Showing papers on "Bioaerosol published in 2015"

Chamber Bioaerosol Study: Outdoor Air and Human Occupants as Sources of Indoor Airborne Microbes

Abstract: Human occupants are an important source of microbes in indoor environments. In this study, we used DNA sequencing of filter samples to assess the fungal and bacterial composition of air in an environmental chamber under different levels of occupancy, activity, and exposed or covered carpeting. In this office-like, mechanically ventilated environment, results showed a strong influence of outdoor-derived particles, with the indoor microbial composition tracking that of outdoor air for the 2-hour sampling periods. The number of occupants and their activity played a significant but smaller role influencing the composition of indoor bioaerosols. Human-associated taxa were observed but were not particularly abundant, except in the case of one fungus that appeared to be transported into the chamber on the clothing of a study participant. Overall, this study revealed a smaller signature of human body-associated taxa than had been expected based on recent studies of indoor microbiomes, suggesting that occupants may not exert a strong influence on bioaerosol microbial composition in a space that, like many offices, is well ventilated with air that is moderately filtered and moderately occupied.

Detection and characterization of biological and other organic-carbon aerosol particles in atmosphere using fluorescence

Abstract: This paper offers a brief review on the detection and characterization of biological and other organic-carbon (OC) aerosol particles in atmosphere using laser-induced-fluorescence (LIF) signatures. It focuses on single individual particles or aggregates in the micron and super-micron size range when they are successively drawn through the interrogation volume of a point detection system. Related technologies for these systems that have been developed in last two decades are also discussed. These results should provide a complementary view for studying atmospheric aerosol particles, particularly bioaerosol and OC aerosol particles from other analytical technologies.

Assessment of bioaerosol contamination (bacteria and fungi) in the largest urban wastewater treatment plant in the Middle East

Abstract: Bioaerosol concentration was measured in wastewater treatment units in south of Tehran, the largest wastewater treatment plant in the Middle East. Active sampling was carried out around four operational units and a point as background. The results showed that the aeration tank with an average of 1016 CFU/m3 in winter and 1973 CFU/m3 in summer had the greatest effect on emission of bacterial bioaerosols. In addition, primary treatment had the highest impact on fungal emission. Among the bacteria, Micrococcus spp. showed the widest emission in the winter, and Bacillus spp. was dominant in summer. Furthermore, fungi such as Penicillium spp. and Cladosporium spp. were the dominant types in the seasons. Overall, significant relationship was observed between meteorological parameters and the concentration of bacterial and fungal aerosols.

Airborne observations of regional variation in fluorescent aerosol across the United States

Abstract: Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wideband of longitude across the continental U.S. between Florida and California and between 28 and 37-N latitudes. Sampling occurred from near the surface to 1000-m above the ground. A Wideband Integrated Bioaerosol Sensor (WIBS-4) measured average concentrations of supermicron fluorescent particles aloft (1-μm to 10-μm), revealing number concentrations ranging from 2.1-±-0.8 to 8.7-±-2.2-×-104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol. Fluorescent aerosol detected in the east is largely consistent with mold spores observed in a laboratory setting, while a shift to larger sizes associated with different fluorescent patterns is observed in the west. Fluorescent bioaerosol loadings in the desert west were as high as those near the Gulf of Mexico, suggesting that bioaerosol is a substantial component of supermicron aerosol both in humid and arid environments. The observations are compared to model fungal and bacterial loading predictions, and good agreement in both particle size and concentrations is observed in the east. In the west, the model underestimated observed concentrations by a factor between 2 and 4 and the prescribed particle sizes are smaller than the observed fluorescent aerosol. A classification scheme for use with WIBS data is also presented. Key Points Fluorescent supermicron aerosol loads are reported across the southern U.S. Regional variations in fluorescent behavior and particle size are observed Comparison to modeled emissions shows an underestimate in the west

Emission and Dispersion of Bioaerosols from Dairy Manure Application Sites: Human Health Risk Assessment

Abstract: In this study, we report the human health risk of gastrointestinal infection associated with inhalation exposure to airborne zoonotic pathogens emitted following application of dairy cattle manure to land. Inverse dispersion modeling with the USEPA’s AERMOD dispersion model was used to determine bioaerosol emission rates based on edge-of-field bioaerosol and source material samples analyzed by real-time quantitative polymerase chain reaction (qPCR). Bioaerosol emissions and transport simulated with AERMOD, previously reported viable manure pathogen contents, relevant exposure pathways, and pathogen-specific dose-response relationships were then used to estimate potential downwind risks with a quantitative microbial risk assessment (QMRA) approach. Median 8-h infection risks decreased exponentially with distance from a median of 1:2700 at edge-of-field to 1:13 000 at 100 m and 1:200 000 at 1000 m; peak risks were considerably greater (1:33, 1:170, and 1:2500, respectively). These results indicate that bioa...

Indoor/outdoor relationships of bioaerosol concentrations in a retirement home and a school dormitory

Abstract: The concentrations of bacterial and fungal bioaerosols were measured in a retirement home and a school dormitory from May 2012 to May 2013. In the present work, two active and passive methods were used for bioaerosol sampling. The results from the present work indicated that Bacillus spp., Micrococcus spp., and Staphylococcus spp. were the dominant bacterial genera, while the major fungal genera were Penicillium spp., Cladosporium spp., and Aspergillus spp. The results also indicated that the indoor-to-outdoor (I/O) ratios for total bacteria were 1.77 and 1.44 in the retirement home and the school dormitory, respectively; the corresponding values for total fungal spores were 1.23 and 1.08. The results suggested that in addition to outdoor sources, indoor sources also played a significant role in emitting bacterial and fungal bioaerosols in the retirement home and the school dormitory indoor.

Protocol Improvements for Low Concentration DNA-Based Bioaerosol Sampling and Analysis.

Abstract: Introduction As bioaerosol research attracts increasing attention, there is a need for additional efforts that focus on method development to deal with different environmental samples. Bioaerosol environmental samples typically have very low biomass concentrations in the air, which often leaves researchers with limited options in choosing the downstream analysis steps, especially when culture-independent methods are intended. Objectives This study investigates the impacts of three important factors that can influence the performance of culture-independent DNA-based analysis in dealing with bioaerosol environmental samples engaged in this study. The factors are: 1) enhanced high temperature sonication during DNA extraction; 2) effect of sampling duration on DNA recoverability; and 3) an alternative method for concentrating composite samples. In this study, DNA extracted from samples was analysed using the Qubit fluorometer (for direct total DNA measurement) and quantitative polymerase chain reaction (qPCR). Results and Findings The findings suggest that additional lysis from high temperature sonication is crucial: DNA yields from both high and low biomass samples increased up to 600% when the protocol included 30-min sonication at 65°C. Long air sampling duration on a filter media was shown to have a negative impact on DNA recoverability with up to 98% of DNA lost over a 20-h sampling period. Pooling DNA from separate samples during extraction was proven to be feasible with margins of error below 30%.

Concentration and size distribution of viable bioaerosols during non-haze and haze days in Beijing

Abstract: Accumulation of airborne particulate matter (PM) has profoundly affected the atmospheric environment of Beijing, China. Although studies on health risks have increased, characterization of specific factors that contribute to increased health risks remains an area of needed exploration. Chemical composition studies on PM can readily be found in the literature but researches on biological composition are still limited. In this study, the concentration and size distribution of viable airborne bacteria and fungi were determined in the atmosphere from May to July 2013 in Beijing, China. Samples were collected during non-haze days and haze days based on the value of air quality index (AQI) PM2.5. Multiple linear regression results indicated that concentrations of viable bioaerosol exhibited a negative correlation with PM2.5 (AQI) ranging from 14 to 452. There was a little difference in size distribution of bioaerosol between non-haze and haze days that all airborne bacteria showed skewed trends toward larger sizes and airborne fungi followed a Gaussian distribution. Spearman's correlation analysis showed that a fraction of bioaerosol with fine and coarse particles had negative and positive relations with PM2.5 (AQI), respectively. Moreover, the temporal variation of d g (aerodynamic diameter) of bioaerosol with PM2.5 (AQI) fluctuated from 9:00 to 21:00, which suggested that their deposition pattern would vary during a day. The primary research in this study implied that aerodynamic size variation should be considered in assessing the bioaerosol exposure during haze weather.

Field Evaluation of Personal Sampling Methods for Multiple Bioaerosols

Abstract: Ambient bioaerosols are ubiquitous in the daily environment and can affect health in various ways. However, few studies have been conducted to comprehensively evaluate personal bioaerosol exposure in occupational and indoor environments because of the complex composition of bioaerosols and the lack of standardized sampling/analysis methods. We conducted a study to determine the most efficient collection/analysis method for the personal exposure assessment of multiple bioaerosols. The sampling efficiencies of three filters and four samplers were compared. According to our results, polycarbonate (PC) filters had the highest relative efficiency, particularly for bacteria. Side-by-side sampling was conducted to evaluate the three filter samplers (with PC filters) and the NIOSH Personal Bioaerosol Cyclone Sampler. According to the results, the Button Aerosol Sampler and the IOM Inhalable Dust Sampler had the highest relative efficiencies for fungi and bacteria, followed by the NIOSH sampler. Personal sampling was performed in a pig farm to assess occupational bioaerosol exposure and to evaluate the sampling/analysis methods. The Button and IOM samplers yielded a similar performance for personal bioaerosol sampling at the pig farm. However, the Button sampler is more likely to be clogged at high airborne dust concentrations because of its higher flow rate (4 L/min). Therefore, the IOM sampler is a more appropriate choice for performing personal sampling in environments with high dust levels. In summary, the Button and IOM samplers with PC filters are efficient sampling/analysis methods for the personal exposure assessment of multiple bioaerosols.

Quantitative microbial risk assessment of bioaerosols from a manure application site

Abstract: Bioaerosol concentrations and deposition were monitored at the edge of a dairy manure application site in northern New York State. Total bacteria, fecal indicator bacteria (Enterococcus spp. and Escherichia coli), and select bacterial pathogens (Salmonella spp., Campylobacter spp., and E. coli O157:H7) were measured in the manure and air by real-time quantitative PCR (qPCR). The 8-h average bacterial air concentration measured by liquid impingement following manure application was 7.89 × 105 copies m−3, one order of magnitude greater than mean background measurements (6.35 × 104 copies m−3; n = 6). Eight-hour ambient concentration of Enterococcus spp. was 1.54 × 104 copies m−3; E. coli and pathogens were less than their respective limits of detection. The measured deposition flux of bacteria was 1.08 × 103 copies m−2 s−1, corresponding to bulk deposition velocity of 0.15 cm s−1. Using inverse dispersion modeling with the US Environmental Protection Agency’s AERMOD, the emission of bacteria from the manure-amended field was estimated to be 1.27 × 105 copies m−2 s−1. AERMOD was also used to model downwind bioaerosol concentrations; the greatest modeled 8-h average downwind bacteria concentrations were 8.00 × 105 copies m−3 above background at 100 m and 3.95 × 103 copies m−3 above background at 1,000 m. Potential health risks associated with these bioaerosols were estimated by quantitative microbial risk assessment based on AERMOD results using measured pathogen concentrations in land-applied manure and emission rate estimates for total bacteria. Median risks of infection over an 8-h exposure period were 1:500 at 100 m and 1:100,000 at 1,000 m; peak risks (95th percentile) were 1:250 and 1:50,000, respectively.

Characterization of Ambient PM10 Bioaerosols in a California Agricultural Town

Abstract: Ambient bioaerosols in PM10 samples were measured at three sites in Corcoran, an agricultural town in the southern San Joaquin Valley (SJV) of California, during fall of 2000 corresponding to the cotton harvest season. Elevated bioaerosol concentrations were measured near grain elevators (GRA site) and a cotton handling facility (BAI site) as compared to levels in a residential community (COP site), ~2 km northeast of these sources. Average endotoxin levels (13 ± 17 EU/m3) at the grain elevator site were three to eight times higher than averages at the nearby cotton-handling and residential sites. The highest level (47.6 EU/m3) at the grain elevator site was about half of the exposure limit of 90 EU/m3 set by the Dutch Expert Committee on Occupational Safety. Particle counts of fungal spore (66,333 particles/m3) and pollen grain (2,600 particles/m3) concentrations were more than double those reported in the literature. Average fungal biomarker concentrations of 170 and 131 ng/m3 for arabitol and mannitol, respectively, were 1–2 orders of magnitude higher than those from non-agricultural areas. The low correlation (r < 0.11) of three fungal markers (i.e., (1→3)-β-D-glucan, arabitol, and mannitol) with fungi counts is consistent with findings by others and indicates that these are insufficient as surrogates to represent fungal exposure. Agricultural activities contributed measureable amounts to PM10 mass and organic carbon (OC), dominated by fungal spores (i.e., 5.4–5.8% PM10 mass and 11.5–14.7% OC). The sum of fungal spores, pollen grains, and plant detritus accounted for an average of 11–15% PM10 and 24–33% OC mass. Bioaerosols can be important contributors to PM10 mass in farming communities similar to Corcoran, especially during intense agricultural activities.

Microbial aerosol characteristics in highly polluted and near-pristine environments featuring different climatic conditions

Abstract: There is an increasing interest in understanding ambient bioaerosols due to their roles both in health and in climate. Here, we deployed an Ultraviolet Aerodynamic Particle Sizer to monitor viable (fluorescent) bioaerosol concentration levels at city centers (highly polluted) and their corresponding suburbs (near pristine) (total 40 locations) in 11 provinces featuring different climate zones in China between July 16 and 28, 2013. The concentration levels of viable bioaerosol particles (BioPM) of >0.5 µm were measured, and corresponding percentages of BioPM% (biological fraction of total PM) and BioPM2.5% (biological fraction of PM2.5) in particulate matter (PM) and BioPM, respectively, were determined. For some key cities, indoor viable bioaerosol levels were also obtained. In addition, bacterial structures of the air samples collected across these monitoring locations were studied using pyrosequencing. BioPM concentration levels ranged from 2.1 × 104 to 2.4 × 105/m3 for city centers [BioPM% = 6.4 % (±6.3 %)] and 0.5 × 104 to 4.7 × 105/m3 for suburbs [BioPM% = 10 % (±8.7 %)]. Distinctive bioaerosol size distribution patterns were observed for different climate zones, e.g., some had fluorescence peaks at 3 µm, while the majority had peaks at 1 µm. Ambient bacterial aerosol community structures were also found different for different geophysical locations. Results suggest that there was a poor overall relationship between PM and BioPM across 40 monitoring locations (R2 = 0.081, two-tailed P value = 0.07435). Generally, city centers had higher PM concentrations than suburbs, but not BioPM and BioPM%. Indoor bioaerosol levels were found at least tenfold higher than those corresponding outdoors. Bacillus was observed to dominate the bacterial aerosol community in the air sample.

Continuous aerosol size separator using inertial microfluidics and its application to airborne bacteria and viruses.

Abstract: A microchannel-based aerosol size separator that separates submicron aerosols according to particle inertial differences and Dean vortices in the airflow was developed for use in low-cost, portable, real-time aerosol collectors, detectors, concentrators and other such devices. The microfluidic inertial separator was furthermore applied to simultaneously separate airborne microorganisms by size, such as airborne viruses and bacteria from larger aerosols and viral particles from bacterial cells. The entire system was designed by numerical simulation and analysis. In addition, its performance was evaluated experimentally using airborne standard polystyrene latex (PSL) particles. In addition, two airborne microorganisms, Adenovirus 40 and Staphylococcus epidermidis, were used to verify the performance of the separator. The separation ratios of each bioaerosol were measured using real-time aerosol measurement instruments and quantitative polymerase chain reaction (qPCR) analysis. The system was composed of two 90° curved microchannels and three outlets for separating the virus, bacteria and larger particles. About 70% of 3 μm particles but almost none of the bioaerosols were separated out at the first outlet. In addition, more than 70% of S. epidermidis and ~70% Adenovirus were separated out at the second and third outlets, respectively. Unwanted particle loss in the system was less than 10%. The results indicated not only good separation of bioaerosols but also the potential of our separator for use in bioaerosol applications.

Microbial aerosol liberation from soiled textiles isolated during routine residuals handling in a modern health care setting

Abstract: A wide variety of specialty textiles are used in health care settings for bedding, clothing, and privacy. The ability of textiles to host or otherwise sequester microbes has been well documented; however, their reciprocal potential for liberating airborne bacteria remains poorly characterized. In response, a multi-season survey of bacterial bioaerosols was conducted in the origin and terminus of residual paths which are specifically designed to isolate soiled hospital textiles as they are moved to laundering. This survey used conventional optical particle counting which incorporated multi-channel fluorescence in conjunction with molecular phylogenetic analyses to characterize the bioaerosols liberated during soiled textile storage—immediately before and after the occupation of a modern hospital. Although outfitted with a HEPA filtration system, the number of airborne particles presenting fluorescing optical signatures consistent with airborne bacteria and fungi significantly increased in textile holding rooms soon after the hospital’s commissioning, even though these isolated residual areas rarely host personnel. The bioaerosol liberated during textile storage was characterized using Illumina MiSeq sequencing of bacterial 16S ribosomal ribonucleic acid (rRNA) genes. Gene copies recovered by quantitative PCR from aerosol collected in co-located impingers were consistent with fluorescence gated optical particle counting. The relative abundance patterns of proximal bacterial bioaerosol were such that the air in the origin and terminus of textile storage rooms could not be differentiated once the hospital began processing soiled linens. Genes from microbes typically associating with human skin, feces, and hair—Staphylococcus, Propionibacteria, Corynebacteria, Lactobacillus, and Streptococcus spp.—dominated the aerosol abundance profiles in textile holding rooms, which were generally far less diverse than communities recovered from surfaces in patient rooms. These results suggest that aerosol partitioning from the routine handling of soiled textiles can contribute to airborne exposures in the health care environment.

Assessment of microbial contamination within working environments of different types of composting plants.

Abstract: The objective of the study was to determine the degree of microbiological contamination, type of microflora, bioaerosol particle size distribution, and concentration of endotoxins in dust in different types of composting plants. In addition, this study provides a list of indicator microorganisms that pose a biological threat in composting facilities, based on their prevalence within the workplace, source of isolation, and health hazards. We undertook microbiological analysis of the air, work surfaces, and compost, and assessed the particle size distribution of bioaerosols using a six-stage Andersen sampler. Endotoxins were determined using gas chromatography–mass spectrometry (GC-MS). Microbial identification was undertaken both microscopically and using biochemical tests. The predominant bacterial and fungal species were identified using 16S rRNA and ITS1/2 analysis, respectively. The number of mesophilic microorganisms in composting plants amounted to 6.9 × 102–2.5 × 104 CFU/m3 in the air, 2.9 × 102–3.3...

Integrated micro-optofluidic platform for real-time detection of airborne microorganisms

Abstract: We demonstrate an integrated micro-optofluidic platform for real-time, continuous detection and quantification of airborne microorganisms. Measurements of the fluorescence and light scattering from single particles in a microfluidic channel are used to determine the total particle number concentration and the microorganism number concentration in real-time. The system performance is examined by evaluating standard particle measurements with various sample flow rates and the ratios of fluorescent to non-fluorescent particles. To apply this method to real-time detection of airborne microorganisms, airborne Escherichia coli, Bacillus subtilis, and Staphylococcus epidermidis cells were introduced into the micro-optofluidic platform via bioaerosol generation, and a liquid-type particle collection setup was used. We demonstrate successful discrimination of SYTO82-dyed fluorescent bacterial cells from other residue particles in a continuous and real-time manner. In comparison with traditional microscopy cell counting and colony culture methods, this micro-optofluidic platform is not only more accurate in terms of the detection efficiency for airborne microorganisms but it also provides additional information on the total particle number concentration.

Fast Monitoring of Indoor Bioaerosol Concentrations with ATP Bioluminescence Assay Using an Electrostatic Rod-Type Sampler

Abstract: A culture-based colony counting method is the most widely used analytical technique for monitoring bioaerosols in both indoor and outdoor environments. However, this method requires several days for colony formation. In this study, our goal was fast monitoring (Sampling: 3 min, Detection: < 1 min) of indoor bioaerosol concentrations with ATP bioluminescence assay using a bioaerosol sampler. For this purpose, a novel hand-held electrostatic rod-type sampler (110 mm wide, 115 mm long, and 200 mm tall) was developed and used with a commercial luminometer, which employs the Adenosine triphosphate (ATP) bioluminescence method. The sampler consisted of a wire-rod type charger and a cylindrical collector, and was operated with an applied voltage of 4.5 kV and a sampling flow rate of 150.7 lpm. Its performance was tested using Staphylococcus epidermidis which was aerosolized with an atomizer. Bioaerosol concentrations were measured using ATP bioluminescence method with our sampler and compared with the culture-based method using Andersen cascade impactor under controlled laboratory conditions. Indoor bioaerosol concentrations were also measured using both methods in various indoor environments. A linear correlation was obtained between both methods in lab-tests and field-tests. Our proposed sampler with ATP bioluminescence method may be effective for fast monitoring of indoor bioaerosol concentrations.

Exposure to culturable and total microbiota in cultural heritage conservation laboratories.

Abstract: OBJECTIVES To date, the scientific source materials usually focus on microbial contamination of the museum or library collections themselves, while the exposure of persons who professionally deal with this type of objects in cultural heritage conservation laboratories is ignored. MATERIAL AND METHODS The study was carried out in 9 naturally ventilated conservation laboratories with no history of water damage. Viable (understood as culturable) bioaerosol stationary samples were collected in both outdoor and indoor environments using 6-stage Andersen impactor. Simultaneously, stationary and personal indoor bioaerosol measurements were carried out using both Gesamtstaubprobenahme an der Person (GSP) and Button filter samplers. These measurements were complemented by evaluation of microbial content in the dust settled on conserved works of art. All impactor, filter, and settled dust samples were quantitatively examined to obtain viable and total concentrations of bacteria and fungi. All isolated microbial strains were taxonomically identified. RESULTS At workplaces, the concentrations of viable microorganisms in air were below 2000 cfu/m3 and accounted for not more than 5.5% of total microbiota. The study showed that quantitative assessment of viable bioaerosol can be made with an Andersen impactor as well as by using Button and GSP filter samplers, irrespective of whether they are applied for personal or stationary measurements. Compared to the impactor, however, the use of filter samplers for microbial contamination monitoring substantially limits the scope of qualitative information which can be obtained. Size distribution analysis revealed that the largest "load" of microorganisms can penetrate into the respiratory tract between the trachea and terminal bronchi, and thereby may be responsible for allergic inflammations in exposed workers. CONCLUSIONS The precise assessment of microbial hazards in conservation laboratories should comprise control of both viable and total particle counts. The hermetization of such workplaces and control of relative humidity should be implemented and maintained to assure proper hygienic conditions.

Effects of fungal species, cultivation time, growth substrate, and air exposure velocity on the fluorescence properties of airborne fungal spores.

Abstract: Real-time bioaerosol monitoring is possible with fluorescence based instruments. This study provides information on major factors that can affect the fluorescence properties of airborne fungal spores. Two fluorescence-based bioaerosol detectors, BioScout, and ultraviolet aerodynamic particle sizer (UVAPS), were used to study fluorescent particle fractions (FPFs) of released spores of three fungal species (Aspergillus versicolor, Cladosporium cladosporioides, and Penicillium brevicompactum). Two culture media (agar and gypsum board), three ages of the culture (one week, one month, and four months), and three aerosolization air velocities (5, 15, and 27 m/s) were tested. The results showed that the FPF values for spores released from gypsum were typically lower than for those released from agar indicating that poor nutrient substrate produces spores with lower amounts of fluorescent compounds. The results also showed higher FPF values with lower air velocities in aerosolization. This indicates that easily released fully developed spores have more fluorescent compounds compared to forcibly extracted non-matured spores. The FPFs typically were lower with older samples. The FPF results between the two instruments were similar, except with four-month-old samples. The results can be utilized in field measurements of fungal spores to estimate actual concentrations and compare different instruments with fluorescence-based devices as well as in instrument calibration and testing in laboratory conditions.

Evaluation of bioaerosol exposures during hospital bronchoscopy examinations

Abstract: During hospital bronchoscopy examinations, aerosols emitted from the patient's during coughing can be found suspended in the ambient air. The aerosols can contain pathogenic microorganisms. Depending on their size, these microorganisms can remain in the air for a long time. The objective of this study was to measure the sizes and concentrations of the biological and non-biological particles produced during bronchoscopy examinations, and to propose preventive or corrective measures. Two bronchoscopy rooms were studied. An aerodynamic particle sizer (UV-APS) was used to establish the concentrations of the particles present and their size distributions. This instrument determines the aerodynamic diameter of the aerosols and can distinguish fluorescent (bioaerosols) and non-fluorescent particles. Reference concentrations were measured before the start of the examinations (morning background concentrations). They were used as comparison levels for the concentrations measured during and at the end of the bronchoscopies. In parallel, computational fluid dynamics (CFD) made it possible to isolate and understand different factors that can affect the concentration levels in bronchoscopy rooms. The concentrations of the non-fluorescent and fluorescent particles (bioaerosols) were significantly higher ( p ≤ 0.05) during the bronchoscopy examinations than the reference concentrations. For the investigated factors, the bioaerosol concentrations were significantly higher during bronchoscope insertion tasks. The time required at the end of the day for the bioaerosols to reach the morning reference concentrations was about fifteen minutes. The average particle sizes were 2.9 μm for the fluorescent particles (bioaerosols) and 0.9 μm for the non-fluorescent particles. Our models based on computational fluid dynamics (CFD) enabled us to observe the behaviour of aerosols for the different rooms.

Design and Evaluation of the Field-Deployable Electrostatic Precipitator with Superhydrophobic Surface (FDEPSS) with High Concentration Rate

Abstract: Here we report on further development of an electrostatics-based bioaerosol collector with high concentration rate. We developed a field-deployable version of the electrostatic precipitator with superhydrophobic surface (FDEPSS), which consists of two combined half-cylinder collection chambers and an integrated control box. The collector is made of a static dissipative material and each collection chamber features a 3.2 mm wide collection electrode. The round top part of each chamber contains eight carbon fiber ionizers arranged in two lines of four. The collected particles are removed by a 20 µL rolling water droplet. Sampler’s components were integrated into a control box. The FDEPSS was tested with two bacterial species, Bacillus atropheus and Pseudomonas fluorescens bacteria, and one fungal spore, Penicillium chrysogenum for 10 and 60 min collection times and showed collection efficiency of ~70% at a sampling flow rate of 20 L min–1. The use of a collecting water droplet of 20 µL per collection chamber achieved sample concentration rates approaching 0.5 × 106 min–1. The FDEPSS was also tested against BioSampler (SKC Inc., Eighty Four, PA) and Button aerosol sampler (SKC Inc.) when sampling bioaerosols outdoors for 60 min. The samples were characterized based on the total airborne adenosine triphosphate (ATP) concentration, which was reported as relative luminescence units (RLU). The FDEPSS detected 5.1 × 105 RLU m–3, while the BioSampler and the Button sampler showed 4.1 × 105 RLU m–3 and 8.7 × 105 RLU m–3, respectively. Since ATP analysis can be performed with small sample volumes, and the FDEPSS captures particles into 20 µL of liquid, resulting in a high concentration rate, we show that this sampler can detect the presence of airborne microorganisms 40× faster than the BioSampler or Button aerosol sampler. This FDEPSS feature could be integrated into bioaerosol detection systems, especially where concentrations are low and time is critical.