEPA)-filtration unit (IQAir Cleanroom H13, Incen AG, Goldach, Switzerland) at reducing MRSA environmental surface contamination within a clinical setting. The MRSA contamination rate on horizontal surfaces was assessed with agar settle plates in ward side-rooms of three patients who were heavy MRSA dispersers. Contamination rates were measured at different air filtration rates (60-235 m(3)/h) and compared with no air filtration using Poisson regression. Without air filtration, between 80% and 100% of settle plates were positive for MRSA, with the mean number of MRSA colony-forming units (cfu)/10-h exposure/plate ranging from 4.1 to 27.7. Air filtration at a rate of 140 m(3)/h (one patient) and 235 m(3)/h (two patients), resulted in a highly significant decrease in contamination rates compared with no air filtration (adjusted rate ratios 0.037, 0.099 and 0.248, respectively; P < 0.001 for each). A strong association was demonstrated between the rate of air filtration and the mean number of MRSA cfu/10-h exposure/plate (P for trend < 0.001). In conclusion, this portable HEPA-filtration unit can significantly reduce MRSA environmental contamination within patient isolation rooms, and this may prove to be a useful addition to existing MRSA infection control measures.     

2家甘蔗制糖企业蔗渣尘关键控制点与微生物污染状况调查

目的 调查广西2家甘蔗制糖企业蔗渣尘关键控制点与微生物污染状况.方法 针对A、B两家企业作业场所中的微生物采样采用自然沉降法进行检测.结果 甘蔗堆场、甘蔗落料口、打包机蔗渣尘关键控制点的粉尘浓度在0.96～8.89 mg/m3,甘蔗堆场、甘蔗落料口、打包机的菌落总数(均值)分别为240 cfu/m3(A)、357 cf...     

不同类型坑道空气真菌厌氧菌污染调查

目的通过51条不同类型坑道空气微生物监测，为坑道安全保障提供依据。方法用撞击法和沉降法监测空气细菌总数、真菌数、链球菌及厌氧菌数。结果1．空气细菌总数及链球菌数基本正常。2．半密闭型坑道空气真菌数最高，通道及房间中位数分别为5950cfu／m^3及9500cfu／m^3。3．密闭型坑道通道空气厌氧菌数分别是半密闭型及通风型通道的4．2倍及3．8倍。结论坑道空气中含有大量真菌及厌氧菌，对进驻人员健康有一定威胁。