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1.
This study quantified the levels of airborne microorganisms in six swine farms with more than 10,000 pigs in subtropical Taiwan. We evaluated breeding, growing, and finishing stalls, which were primarily open-air buildings, as well as partially enclosed farrowing and nursery piggeries. Airborne culturable bacteria, gram-negative bacteria, and fungi were placed on appropriate media by using an all-glass impinger or single-stage Andersen microbial sampler. Results showed that mean concentrations of culturable bacteria and gram-negative bacteria were 3.3 × 10 5 and 143.7 CFU/m 3, respectively. The concentration of airborne culturable fungi was about 10 3 CFU/m 3, with Cladosporium the predominant genus. The highest airborne levels of culturable bacteria and gram-negative bacteria were identified in the finishing units. The air of the nursery stalls was the least contaminated with culturable and gram-negative bacteria. Irregular and infrequent cleaning, high pig density, no separation of wastes from pen floors, and accumulation of water as a result of the processes for cleaning and reducing pig temperature possibly compromise the benefits of the open characteristic of the finishing units with respect to airborne bacterial concentration. 相似文献
2.
Three different methods of estimating airborne bacteria were compared. An Anderson sampler, a slit sampler, an impinger, and filter samplers with gelatine filters or membrane filters were tested for collection efficiency. The comparisons were made in laboratory experiments with an aerosol of Staphylococcus epidermidis or Serratia marcescens, in field experiments in two different industries, i.e., cotton mill and sewage plant, and in experiments with skin fragment sampling. Experiments were also performed estimating the total number of viable microorganisms on the airborne particles. The Andersen sampler gave the highest bacterial counts in all environments tested. The slit sampler gave statistically lower counts only in the aerosol experiments and cotton mill experiments, where the size of the majority of the particles carrying visible bacteria was 2 to 6 micrometers or smaller. In the sewage plant and skin fragment experiments, where the particles were mainly 5 micrometers or larger, the difference was not significant. The filters were efficient in sampling in skin fragment experiments only. With the agar impingement method, the total viable cell count showed a rising index value with increasing particle size. A mean of 13 bacteria was found per particle in the cotton mill, a mean of 24 in the sewage plant, and a mean of 147 in skin fragment experiments. 相似文献
3.
Alfresco (def. clean, outdoor) airborne bacteria were collected with a commercially available wet-cyclone bioaerosol sampler
to demonstrate its use, sample processing and resultant observations of total and culturable bacteria in mid-summer in the
mid-Willamette River Valley, OR. Some critiques of the system are given. The maximum and minimum total and culturable airborne
bacterial concentrations in the samples were 5.9 × 10 5 and 8.8 × 10 2 cells m −3, and 1.3 × 10 4 and 3.1 CFU m −3, respectively. What is thought to be a diurnal cycle was also observed for both fractions with highest concentrations during
the day and lowest at dawn and dusk. The culturable bacteria as a percentage of the total, was maximal at mid-day (≈ 3%) and
minimal at early morning and late evening (≈ 0.5–2%). Contrarily, the total bacteria in the downwind dust plume of a grass
seed combine was 2.9 × 10 6 cells m −3 and of these approximately 73% were culturable, a much greater culturable percentage than found in the alfresco outdoor atmosphere. 相似文献
4.
The frequency of fungal spores in the air of three different sections of a rural bakery was analyzed using a Burkard personal slide sampler and Andersen two stage viable sampler. In average concentration of spores (No./m 3) was 228–26770/m 3 and concentration of viable colony forming units (CFU/m 3) was 65-2061 CFU/m 3. Dominant fungus species both culturable and nonculturable, were species of Aspergillus and Penicillium, Cladosporiumsp., Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Cladosporium cladosporioides, Penicillium citrinum and Alternaria alternata. Seasonal variations in the spore concentrations were clearly observed in case of some fungi. Total culturable mould concentration of different bakery sections sometimes exceeded the acceptable limit for a healthy indoor environment. Antigenic extracts prepared from some dominant culturable fungi showed high level of allergenicity in skin prick tests indicating that they could be responsible for allergic respiratory dysfunction of bakery workers.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
5.
Thailand border market is where the local Thais, Cambodians, Laotians, and Burmeses exchange their goods and culture at the
border checkpoints. It is considered to be the source of aerial disease transmission especially for foreigners because it
is always very crowded with people from all walks of life. Unhealthy air quality makes this area high risk of spread of airborne
diseases. This study assessed airborne concentrations of bacteria and fungi in a border market to improve exposure estimates
and develop efficient control strategies to reduce health risk. The density and distribution of airborne bacteria and fungi
were investigated in the Chong Chom border market in Surin Province, Thailand. Eighteen air sampling sites were taken from
outdoors and various work environments including indoor footpaths, wooden handicraft shops, electronic shops, the secondhand
clothing shops, and fruit market areas. Exposed Petri plate method and liquid impinger sampler were used for sampling at the
breathing zone, 1.5 m above the floor level, during weekend and holiday. Meteorological factors such as relative humidity,
temperature, and light intensity were collected by portable data logger. The relative humidity was 67–73%, and temperature
29–33°C, and light varied between 18 and 270 Lux m −2. Gram-positive and Gram-negative bacteria were found at a mean value of 10 4 CFU m −3, and airborne fungi of 10 3 CFU m −3 were recorded. The highest concentration of culturable airborne microorganisms was found along the indoor footpath (9.62 × 10 4 CFU m −3 and 750.00 CFU/plate/h for impingement and sedimentation methods, respectively), the fruit market area (7.86 × 10 4 CFU m −3 and 592.42 CFU/plate/h for impingement and sedimentation methods, respectively), and the secondhand clothing shop (4.59 × 10 3 CFU m −3 and 335.42 CFU/plate/h for impingement and sedimentation methods, respectively) for Gram-positive bacteria, Gram-negative
bacteria, and fungi, respectively. The lowest concentration of Gram-positive bacteria, Gram-negative bacteria, and fungi was
found only at the outdoor area at 1.53 × 10 4 CFU m −3, 0.93 × 10 4 CFU m −3 and 0.80 × 10 3 CFU m −3 by means of impingement method and 136.67 CFU/plate/h, 69.25 CFU/plate/h, and 62.00 CFU/plate/h by means of sedimentation
methods for Gram-positive bacteria, Gram-negative bacteria, and fungi, respectively. The most frequently present airborne
bacteria were identified as Bacillus, Corynebacteria, Diplococcus, Micrococcus, Acinetobacter, Alcaligenes, Enterobacter, and spore former rods. Acremonium, Aspergillus, Cladosporium, Penicillium, and Sporotrichum were the most frequently found aerosol fungi genera. The distribution of airborne microorganisms correlated with relative
humidity and light factors based on principal component analysis. In conclusion, the border market is a potential source of
aerial disease transmission and a various hazards of bioaerosols for workers, consumers, sellers, and tourists. The bioaerosol
concentration exceeded the standard of occupational exposure limit. Many major indicators of allergenic and toxigenic airborne
bacteria and fungi, Acinetobacter, Enterobacter, Pseudomonas, Cladosporium, Alternaria, Aspergillus, and Penicillium, were found in the various market environments. 相似文献
6.
Airborne bacteria are important biological components of bioaerosol and play an important role in ecosystem. Bacteria at a
high concentration in the atmosphere can result in biological air pollution and all kinds of diseases. In this study, a systematical
survey on the culturable airborne bacteria was carried out for 1 year at three sites in Beijing urban area. Results showed
that concentrations of culturable bacteria ranged from 71 colony forming units (CFU)/m 3 to 22,100 CFU/m 3, and the mean was 2,217 CFU/m 3. Bacterial concentrations at the human activity-enriched site (RCEES) and the highly trafficked site (XZM) were virtually
the same point. They were significantly higher than those at the greener site (BBG). Significant variation in bacterial concentrations
in different seasons was observed at RCEES and XZM with higher concentrations in summer and autumn. In a single day, significantly
lower concentrations were detected at 13:00 hours through all sampling sites. In this study, 165 species in 47 genera of culturable
bacteria were identified. Micrococcus was one of the most dominant bacterial groups and contributed to approximately 20∼30% of the total bacterial concentration,
followed by Staphylococcus, Bacillus, Corynebacterium, and Pseudomonas. The bacterial species with a high concentration percentage included Micrococcus luteus and Micrococcus roseus. 相似文献
7.
This study investigates the exposure of workers to biological particles in a poultry litter burning plant in operation. The
microorganism concentrations were examined at different workplaces during procedures leading to increased emissions. The concentrations
of culturable airborne mesophilic, xerophilic and thermophilic microorganisms in the ambient air were tested inside and outside
of the burning plant using two different methods of measuring. The focus of this study was on the quantitative evaluation
of culturable bacteria as well as the quantitative and qualitative evaluation of gram-negative bacteria, fungi and thermophilic
actinomycetes. The maximum airborne concentrations were found in the delivery hall. Mesophilic bacteria concentrations reached
up to 1.7 × 10 6 CFU/m 3; gram-negative bacteria up to 9.1 × 10 2 CFU/m 3. Fungal propagule concentrations for xerophilic fungi were between 1.2 × 10 3 and 2.9 × 10 4 CFU/m 3 and for mesophilic fungi between 4.4 × 10 2 and 2.9 × 10 4 CFU/m 3. Among fungi, Aspergillus niger, Eurotium herbariorum and Scopulariopsis brevicaulis species were dominant. Thermophilic actinomycetes reached airborne concentrations of 8.7 × 10 4 CFU/m 3, with increased concentrations of the pathogens causing extrinsic allergic alveolitis. The high concentrations of airborne
microorganisms in poultry litter burning plants and the potential hazard of the intake of microorganisms including potential
pathogens require the introduction of consistent measures in both technical areas and personnel management. 相似文献
8.
A set of simultaneously collected quantitative measurements of 12 meteorological and 6 culturable atmospheric bacterial (CAB)
variables was made over a grass seed field during several early, mid, and late summer days. The observation site was located
between the Cascade and Coastal Mountain Ranges near Corvallis in the Willamette Valley, Oregon. Principal component analysis
identified those meteorological variables that had the highest loadings in six eigenvectors that account for 95.9% of variation
in the data factors, i.e., temperature @ 6.3 m above ground level (AGL), wind velocity @ 10.0 m AGL, wind velocity difference
@ 1.7–10.0 m, barometric pressure, wind direction standard deviation, and wind direction. When these variables were used in
a cluster analysis, they formed three statistically distinct meteorological variable clusters with means at ca. “midnight”,
ca. “midday”, and ca. “evening.” The highest mean density of CAB (i.e., 153.4 ± 162.5 CFU/m 3) was associated with the “midday” meteorological Cluster-1 that had warm, dry “gentle breezes” from the southeast, in the
relatively bacteria loaded Willamette Valley air. The lowest mean density of CAB (i.e., 35.5 ± 24.1 CFU/m 3) was associated with meteorological Cluster-3 in the late afternoon and “evening” occurring during the hottest and driest
part of the day with “fresh breezes” coming from the north northwest in air off the Pacific Ocean. Finally, the last cluster,
Cluster-2 occurred about midnight and had an intermediate density of CAB (74.2 ± 76.2 CFU/m 3) in “light air” coming from the northwest, perhaps off the Pacific Ocean. The CAB associated with each of the three meteorological
clusters was only partially statistically distinct. Partially because the CAB in both the Pacific Ocean derived air masses
of the “evening” Cluster-3 and “midnight” Cluster-2 were not statically separable, though both were statistically separable
from the midday, Willamette Valley derived Cluster-1. Further indicating their common source, both Pacific Ocean derived air
masses had very similar percentages of pigmented bacteria, which were dissimilar to the pigmented bacterial population density
in the Willamette Valley air masses. In short, it is speculated that “midnight” atmosphere may simply contain the settling
concentrated residual bacterial particles in the abated fresh Pacific Ocean breezes after sundown. It is clearly shown that
with the methods employed, it is possible to associate the uniqueness of the quantity, and to a lesser extent the quality,
of the CAB population with the atmospheric conditions reported herein. From this project comes speculation that the strategies
relating the quasi-conservative bacterial populations associated with distinct but nonconservative air mass properties can
help to better understand more of the bacterial dynamics found in such situations. And to a further extent, molecular biological
methods could be applied to identify bacterial taxa in specific air masses. 相似文献
9.
A unique agar drum sampler is described which indicates, continuously, the number of viable, bacterial particles per unit volume of air at the time and point of sampling. By selection of the timer and the sampling rate the sampler is suitable for quite a wide range of concentration and time. An impaction line of 484 in. greatly increases the capacity of this device over slit samplers and other instruments designed to give time-concentration data for viable airborne particles. This sampler should prove useful for: (i) monitoring airborne bacteria in hospitals, public places, and food and industrial plants; (ii) decay rate studies of bacterial aerosols; (iii) evaluation of aerial germicides; (iv) determination of effectiveness of air conditioning systems in removing airborne bacteria; and (v) many other studies in aerobiology. 相似文献
10.
Air filters efficiency is usually determined by non-biological test aerosols, such as potassium chloride particles, Arizona
dust or di-ethyl-hexyl-sebacate (DEHS) oily liquid. This research was undertaken to asses, if application of non-biological
aerosols reflects air filters capacity to collect particles of biological origin. The collection efficiency for non-biological
aerosol was tested with the PALAS set and ISO Fine Test Dust. Flow rate during the filtration process was 720 l/h, and particles
size ranged 0.246–17.165 μm. The upstream and downstream concentration of the aerosol was measured with a laser particle counter
PCS-2010. Tested bioaerosol contained 4 bacterial strains of different shape and size: Micrococcus luteus,
Micrococcus varians, Pseudomonas putida and Bacillus subtilis. Number of the biological particles was estimated with a culture-based method. Results obtained with bioaerosol did not confirmed
100% filters efficiency noted for the mineral test dust of the same aerodynamic diameter. Maximum efficiency tested with bacterial
cells was 99.8%. Additionally, cells reemission from filters into air was also studied. Bioaerosol contained 3 bacterial strains:
Micrococcus varians, Pseudomonas putida and Bacillus subtilis. It was proved that the highest intensity of the reemission process was during the first 5 min. and reached maximum 0.63%
of total number of bacteria retained in filters. Spherical cells adhered stronger to the filter fibres than cylindrical ones.
It was concluded that non-biological aerosol containing particles of the same shape and surface characteristics (like DEHS
spherical particles) can not give representative results for all particles present in the filtered air. 相似文献
11.
There are practical and valid reasons topresent biological field trial referenceresults as agent containing particles per literof air (ACPLA). However, workers in biologicalaerosol research have a need to know how manyviable individual organisms are contained in asingle particle of a given diameter. Anecdotalevidence may exist suggesting that the task hasbeen accomplished but without a way toreplicate the measurements, it is difficult toaccept unsubstantiated claims. It is verydifficult to declare a finite number thatsatisfies all the experimental requirements, asthe problem is a statistical probability issue. This paper describes a method for estimatingthe number with practical instructions forreplicating the work in other laboratories.The test aerosol was contained in a 90 m 3chamber at concentrations as low as 5 ACPLA. Amodified version of slit sampler collectedviable particles. A statistical method was usedto demonstrate sampling predictability at 95%confidence level. By using glass fiber filtersmounted in a dichotomous sampler, samplingefficiencies were estimated for a variety ofcommon aerosol collectors. The accumulated datapermitted the estimation of the number ofviable spores per particle. For a 2.5 to4 µm particle, arguments have beenpresented for considering 4.5 as the mostprobable ACPLA value. 相似文献
12.
The influence of sample-collection-time on the recovery of culturable airborne microorganisms using a low-flow-rate membrane-filtration
unit and a high-flow-rate liquid impinger were investigated. Differences in recoveries were investigated in four different
atmospheric environments, one mid-oceanic at an altitude of ~10.0 m, one on a mountain top at an altitude of ~3,000.0 m, one
at ~1.0 m altitude in Tallahassee, Florida, and one at ~1.0 m above ground in a subterranean-cave. Regarding use of membrane
filtration, a common trend was observed: the shorter the collection period, the higher the recovery of culturable bacteria
and fungi. These data also demonstrated that lower culturable counts were common in the more remote mid-oceanic and mountain-top
atmospheric environments with bacteria, fungi, and total numbers averaging (by sample time or method categories) <3.0 colony-forming
units (CFU) m −3. At the Florida and subterranean sites, the lowest average count noted was 3.5 bacteria CFU m −3, and the highest averaged 140.4 total CFU m −3. When atmospheric temperature allowed use, the high-volume liquid impinger utilized in this study resulted in much higher
recoveries, as much as 10× greater in a number of the categories (bacterial, fungal, and total CFU). Together, these data
illustrated that (1) the high-volume liquid impinger is clearly superior to membrane filtration for aeromicrobiology studies
if start-up costs are not an issue and temperature permits use; (2) although membrane filtration is more cost friendly and
has a ‘typically’ wider operational range, its limits include loss of cell viability with increased sample time and issues
with effectively extracting nucleic acids for community-based analyses; (3) the ability to recover culturable microorganisms
is limited in ‘extreme’ atmospheric environments and thus the use of a ‘limited’ methodology in these environments must be
taken into account; and (4) the atmosphere culls, i.e., everything is not everywhere. 相似文献
13.
The impact of transgenic white poplars ( Populus alba L. cv. ‘Villafranca’) was assessed on the soil aerobic spore-forming bacteria (SFB). The genetically modified poplars, expressing
either the StSy gene for resveratrol production or the bar gene for herbicide tolerance, were cultivated in greenhouse. The occurrence of SFB was monitored in soil samples collected
at eight different timepoints over a two-year period. The total culturable bacterial population of the StSy and bar trials underwent significant seasonal fluctuations in the range of 10 6−2.5 × 10 8 CFU/g dry soil and of 10 4−5 × 10 8 CFU/g dry soil, respectively. Changes occurred also within the culturable SFB population with size varying at 10 3−5 × 10 4 CFU/g dry soil and 10 2−2 × 10 5 CFU/g dry soil in the StSy and bar trials, respectively. No significant differences in the size of the total and SFB culturable populations were observed when
comparing each transgenic line with the nontransformed control line while seasonal shifts of soil bacterial populations were
evident in both trials. The culturable SFB fraction included three isolates (SFB-1, SFB-2 and SFB-3) classified by 16S rDNA
sequence analysis as members of the Bacillus genus. According to the reported data, cultivation of both herbicide-resistant and resveratrol-producing GM white poplars
did not affect the culturable SFB population at the soil level. 相似文献
14.
In recent years, monitoring of airborne bacteria and fungi concentrations has obtained increasing universal attraction not only for influences on ecological balance but also for evaluating their public health consequences. In this study, we aimed to investigate culturable airborne bacteria and fungi levels in different sites of Abadan, and their association with meteorological parameters and PM2.5 levels. Abadan is one of the most industrialized cities in the southwest of Iran where over the current decade has experienced lots of dust storm episodes. In total, 400 air samples were collected in 6 months (autumn and winter) using a single-stage viable Andersen cascade impactor for sampling airborne bacteria and fungi and portable DustTrak Aerosol Monitor 8520 for measuring PM2.5 concentrations and meteorological parameters. Microbial concentrations showed a significant difference between various sites over the study period with averages of 569.57?±?312.64 and 482.73?±?242.86 CFU/M3 for bacteria and fungi, respectively. The air temperature had a significant effect on the concentration of both airborne bacteria and fungi. A significant positive correlation between relative humidity and fungi but no correlation between relative humidity and bacteria concentrations were observed. The average airborne PM2.5 concentrations of all sites among the study period was 93.24?±?116.72 μg/m3. The atmospheric bacterial and fungal communities were strongly positively correlated with the ambient PM2.5 level. The levels of airborne bacteria and fungi along with PM2.5 in the air of the city were relatively higher than the recommended levels. Therefore, the best course of action is needed to control emission sources. Further studies are also needed to evaluate the clinical analysis of the health effects of exposure to these pollutants. 相似文献
15.
This is the first study to quantify the dependence on wind velocity of airborne bacterial emission fluxes from soil. It demonstrates that manure bacteria get aerosolized from fertilized soil more easily than soil bacteria, and it applies bacterial genomic sequencing for the first time to trace environmental faecal contamination back to its source in the chicken barn. We report quantitative, airborne emission fluxes of bacteria during and following the fertilization of agricultural soil with manure from broiler chickens. During the fertilization process, the concentration of airborne bacteria culturable on blood agar medium increased more than 600 000-fold, and 1 m 3 of air carried 2.9 × 10 5 viable enterococci, i.e. indicators of faecal contamination which had been undetectable in background air samples. Trajectory modelling suggested that atmospheric residence times and dispersion pathways were dependent on the time of day at which fertilization was performed. Measurements in a wind tunnel indicated that airborne bacterial emission fluxes from freshly fertilized soil under local climatic conditions on average were 100-fold higher than a previous estimate of average emissions from land. Faecal bacteria collected from soil and dust up to seven weeks after fertilization could be traced to their origins in the poultry barn by genomic sequencing. Comparative analyses of 16S rRNA gene sequences from manure, soil and dust showed that manure bacteria got aerosolized preferably, likely due to their attachment to low-density manure particles. Our data show that fertilization with manure may cause substantial increases of bacterial emissions from agricultural land. After mechanical incorporation of manure into soil, however, the associated risk of airborne infection is low. 相似文献
16.
Inhalation of airborne microorganisms and organic dust is an occupational concern among workers in agricultural industries.
Airborne microorganisms and particulate matter samples were collected from poultry house, flourmill, textile, and food industry
sites by use of liquid impinger and gravimetric samplers. Particulate matter concentrations were recorded at median concentrations
of 1.56, 1.92, 4.39, and 0.7 mg/m 3 in the occupied poultry house, textile, flourmill, and food indoor working environments, respectively. The highest median
particulate matter concentration (27.9 mg/m 3) was detected at the flourmill’s stack site. The highest median indoor concentration of culturable airborne bacteria (6.23 × 10 5 CFU/m 3) was found at the occupied poultry-house site and the lowest concentration (4.6 × 10 3 CFU/m 3) was found at the food industry site. The highest median indoor concentration of culturable airborne fungi (3.15 × 10 4 CFU/m 3) was found at the flourmill site whereas the lowest (1.24 × 10 3 CFU/m 3) was found at the textile industry site. Bacillus and Staphylococcus were the predominant Gram-positive bacteria whereas Acinetobacter and Klebsiella were the predominant Gram-negative bacteria. Escherichia coli and Salmonella were only detected in the indoor air at the poultry house site. Aspergillus
flavus, Aspergillus niger, Penicillium, and yeast were the predominant fungal types at flourmill, textile, food industry, and poultry house, respectively. Workers
were continuously exposed to airborne microorganisms at a median value of 10 4 CFU/m 3 in all the industries studied. 相似文献
17.
The collection efficiency and sample retention of a batch-type wetted wall bioaerosol sampling cyclone (BWWC) were experimentally
characterized. The BWWC is designed to sample air at 400 l/min and concentrate the particles into 12 ml of water. Aerosol
is transported into a cylindrically-shaped axial flow cyclone through a tangential slot and the particles are impacted on
the inner wall, which is wetted by air shear acting on a liquid pool at the base of the cyclone. The retention of collected
particles and the aerosol collection efficiency of the BWWC were evaluated with polystyrene latex beads (PSL), sodium fluorescein/oleic
acid droplets, and Bacillus atrophaeus (aka BG) spores. The retention of particles was determined by adding hydrosol directly into the device, running the BWWC
for a pre-set period of time, and then determining the amount of particulate matter recovered relative to the initial amount.
For 1-μm diameter PSL, 90% of the particles were recoverable from the cyclone body immediately after their introduction; however,
only 10% were retained in the collection liquid after 8 h of operation. The aerosol sampling efficiency was determined by
comparing the amount of particulate matter collected in the liquid with that collected by a reference filter. The collection
efficiency was 50–60% for 1- and 3-μm polystyrene (PSL) particles, and 1.5% for 10-μm oleic acid particles. The efficiency
for 3-μm oleic acid droplets was 35%. Explanations are provided for the difference between liquid and solid particle behavior,
and for the low efficiency for the large liquid particles. The collection efficiency for single spore BG was slightly lower
than that for 1-μm PSL. 相似文献
18.
Indoor microbial exposure has been related to adverse pulmonary health effects. Exposure assessment is not standardized, and various factors may affect the measured exposure. The aim of this study was to investigate the seasonal variation of selected microbial exposures and their associations with temperature, relative humidity, and air exchange rates in Danish homes. Airborne inhalable dust was sampled in five Danish homes throughout the four seasons of 1 year (indoors, n = 127; outdoors, n = 37). Measurements included culturable fungi and bacteria, endotoxin, N-acetyl-beta- d-glucosaminidase, total inflammatory potential, particles (0.75 to 15 μm), temperature, relative humidity, and air exchange rates. Significant seasonal variation was found for all indoor microbial exposures, excluding endotoxin. Indoor fungi peaked in summer (median, 235 CFU/m 3) and were lowest in winter (median, 26 CFU/m 3). Indoor bacteria peaked in spring (median, 2,165 CFU/m 3) and were lowest in summer (median, 240 CFU/m 3). Concentrations of fungi were predominately higher outdoors than indoors, whereas bacteria, endotoxin, and inhalable dust concentrations were highest indoors. Bacteria and endotoxin correlated with the mass of inhalable dust and number of particles. Temperature and air exchange rates were positively associated with fungi and N-acetyl-beta- d-glucosaminidase and negatively with bacteria and the total inflammatory potential. Although temperature, relative humidity, and air exchange rates were significantly associated with several indoor microbial exposures, they could not fully explain the observed seasonal variations when tested in a mixed statistical model. In conclusion, the season significantly affects indoor microbial exposures, which are influenced by temperature, relative humidity, and air exchange rates. 相似文献
19.
Bacterial air sampling in an animal care laboratory showed that dense aerosols are generated during cage changing and cage cleaning. Reyniers and Andersen sampling showed that the airborne bacteria numbered 50 to 200 colony-forming units (CFU)/ft 3 of air. Of the viable particles collected by Andersen samplers, 78.5% were larger than 5.5 μm. A low velocity laminar air flow system composed of high-efficiency particulate air (HEPA) filters and a ceiling distribution system maintained the number of airborne viable particles at low levels, generally less than 2 CFU/ft 3. Vertical air flow of 15 ft/min significantly reduced the rate of airborne infection by a strain of Proteus mirabilis. Other factors shown to influence airborne infection included type of cage utilized, the use of bedding, the distance between cages, and the number of animals per cage. 相似文献
20.
The Coriolis δ air sampler manufactured by Bertin Technologies (France) is a continuous air sampler, dedicated to outdoor monitoring of
airborne spores and pollen grains. This high-volume sampler is based on patented Coriolis technology delivering a liquid sample.
The air is drawn into a conical vial in a whirling type motion using suction; particles are pulled against the wall by centrifugal
force. Airborne particles are separated from the air and collected in a liquid medium. This innovative solution allows rapid
analysis by several techniques including PCR assay and serological assay in order to measure the antigenicity/allergenicity
of pollen grains and fungal spores. Also, traditional counting of pollen grains or taxa identification by optical microscopy
can be done. A study has been carried out by the Health Protection Agency (HPA), Porton Down, UK, to measure the physical
efficiency of the Coriolis air sampler. The physical efficiency of the sampler for collection of micro-organism-laden particles
of various sizes has been compared with that of membrane filter samplers using the techniques described by ISO 14698-1. The
Coriolis was operated simultaneously with membrane filter samplers in a controlled room where they were challenged with uniform-sized
particles of different diameters containing bacterial spores. For the larger particle sizes, it was found that the physical
efficiency of the Coriolis was 92% for 10-μm particles. The biological performance of the Coriolis in the collection of airborne
fungal spores and pollen grains was evaluated in comparison with a Hirst spore trap (one-week tape-on-drum type sampler) which
is one of the most frequently used traps in the measurement of outdoor pollen grain concentrations. The advantages and limitations
of both technologies are discussed. The Coriolis was operated simultaneously with a Hirst spore trap in the sampling station
of Réseau National de Surveillance Aérobiologique, France (RNSA); the pollen grain and fungal spore counts were analysed by
optical microscopy. The pollen grain count m −3 collected was compared for both devices. The dispersion values were obtained and statistical analysis was carried out. This
study shows that the Coriolis air sampler provided equivalent recovery of pollen grain and fungal spores compared with the
volumetric trap standard method (not significantly different, W test, α = 0.05). Nowadays, the French-led project, acronym MONALISA, with financial support from the European Commission––Life-Environment
(LIFE05 ENV/F/000068), is testing this innovative air sampler in order to measure the antigenicity/allergenicity of the main
aeroallergen particles, i.e. Betula (birch), Poaceae (grasses), Parietaria (pellitory), Olea spp (olive tree), and Artemisia (mugwort) pollen grains, and Alternaria (fungal spores) to validate a new approach of monitoring instead of quantifying pollen grains by their morphology. The robustness
and efficiency of the MONALISA system is being demonstrated at a national level throughout Europe in eight different countries
with different bio-climatic and topography characteristics: France, UK, Finland, Poland, Spain, Portugal, Switzerland, and
Italy. 相似文献
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