Showing papers on "Bioaerosol published in 2010"

Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS) in Central Europe

Abstract: . Primary Biological Aerosol Particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure Fluorescent Biological Aerosol Particles (FBAPs), which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles ( Averaged over the four-month measurement period (August–December 2006), the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h) with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical analyses of PBAPs in aerosol filter samples. To our knowledge, however, this is the first exploratory study reporting continuous online measurements of bioaerosol particles over several months and a range of characteristic size distribution patterns with a persistent bioaerosol peak at ~3 μm. The measurement results confirm that PBAPs account for a substantial proportion of coarse aerosol particle number and mass in continental boundary layer air. Moreover, they suggest that the number concentration of viable bioparticles is dominated by fungal spores or agglomerated bacteria with aerodynamic diameters around 3 μm rather than single bacterial cells with diameters around 1 μm.

Accuracy, Precision, and Method Detection Limits of Quantitative PCR for Airborne Bacteria and Fungi

Abstract: Real-time quantitative PCR (qPCR) for rapid and specific enumeration of microbial agents is finding increased use in aerosol science. The goal of this study was to determine qPCR accuracy, precision, and method detection limits (MDLs) within the context of indoor and ambient aerosol samples. Escherichia coli and Bacillus atrophaeus vegetative bacterial cells and Aspergillus fumigatus fungal spores loaded onto aerosol filters were considered. Efficiencies associated with recovery of DNA from aerosol filters were low, and excluding these efficiencies in quantitative analysis led to underestimating the true aerosol concentration by 10 to 24 times. Precision near detection limits ranged from a 28% to 79% coefficient of variation (COV) for the three test organisms, and the majority of this variation was due to instrument repeatability. Depending on the organism and sampling filter material, precision results suggest that qPCR is useful for determining dissimilarity between two samples only if the true differences are greater than 1.3 to 3.2 times (95% confidence level at n = 7 replicates). For MDLs, qPCR was able to produce a positive response with 99% confidence from the DNA of five B. atrophaeus cells and less than one A. fumigatus spore. Overall MDL values that included sample processing efficiencies ranged from 2,000 to 3,000 B. atrophaeus cells per filter and 10 to 25 A. fumigatus spores per filter. Applying the concepts of accuracy, precision, and MDL to qPCR aerosol measurements demonstrates that sample processing efficiencies must be accounted for in order to accurately estimate bioaerosol exposure, provides guidance on the necessary statistical rigor required to understand significant differences among separate aerosol samples, and prevents undetected (i.e., nonquantifiable) values for true aerosol concentrations that may be significant.

BOARD-INVITED REVIEW: Fate and transport of bioaerosols associated with livestock operations and manures

Abstract: Airborne microorganisms and microbial by-products from intensive livestock and manure management systems are a potential health risk to workers and individuals in nearby communities. This report presents information on zoonotic pathogens in animal wastes and the generation, fate, and transport of bioaerosols associated with animal feeding operations and land applied manures. Though many bioaerosol studies have been conducted at animal production facilities, few have investigated the transport of bioaerosols during the land application of animal manures. As communities in rural areas converge with land application sites, concerns over bioaerosol exposure will certainly increase. Although most studies at animal operations and wastewater spray irrigation sites suggest a decreased risk of bioaerosol exposure with increasing distance from the source, many challenges remain in evaluating the health effects of aerosolized pathogens and allergens in outdoor environments. To improve our ability to understand the off-site transport and diffusion of human and livestock diseases, various dispersion models have been utilized. Most studies investigating the transport of bioaerosols during land application events have used a modified Gaussian plume model. Because of the disparity among collection and analytical techniques utilized in outdoor studies, it is often difficult to evaluate health effects associated with aerosolized pathogens and allergens. Invaluable improvements in assessing the health effects from intensive livestock practices could be made if standardized bioaerosol collection and analytical techniques, as well as the use of specific target microorganisms, were adopted.

Assessment of Bacterial and Fungal Aerosol in Different Residential Settings

Abstract: The concentration and size distribution of bacterial and fungal aerosol was studied in 15 houses. The houses were categorized into three types, based on occupant density and number of rooms: single room in shared accommodation (type I), single bedroom flat in three storey buildings (type II) and two or three bedroomed houses (type III). Sampling was undertaken with an Anderson six-stage impactor during the summer of 2007 in the living rooms of all the residential settings. The maximum mean geometric concentration of bacterial (5,036 CFU/m3, ± 2.5, n = 5) and fungal (2,124 CFU/m3, ± 1.38, n = 5) aerosol were in housing type III. The minimum levels of indoor culturable bacteria (1,557 CFU/m3, ±1.5, n = 5) and fungal (925 CFU/m3, ±2.9, n = 5) spores were observed in housing type I. The differences in terms of total bacterial and fungal concentration were less obvious between housing types I and II as compared to type III. With reference to size distribution, the dominant stages for culturable bacteria in housing types I, II and III were stage 3 (3.3–4.7 μm), stage 1 (7 μm and above) and stage 5 (1.1–2.1 μm), respectively. Whereas the maximum numbers of culturable fungal spores were recovered from stage 2 (4.7–7 µm), in housing type I, and from stage 4 (2.1–3.3 μm) in both type II and III houses. The average geometric mean diameter of bacterial aerosol was largest in type I (4.7 μm), followed by type II (3.89 μm) and III (1.96 μm). Similarly, for fungal spores, type I houses had the highest average mean geometric diameter (4.5 μm), while in types II and III the mean geometric diameter was 3.57 and 3.92 μm, respectively. The results indicate a wide variation in total concentration and size of bioaerosols among different residential settings. The observed differences in the size distributions and concentrations reflect their variable airborne behaviour and, as a result, different risks of respiratory exposure of the occupants to bioaerosols in various residential settings.

A pilot study of bioaerosol reduction using an air cleaning system during dental procedures

Abstract: Background Bioaerosols are defined as airborne particles of liquid or volatile compounds that contain living organisms or have been released from living organisms. The creation of bioaerosols is a recognized consequence of certain types of dental treatment and represents a potential mechanism for the spread of infection. Objectives The aims of the present study were to assess the bioaerosols generated by certain dental procedures and to evaluate the efficiency of a commercially available Air Cleaning System (ACS) designed to reduce bioaerosol levels. Methods Bioaerosol sampling was undertaken in the absence of clinical activity (baseline) and also during treatment procedures (cavity preparation using an air rotor, history and oral examination, ultrasonic scaling and tooth extraction under local anaesthesia). For each treatment, bioaerosols were measured for two patient episodes (with and without ACS operation) and between five and nine bioaerosol samples were collected. For baseline measurements, 15 bioaerosol samples were obtained. For bioaerosol sampling, environmental air was drawn on to blood agar plates using a bioaerosol sampling pump placed in a standard position 20 cm from the dental chair. Plates were incubated aerobically at 37 degrees C for 48 hours and resulting growth quantified as colony forming units (cfu/m(3)). Distinct colony types were identified using standard methods. Results were analysed statistically using SPSS 12 and Wilcoxon signed rank tests. Results The ACS resulted in a significant reduction (p = 0.001) in the mean bioaerosols (cfu/m(3)) of all three clinics compared with baseline measurements. The mean level of bioaerosols recorded during the procedures, with or without the ACS activated respectively, was 23.9 cfu/m(3) and 105.1 cfu/m(3) (p = 0.02) for cavity preparation, 23.9 cfu/m(3) and 62.2 cfu/m(3) (p = 0.04) for history and oral examination; 41.9 cfu/m(3) and 70.9 cfu/m(3) (p = 0.01) for ultrasonic scaling and 9.1 cfu/m(3) and 66.1 cfu/m(3) (p = 0.01) for extraction. The predominant microorganisms isolated were Staphylococcus species and Micrococcus species. Conclusion These findings indicate potentially hazardous bioaerosols created during dental procedures can be significantly reduced using an air cleaning system.

The microbial signature of aerosols produced during the thermophilic phase of composting.

Abstract: Aims: The microbial diversity of bioaerosols released during operational activities at composting plants is poorly understood. Identification of bacteria and fungi present in such aerosols is the prerequisite for the definition of microbial indicators that could be used in dispersal and exposure studies. Methods and Results: A culture-independent analysis of composting bioaerosols collected at five different industrial open sites during the turning of composting piles in fermentation was performed by building 16S rDNA and 18S rDNA libraries. More than 800 sequences were analysed. Although differences in the phylotypes distribution were observed from one composting site to another, similarities in the structure of microbial diversity were remarkable. The same phyla dominated in the five bioaerosols: Ascomycota among fungi, Firmicutes and Actinobacteria among bacteria. For each phylum, some dominant phylotypes were common to at least four bioaerosols. These common phylotypes belonged to Thermomyces, Aspergillus, Penicillium, Geobacillus, Planifilum, Thermoactinomyces, Saccharopolyspora, Thermobifida and Saccharomonospora. Conclusions: The microbial signature of aerosols produced during the thermophilic phase of composting was determined. The similarities observed may be explained by the selection of thermophilic and sporulating species. Significance and Impact of the Study: Several bacteria and fungi identified in this study may represent potential indicators of composting bioaerosols in air.

Performance of an Electrostatic Precipitator with Superhydrophobic Surface when Collecting Airborne Bacteria

Abstract: Modern bioaerosol sampling and analysis techniques that enable rapid detection of low bioagent concentrations in various environments are needed to help us understand the causal relationship between adverse health effects and bioaerosol exposures and also to enable the timely biohazard detection in case of intentional release. We have developed a novel bioaerosol sampler, an electrostatic precipitator with superhydrophobic surface (EPSS), where a combination of electrostatic collection mechanism with superhydrophobic collection surface allows for efficient particle collection, removal, and concentration in water droplets as small as 5 μ L. The sampler's performance at different sampling flow rates and sampling times was tested with two common bacteria: Pseudomonas fluorescens and Bacillus subtilis. The collection efficiency was determined using the traditional method of microscopic counting as well as the whole-cell quantitative real-time polymerase chain reaction assay (QPCR). The tests indicated that th...

Exposure to Bioaerosol from Sewage Systems

Abstract: Bioaerosols are conglomerates of biological particles such as bacterial and fungal propagules and are produced in sewers and sewage treatment plants through evaporation and turbulence. In order to evaluate the hazard to employees in wastewater treatment plants, airborne microorganisms were measured at two different sites in the sewage systems and in the grit chamber of a treatment plant. Two additional samples were taken during high-pressure cleaning in the relief sewer. Outdoor air samples served as background values. Airborne microorganisms were collected using the impaction method with the MAS-100® and the impingement method with the SKC Biosampler®. The concentrations of coliform bacteria as well as the fungal species Aspergillus fumigatus were determined in addition to mesophilic bacteria counts (cfu/m³). The highest concentrations of mesophilic bacteria were found in the encased grit chamber. Coliform bacteria were found infrequently only in the aerosol of the sewage systems; A. fumigatus was detected at all sampling sites both indoors as well as outdoors. During high-pressure cleaning, total bacteria concentrations reached up to 4.0 × 104 cfu/m3, coliforms up to 3.0 × 103 cfu/m3. These results show that personnel protective measures should be recommended to decrease the exposure risk to biological particles.

Temporal and spatial patterns of ambient endotoxin concentrations in Fresno, California.

Abstract: BackgroundEndotoxins are found in indoor dust generated by human activity and pets, in soil, and adsorbed onto the surfaces of ambient combustion particles. Endotoxin concentrations have been assoc...

Metalworking fluid-related aerosols in machining plants.

Abstract: Respiratory problems are observed in machinists using soluble metalworking fluid (MWF). Evidences suggest that these problems could be related to the aerosolized microorganisms and their byproducts from MWF. To establish MWF aerosol exposure thresholds and to better understand their effect on human health, these aerosols must be fully characterized. This article evaluates airborne microorganisms and aerosols from soluble MWF in the working environment. Air quality parameters (endotoxin levels, culturable airborne microorganisms, fluid mist, inhalable dust and air exchange rates) were evaluated at 44 sites, in 25 shops in Quebec, Canada. Microorganism concentrations were also measured in MWF. Culturable airborne bacteria concentrations were low, ranging from 1.2 × 101 to 1.5 × 103 CFU (colony forming units) m− 3, even for metalworking fluid highly contaminated by bacteria (up to 2.4 × 109 CFU mL− 1). Inhalable dust varied between < 0.1 to 2.6 mg m− 3, while air exchange rates were mostly below the standard...

Aerosols; Science and Technology

Abstract: Introduction INTRODUCTION TO AEROSOLS Introduction Aerosol Phenomenology Drag Force and Diffusivity Diffusion Charging of Aerosol Particles Fractal Aggregates Coagulation Laser-Induced Aerosols Conclusion PART I: Aerosol Formation HIGH-TEMPERATURE AEROSOL SYSTEMS Introduction Main High-Temperature Processes for Aerosol Formation Basic Dynamic Processes in High-Temperature Aerosol Systems Particle Tailoring in High-Temperature Processes AEROSOL SYNTHESIS OF SINGLE-WALLED CARBON NANOTUBES Introduction Aerosol-Unsupported Chemical Vapor Deposition Methods Control and Optimization of Aerosol Synthesis Carbon Nanotube Bundling and Growth Mechanisms Integration of the Carbon Nanotubes Summary CONDENSATIONS, EVAPORATION, NUCLEATION Introduction Condensation Condensation in the Transition Regime Evaporation Uptake Balancing Fluxes Nucleation Nucleation-Controlled Processes Conclusion COMBUSTION-DERIVED CARBONACEOUS AEROSOLS (SOOT) IN THE ATMOSPHERE: WATER INATERACTION AND CLIMATE EFFECTS Black Carbon Aerosols in the Atmosphere: Emissions and Climate Effects Physico-Chemical Properties of Black Carbon Aerosols Water Uptake by Black Carbons Conclusions RADIOACTIVE AEROSOLS - CHERNOBYL NUCLEAR POWER PLANT CASE STUDY Introduction Environmental Aerosols Aerosols inside the Vicinity of the "Shelter" Building PART II: Aerosol Measurement and Characterization APPLICATIONS OF OPTICAL METHODS FOR MICROMETER AND SUBMICROMETER PARTICLE MEASUREMENTS Introduction Optical Methods in Particle Measurements Short Overview of Light Scattering Theories Classification of Optical Instruments for Particle Measurements Development of Airborne and Liquid-borne Particle Counters and Sizers New Methods Used to Characterize the Electrical Charge and Density of the Particles Aerosol Analyzers for Measurement of the Complex Refractive Index of Aerosol Particles Comparison of Commercially Available Instruments and Analysis of the Trends of Further Developments Conclusions THE INVERSE PROBLEM AND AEROSOL MEASUREMENTS Introduction Forms of Representation of Particle Size Distribution Differential and Integral Measurements Differential Mobility Analysis Diffusion Aerosol Spectrometry Conclusions PART III: Aerosol Removal HISTORY OF DEVELOPMENT AND PRESENT STATE OF POLYMERIC FINE-FIBER UNWOVEN PETRYANOV FILTER MATERIALS FOR AEROSOL ENTRAPMENT DEPOSITION OF AEROSOL NANOPARTICLES IN MODEL FIBROUS FILTERS Introduction Results of Numerical Modeling of Nanoparticle Deposition in Two-Dimensional Model Filters Penetration of Nanoparticles through Wire Screen Diffusion Batteries Conclusion FILTRATION OF LIQUID AND SOLID AEROSOLS ON LIQUID-COATED FILTERS Introduction Wettable Filtration Materials Non-Wettable Filtration Materials Filtration on a Porous Medium Submerged into a Liquid PART IV: Atmospheric and Biological Aerosols ATMOSPHERIC AEROSOLS General Concepts Atmospheric Aerosols of Different Nature Temporal and Dimensional Structure of Atmospheric Aerosols Aerosols in the Stratosphere BIOLOGICAL AEROSOLS Introduction History of Bioaerosol Research Main Definitions and Types of Bioaerosol Particles Sources of Biological Particles and their Aerosolization Sampling and Collection Analysis Real-Time Measurement of Bioaerosols Purification of Indoor Air Contaminated with Bioaerosol Particles and Respiratory Protection ATMOSPHERIC BIOAEROSOLS Introduction Methods of Atmospheric Bioaerosol Research Atmospheric Bioaerosol Studies Conclusion

Use of a Foam Spatula for Sampling Surfaces after Bioaerosol Deposition

Abstract: The present study had three goals: (i) to evaluate the relative quantities of aerosolized Bacillus atrophaeus spores deposited on the vertical, horizontal top, and horizontal bottom surfaces in a chamber; (ii) to assess the relative recoveries of the aerosolized spores from glass and stainless steel surfaces with a polyester swab and a macrofoam sponge wipe; and (iii) to estimate the relative recovery efficiencies of aerosolized B. atrophaeus spores and Pantoea agglomerans using a foam spatula at several different bacterial loads by aerosol distribution on glass surfaces. The majority of spores were collected from the bottom horizontal surface regardless of which swab type and extraction protocol were used. Swabbing with a macrofoam sponge wipe was more efficient in recovering spores from surfaces contaminated with high bioaerosol concentrations than swabbing with a polyester swab. B. atrophaeus spores and P. agglomerans culturable cells were detected on glass surfaces using foam spatulas when the theoretical surface bacterial loads were 2.88 × 104 CFU and 8.09 × 106 CFU per 100-cm2 area, respectively. The median recovery efficiency from the surfaces using foam spatulas was equal to 9.9% for B. atrophaeus spores when the recovery was calculated relative to the theoretical surface spore load. Using a foam spatula permits reliable sampling of spores on the bioaerosol-exposed surfaces in a wide measuring range. The culturable P. agglomerans cells were recovered with a median efficiency of 0.001%, but staining the swab extracts with fluorescent dyes allowed us to observe that the viable cell numbers were higher by 1.83 log units than culturable organisms. However, additional work is needed to improve the analysis of the foam extracts in order to decrease the limit of detection of Bacillus spores and Gram-negative bacteria on contaminated surfaces.

Method for Studying Survival of Airborne Viable Microorganisms in Combustion Environments: Development and Evaluation

Abstract: Inactivation of airborne microorganisms due to thermal or chemical air treatment has gained considerable attention. Destruction of aerosolized biothreat agents in environments containing combustion products is particularly relevant to military and counterterrorism situations because some pathogens may survive an explosion or fire in a bio-weapon facility and be dispersed in the atmosphere. Energetic materials with biocidal properties are being sought to effectively inactivate stress-resistant aerosolized microorganisms. Consequently, appropriate methods are needed to test these materials. We designed and built a state-of-the-art experimental facility and developed protocols for assessing the survival of aerosolized microorganisms exposed to combustion. The facility uses a continuous-flow design and includes an aerosolization unit, a test (combustion) chamber, and a measurement system for bioaerosol particles exposed to combustion environments for sub-second time intervals. The experimental method was tested with Bacillus endospores. We assessed the inactivation of aerosolized spores exposed to a gaseous hydrocarbon flame and to combustion of aluminum-based energetic composites (including a novel iodine-containing filled nanocomposite material). Two combustion configurations were evaluated – a vertical strand containing a consolidated material and a specially designed burner in which a fuel powder is fed into a gaseous hydrocarbon flame. It was established that the bioaerosol inactivation may be overestimated due to exposure of spores on collection filters to the combustion products throughout the test. The overestimation can be mitigated by reducing the collection time and minimizing the formation of soot. The experimental facility and method developed in this study enables evaluating effects caused by biocidal products during combustion. The present version of the set-up provides the capability of detecting inactivation levels of ~2.2 × 10 5 (over five-log viability reduction) its further design modifications can potentially enable measuring bioaerosol inactivation as high as ~10 7 . The method was utilized for establishing feasibility of the new iodine-containing material for microbial agent defeat applications. Keyword: Bioaerosols; Combustion aerosols; Hazardous air pollutants.

Microbiological Air Contamination in Poultry Houses

Abstract: Since intensive poultry production is accompanied by as high as possible densities of birds within buildings, this exposes poultry house workers to elevated concentrations of bioaerosol that is mainly emitted by birds. Exposure to dust containing pathogenic microbial and parasitic agents may cause asthma, asthma-like syndrome, mucous membrane irritation, chronic bronchitis, and allergic alveolitis organic dust toxic syndrome, as well as chronic obstructive pulmonary diseases. Since the microbial air pollution data base of poultry houses is insufficient at present, and poultry production is increasingly widespread, it is important to collect, compare and update the available data.

Inactivation of Fungal Spores Collected on Fibrous Filters by Melaleuca alternifolia (Tea Tree Oil)

Abstract: Microbial aerosols could cause various human and animal health problems and their control is becoming a significant scientific and technological topic for consideration. Filtration is considered to be one of the main processes of the removal of biological aerosols from the air carrier minimizing bioaerosol concentration in industrial and domestic dwellings. However, with regards to biologically active particles, their removal from the air carrier does not solely solve the problem of microbial contamination of the ambient air. Considering that in some situations bioaerosol particles collected on the filter could re-enter the air carrier, some disinfection is required to ensure that no biologically active particles could possibly be removed from the filter surface and reach human occupied areas. This article describes the results of laboratory investigations involving Melaleuca alternifolia (tea tree oil) as disinfecting media for inactivation of common environmental fungal spores on the filter surface. It ...

Assessment of bioaerosols at a concentrated dairy operation

Abstract: Increased bioaerosol loadings in down- wind plumes from concentrated animal feeding oper- ations (CAFOs) may increase the risk for allergy and infection in humans. In this study, we monitored airborne concentrations of culturable bacteria and fungi at upwind (background) and downwind sites at a 10,000 milking cow dairy over the course of a year. The average bacterial concentrations at the upwind site were 8.4 9 10 3 colony forming units (CFU) m -3 and increased to 9.9 9 10 5 CFU m -3 at the down- wind edge of the cattle lots, decreasing to 6.3 9 10 4 CFU m -3 200 m farther downwind. At the same sites, the average fungal concentrations were 515, 945, and 1,010 CFU m -3 , respectively. Significant correla- tions between the ambient weather conditions and airborne fungal and bacterial concentrations were identified. Sequence analysis of PCR-amplified DNA from bacterial clones and fungal isolates revealed genus and species level differences between upwind and downwind sites. Although we could not cultivate gram-negative bacteria, bacterial clones at downwind sites identified as being gram-negative matched with the following genera: Acinetobacter, Bradyrhiz- obium, Escherichia, Idiomarina, Methylobacterium, Ralstonia, and Novosphingobium. Fungal isolates from downwind matched with the following genera: Acremonium, Alternaria, Ascomycte, Aspergillus, Basidiomycete, Cladosporium, Davidiella, Doratomy- ces, Emericella, Lewia, Onygenales, Penicillium, Rhizopus, and Ulocladium. None of the bacterial and fungal sequence matches were affiliated with genera and species known to be pathogenic to humans. Overall, the data suggest that exposure to bioaerosols in the downwind environment decreases with increas- ing distance from the open-lot dairy.

Airborne microorganisms associated with waste management and recovery: biomonitoring methodologies.

Abstract: This paper presents preliminary results from a year-long indoor bioaerosol monitoring performed in three working environments of a municipal composting facility treating green and organic waste. Composting, whereby organic matter is stabilized through aerobic decomposition, requires aeration, causing the dispersion of microbial particles (microorganisms and associated toxins). Waste can, therefore, become a potential source of biological hazard. Bioaerosol samples were collected on a monthly basis. Through a comparison of results obtained using two samplers - the Surface Air System DUO SAS 360 and the BioSampler - the study aimed at assessing the presence of biological pollutants, and at contributing to the definition of standard sampling methods for bioaerosols leading, eventually, to the establishment of exposure limits for these occupational pollutants.

Exposure to bioaerosols during the growth season of tomatoes in an organic greenhouse using Supresivit (Trichoderma harzianum) and Mycostop (Streptomyces griseoviridis).

Abstract: In working environments, especially in confined spaces like greenhouses, elevated concentrations of airborne microorganisms may become a problem for workers' health. Additionally, the use of microbial pest control agents (MPCAs) may increase exposure to microorganisms. The aim of this study was to investigate tomato growers' exposure to naturally occurring bioaerosol components [dust, bacteria, fungi, actinomycetes, (1-->3)-beta-D-glucans, and endotoxin] and MPCAs applied by drip irrigation. Airborne dust was collected with filter samplers and analyzed for microorganisms by plate counts and total counts using a microscope. Analysis of (1-->3)-beta-D-glucan and endotoxin content was performed by kinetic, chromatic Limulus amoebocyte lysate tests. The fungal strain (Trichoderma harzianum) from the biocontrol product Supresivit was identified by PCR analysis. Measurements were performed on the day of drip irrigation and 1 week, 1 month, and 3 months after the irrigation. T. harzianum from Supresivit could be detected only on the day of treatment. Streptomyces griseoviridis, an applied MPCA, was not detected in the air during this investigation. We found that bioaerosol exposure increases during the growth season and that exposure to fungi, bacteria, and endotoxin can reach levels during the harvest period that may cause respiratory symptoms in growers. The collected data indicate that MPCAs applied by drip irrigation do not become airborne later in the season.

Design and application of an inertial impactor in combination with an ATP bioluminescence detector for in situ rapid estimation of the efficacies of air controlling devices on removal of bioaerosols.

Abstract: We proposed a rapid method to estimate the efficacies of air controlling devices in situ using ATP bioluminescence in combination with an inertial impactor. The inertial impactor was designed to have 1 mum of cutoff diameter, and its performance was estimated analytically, numerically, and experimentally. The proposed method was characterized using Staphylococcus epidermidis, which was aerosolized with a nebulizer. The bioaerosol concentrations were estimated within 25 min using the proposed method without a culturing process, which requires several days for colony formation. A linear relationship was obtained between the results of the proposed ATP method (RLU/m(3)) and the conventional culture-based method (CFU/m(3)), with R(2) 0.9283. The proposed method was applied to estimate the concentration of indoor bioaerosols, which were identified as a mixture of various microbial species including bacteria, fungi, and actinomycetes, in an occupational indoor environment, controlled by mechanical ventilation and an air cleaner. Consequently, the proposed method showed a linearity with the culture-based method for indoor bioaerosols with R(2) 0.8189, even though various kinds of microorganisms existed in the indoor air. The proposed method may be effective in monitoring the changes of relative concentration of indoor bioaerosols and estimating the effectiveness of air control devices in indoor environments.