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AbstractThe human living environment serves as a habitat for microorganisms and the presence of ubiquitous airborne microbes significantly impacts the natural material cycle. Through ongoing experimentation with beneficial microorganisms, humans have greatly benefited from airborne microbes. However, airborne pathogens endanger human health and have the potential to induce fatal diseases. Tracking airborne microbes is a critical prerequisite for a better understanding of bioaerosols, harnessing their potential advantages, and mitigating associated risks. Although technological breakthroughs have enabled significant advancements in accurately monitoring airborne pathogens, many puzzles about these microbes remain unanswered due to their high variability and environmental diffusibility. Consequently, advanced techniques and strategies for special identification, early warning, and efficient eradication of microbial contamination are continuously being sought. This review presents a comprehensive overview of the research status of airborne microbes, concentrating on the recent advances and challenges in sampling, detection, and inactivation. Particularly, the fundamental design principles for the collection and timely detection of airborne pathogens are described in detail, as well as critical factors for eliminating microbial contamination and enhancing indoor air quality. In addition, future research directions and perspectives for controlling airborne microbes are also suggested to promote the translation of basic research into real products. [ABSTRACT FROM AUTHOR]

In a mass casualty medical evacuation after a bioaerosol (BA) dispersal event, a decontamination (DC) method is needed that can both decontaminate and prevent biological particle (BP) re-aerosolization (RA) of contaminated clothes. However, neither the efficacy of current DC methods nor the risk of BP RA is greatly explored in the existing literature. The goals of this study were to develop a repeatable method to quantify the RA of a biological contaminant off military uniform fabric swatches and to test the efficacy of one DC protocol (high-volume, low-pressure water) using 1 µm polystyrene latex (PSL) spheres as a surrogate. A four-step methodology was developed: contamination using a Collison Nebulizer; RA using a laboratory mixer and aerosol collection using an inhalable air sampler with a polyvinyl chloride filter; DC using a gravity-fed water shower; and quantification using ultraviolet microscopy via both visual and computer techniques. All results for uncontaminated control samples showed little to no presence of PSL sphere-like particles, while the contaminated experimental trials showed that RA was much lower after DC with water at the 99% confidence level (p-value = 0.0081). The water DC showed an average ∼73% reduction in particle RA, along with a change in air sampler filter deposition patterns from aerosol-like (before DC) to droplet-like (after DC). The fluorescent sphere contamination method for testing the DC residual risk of RA was repeatable and successful. [ABSTRACT FROM AUTHOR]

This study aimed to measure the levels of airborne radon Rn and bioaerosols – culturable airborne bacteria (CAB) and culturable airborne fungi (CAF)—in South Korea's residential environments, considering living conditions such as the number of ventilations, number of windows, floors, temperature, and relative humidity.. The range of Rn levels was 0.43–7.439 pCi/L with a median of 0.70 pCi/L. The CAB levels were 239–488 colony-forming unit (CFU)/m3 with a median of 309 CFU/m3, and CAF levels were 174–366 CFU/m3 with a median of 233 CFU/m3. Thus, this study found that semi-basement residential indoor environments negatively affected Rn and bioaerosol levels, and living in such residences resulted in high health condition scores on the bad side. Given the correlation between airborne Rn and bioaerosol levels, further large-scale studies are needed to identify more reliable and representative of research. [ABSTRACT FROM AUTHOR]

This review emphasizes the importance of classification of surface reservoirs represented by building and indoor materials. Models developed in the past 45 years to study mainly non-reactive thermodynamic partitioning of air pollutants to surfaces as well as their validation through analytical measurements are discussed. Analytical techniques aiming at surface characterization have been summarized. Applications relevant to surface chemistry performed indoors in the last decade are also given. Finally, techniques for microbiological sampling to characterize the hygienic state of surfaces have also been compiled. Readers will be introduced to the state-of-the-art of analytical techniques that are being used indoors for (physico)chemical and microbiological characterization of surfaces. The focus is on real-time in situ instrumentation used to understand chemical processes rather than air quality monitoring indoors. Our aim was to give an overview of useful instrumentation and a tutorial on analytical approaches and challenges represented by surfaces. [ABSTRACT FROM AUTHOR]

For many agents, the aerodynamic particle size can affect both the virulence and disease course in animal models. Botulinum neurotoxins (BoNTs), which are widely known as potential bioterrorism agents, have been shown to be toxic via multiple routes of exposure, including small particle inhalation (1–3 µm MMAD). However, the impact of larger particle sizes on the potency of BoNT has not been previously reported. In this study, we compared the potency of BoNT in small and large particle aerosols. Outbred mice (ICR (CD-1®)) were exposed to BoNT-containing aerosols with differing mass median aerodynamic diameters (MMADs) of 1.1, 4.9, and 7.6 microns. The effects of bioaerosol sampler and inhalation exposure modality were studied. Collecting aerosolized BoNT onto gelatin filters or into liquid impingers resulted in equivalent estimates of aerosol concentration. Nose-only and whole-body inhalation exposure resulted in nearly identical estimates of the median lethal dose (LD50). The LD50 for inhaled BoNT increased approximately 50-fold when the median aerodynamic particle size was increased from 1.1 to 4.9 µm, from 139 (95% CI: 111–185) to 7324 (95% CI: 4287–10 891) mouse intraperitoneal median lethal doses (MIPLD50). These results demonstrate the importance of aerodynamic particle size and regional deposition patterns with regards to BoNT inhalational toxicity. These data will be useful for medical countermeasure development, as well as biodefense preparedness modeling by demonstrating that the estimates of dose and toxicity of an inhaled aerosol containing BoNT can be significantly affected by a range of factors. [ABSTRACT FROM AUTHOR]

Bioaerosol sampling is a critical step toward characterizing airborne pathogen exposure risks for many respiratory infectious diseases in human-to-human or human-to-animal outbreaks. The integrated performance-parameter design and sampling efficiency of aerosol-to-hydrosol samplers (cyclones) has been rarely published or studied. This review focuses on the determination of cyclone performance-parameter design and impact factors of the sampling efficiency, discusses their mechanisms of collection and describes their advantages and drawbacks. The crucial design parameters of cyclones in different applications are then discussed in detail. We also discuss how the aerosol-to-hydrosol sampling efficiency is intrinsically related to the performance parameters for bioaerosol cyclone design. In the final section of this review, scientific questions and challenges for future work are presented to encourage high collection efficiency design and high-quality cyclones. [ABSTRACT FROM AUTHOR]

Water-miscible metalworking fluids (MWFs) are used in metal removal and forming operations. For end use, formulation concentrates are diluted in water, providing conditions conducive to microbial growth and metabolism and potentially causing fluid biodeterioration and microbiologically influenced corrosion. Microorganisms in the environment are highly diverse, and bacteria and fungi have been recovered from these fluids at population densities of >106 CFU mL−1. Thus, to control microbial bioburdens in MWFs, microbicides are often incorporated into MWF formulations, used as tankside additives, or both. Some microbicides are suspected as being responsible for adverse health effects. Consequently, their usage has been restricted in recently adopted regulations. Given the limited number of microbicides currently approved for use in MWFs, alternative microbial contamination control strategies are needed. Some of these strategies have already been employed in the market. Studies on microorganisms in MWFs are often hindered by the complexity of the media, especially when trying to examine in-use samples. Historically, microbiological analyses were primarily based on cultivation assays using nutrient-rich media. These analyses have severe disadvantages, and the adoption of more reliable test methods is of utmost importance. Here, we review MWF microbiology, discussing possible consequences and options for both control and condition monitoring testing. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Pullorum (S. Pullorum) is an important pathogen specific to avian species, which poses a serious threat to the poultry industry. The transmission of S. Pullorum occurs both horizontally and vertically but the airborne transmission of S. Pullorum has been neglected historically. In this study, the effects of aerosolized S. Pullorum on young chickens were investigated. The results showed that the colonization and morbidity induced by bioaerosol infection are dose dependent. The bacteria colonized in chicken lung for more than 14 days following the exposure to ≥ 1.25 × 106 CFU/m3 of aerosolized S. Pullorum. Tachypnoea and depression were present in all the chickens between 5 and 7 days after infection, and some died, following the exposure to ≥1.25 × 108 CFU/m3 of aerosolized S. Pullorum. RT–PCR results showed that significant expressions of inflammatory cytokines, including tumour necrosis factor α, interleukin 1β (IL-1β), IL-6, and IL-8 were noted in the lung and spleen. Histopathological examination showed lung swelling, with obvious lesions, including inflammatory cell infiltration, tissue injury, and acute haemorrhage. These results suggest that uncontrolled and detrimental inflammation is caused by a high dose of aerosolized S. Pullorum. These results further extend our understanding of the pathogenicity of air-transmitted S. Pullorum on chickens. RESEARCH HIGHLIGHTS Aerosolized S. Pullorum caused tachypnoea, depression, and lung swelling in chickens. The colonization and morbidity caused by aerosolized S. Pullorum are dose dependent. Detrimental inflammation is caused by high doses of aerosolized S. Pullorum in lung. [ABSTRACT FROM AUTHOR]

The World Health Organization attributed more than four million premature deaths to ambient air pollution in 2016. Numerous epidemiologic studies demonstrate that acute respiratory tract infections and exacerbations of pre-existing chronic airway diseases can result from exposure to ambient (outdoor) air pollution. In this context, the atmosphere contains both chemical and microbial pollutants (bioaerosols), whose impact on human health remains unclear. Therefore, this review: summarises the findings from recent studies on the association between exposure to air pollutants—especially particulate matter and ozone—and onset or exacerbation of respiratory infections (e.g. pneumonia, cystic fibrosis lung infection, and tuberculosis); discusses the mechanisms underlying the relationship between air pollution and respiratory bacterial infections, which is necessary to define prevention and treatment strategies; demonstrates the relevance of air pollution modelling in investigating and preventing the impact of exposure to air pollutants on human health; and outlines future actions required to improve air quality and reduce morbidity and mortality related to air pollution. [ABSTRACT FROM AUTHOR]

We aimed to assess the occurrence of bovine viruses (bovine leukemia virus–BLV and bovine adenovirus–BAdV) at workplaces in traditional dairies and to evaluate the potential role of airborne and surface contamination in spreading of these viruses derived from raw milk. The total amount of 122 samples—including 37 air (bioaerosol), 40 surface, and 45 milk samples—were checked for the presence of BLV and BAdV genomes using RT-qPCR/qPCR method. The study showed that the viruses were present in 7 air (among them 71.4% were BLV-positive and 28.6% were BAdV-positive), 14 surface (among them 85.7% were BLV-positive and 14.3% were BAdV-positive), and 34 milk (all were BLV-positive only) samples. Statistical analysis revealed that both the air and surfaces in studied occupational environment were more frequently contaminated with BLV than with BAdV (Chi-square test: p = 0.002, Fisher's Exact test: p = 0.002). Kruskal-Wallis tests showed significant differences in BLV genome concentrations in the air (p = 0.045) as well as in BLV and BAdV genome concentrations on surfaces (p = 0.005 and p = 0.040, respectively) between studied processing areas. In units of genome copies (gc) per area, the highest concentrations of BLV and BAdV genomes in the air (9.8 × 101 ± 1.14 × 102 gc/m3 and 5.4 × 101 ± 9.1 × 101 gc/m3, respectively) and on surfaces (9.83 × 102 ± 7.41 × 102 gc/100cm2 and 2.30 × 102 ± 3.8 × 102 gc/100cm2, respectively) were observed in milk reception area. The air and surfaces of pre-production zones were also significantly more contaminated with BAdV genomes compared to production areas (Mann-Whitney test: p = 0.039 and p = 0.029, respectively). This study showed that dairy workers may be exposed to bovine viruses through the inhalation of bioaerosols and contact with contaminated surfaces. To reduce the probability of virus transmission from the raw milk to humans, efficient surface cleaning procedures degrading viral particles should be introduced and the use of personal protection equipment, especially within pre-production zones, should be required. As the raw milk may be a source of bovine viruses, the development of strategies for both the control and eradication of BLV and BAdV among cattle seems to be also urgently needed. [ABSTRACT FROM AUTHOR]

The primary purpose of this study was to critically review published data related to the sources and mechanisms of aerosolization of microorganisms, their fragments and metabolites in a variety of occupational environments. The processes and mechanisms considered in the review include bursting bubbles; liquid dispersion as the result of irrigation, separation, high pressure cleaning and technological water recycling; manual and automated handling of contaminated material in agriculture, waste processing and industrial processes; as well as high temperature industrial processes. The review identifies the gaps in the existing knowledge regarding the sources of bioaerosol, aerosolization mechanisms, bioaerosol distribution and potential risks for the workers and residents. The study also reviews the existing laboratory methods of bioaerosol generation with particular focus on the advantages and shortcomings of each method. [ABSTRACT FROM AUTHOR]

This study investigated a potential correlation between deposited macroparticles >5μm and bioaerosols. Bioaerosols were detected using both passive (culture plates) and dynamic sampling (biocollectors). Bioaerosols were then revealed visually on culture plates after incubation and counted in colony forming unit (CFU)/cm2. Macroparticles were counted on line by CLEAPART-100 (patent CEA - Aix Marseille University - Winlight System). It enables continuous monitoring of the deposit of macroparticles on surfaces. We have shown that those macroparticles could be strongly correlated to viable particle measurements (bacteria and mould) after dynamic sampling by biocollectors. As viable particle measurements require an incubation period of at least 48 hours, it is easy to understand the advantage in continuous macroparticle done by CLEAPART-100. CLEAPART-100 is therefore an instrument which enables the alert to be raised in relation to any contamination or biocontamination events. [ABSTRACT FROM AUTHOR]

Increased understanding of influenza transmission is critical for pandemic planning and selecting appropriate controls for healthcare personnel safety and health. The goals of this pilot study were to assess environmental contamination in different areas and at two time periods in the influenza season and to determine the feasibility of using surgical mask contamination to evaluate potential exposure to influenza virus. Bioaerosol samples were collected over 12 days (two 6-day sessions) at 12 locations within a student health center using portable two-stage bioaerosol samplers operating 8 hr each day. Surface samples were collected each morning and afternoon from common high-contact non-porous hard surfaces from rooms and locations where bioaerosol samplers were located. Surgical masks worn by participants while in contact with patients with influenza-like illness were collected. A questionnaire administered to each of the 12 participants at the end of each workday and another at the end of each workweek assessed influenza-like illness symptoms, estimated the number of influenza-like illness patient contacts, hand hygiene, and surgical mask usage. All samples were analyzed using qPCR. Over the 12 days of the study, three of the 127 (2.4%) bioaerosol samples, 2 of 483 (0.41%) surface samples, and 0 of 54 surgical masks were positive for influenza virus. For the duration of contact that occurred with an influenza patient on any of the 12 days, nurse practitioners and physicians reported contacts with influenza-like illness patients >60 min, medical assistants reported 15-44 min, and administrative staff reported <30 min. Given the limited number of bioaerosol and surface samples positive for influenza virus in the bioaerosol and surface samples, the absence of influenza virus on the surgical masks provides inconclusive evidence for the potential to use surgical masks to assess exposure to influenza viruses. Further studies are needed to determine feasibility of this approach in assessing healthcare personnel exposures. Information learned in this study can inform future field studies on influenza transmission. [ABSTRACT FROM AUTHOR]

Payatas landfill site is one of the major dumpsites in the Philippines. In this study, the landfill was evaluated regarding the presence and concentration of pathogenic bacterial aerosols through culture and molecular techniques. Bioaerosols are biological airborne particles that may or may not cause diseases. Active sampling was done using MAS-100 Air Sampler from both indoor and outdoor locations. To test the accuracy of the culture method, those that were presumptively identified asStaphylococcus aureusandKlebsiella pneumoniaewere subjected to molecular analysis using 16s rRNA sequencing, and as a result, they were identified as different species. The exposure assessment done by interview showed matches among prevalent diseases. The results of this study can be used as a basis for creating standards and regulations for workers' and residents' safety and health in the landfill site. [ABSTRACT FROM AUTHOR]

Dairy workers experience a high degree of bioaerosol exposure, composed of an array of biological and chemical constituents, which have been tied to adverse health effects. A better understanding of the variation in the magnitude and composition of exposures by task is needed to inform worker protection strategies. To characterize the levels and types of exposures, 115 dairyworkers grouped into three task categories on nine farms in the high plainsWesternUnited States underwent personal monitoring for inhalable dust, endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, ergosterol, and ammonia through one work shift. Eighty-nine percent of dairy workers were exposed to endotoxin at concentrations exceeding the recommended exposure guidelines (adjusted for a long work shift). The proportion of workers with exposures exceeding recommended guidelines was lower for inhalable dust (12%), and ammonia (1%). Ergosterol exposureswere onlymeasurable on 28%of samples, primarilyamongmedicalworkers and feed handlers. Milking parlor workers were exposed to significantly higher inhalable dust, endotoxin, 3-OHFA, ammonia, and muramic acid concentrations compared to workers performing other tasks. Development of large modern dairies has successfully made progress in reducingworker exposures and lung disease prevalence. However, exposure to endotoxin, dust, and ammonia continues to present a significant risk toworker health on North American dairies, especially for workers in milking parlors. This study was among the first to concurrently evaluate occupational exposure to assayable endotoxin (lipid A), 3-hydroxy fatty acids or 3-OHFA (a chemical measure of cell bound and noncell-bound endotoxins), muramic acid, ergosterol, and ammonia among workers on Western U.S. dairies. There remains a need for cost-effective, culturally acceptable intervention strategies integrated in OHS Risk Management and production systems to further optimize worker health and farm productivity. [ABSTRACT FROM AUTHOR]

Aerosol aerodynamic particle size is known to affect deposition patterns of inhaled aerosol particles, as well as the virulence of inhaled bioaerosol particles. While a significant amount of work has been performed to describe the deposition of aerosol particles in the human respiratory tract, only a limited amount of work has been performed to describe the deposition of aerosol particles in the respiratory tract of nonhuman primates, an animal model commonly utilized in pharmacological and toxicological studies, especially in the biodefense field. In this study, anesthetized rhesus macaques inhaled radiolabeled aerosols with MMADs of 1.7, 3.6, 7.4 and 11.8 µm to characterize regional deposition patterns. The results demonstrate that the regional deposition pattern shifts as particle size increases, with greater deposition in more proximal regions of the respiratory tract and decreased deposition in the pulmonary region. The results of this study extend the findings of previous studies which demonstrated a similar shift in the deposition pattern as a function of particle size by providing greater resolution of deposition patterns. These data on regional deposition patterns provide a starting point to begin to explore potential mechanisms responsible for the differences in virulence of infectious bioaerosols as a function of particle size and deposition pattern reported in previous studies. Additionally, the data are useful to assess the performance of various deposition models that have been published in the literature. [ABSTRACT FROM AUTHOR]

Since this era, almost all children temporize most of their time outside home within the kindergarten environment, so the importance of this environment indoor air quality has been increasingly considerable. The aim of this study was to survey of airborne fungal flora in the indoor air of day Care Child Centers (DCCs) located in Delfan. The air temperature (°C), relative humidity (%), air velocity (m/s), and fungi density and flora were measured in four DCCs. In addition, information on each DCC characteristics was collected via an observation and officer questioning. Fungi sampling was performed using impaction technique (28.3 L/min) for 10 min. The mean temperature of indoors is 24.5 ± 1.5 °C. Relative humidity of the air was 42.7 ± 7.1%, which is depending on sampling place. The most isolated fungal species wasPenicillium Spp.For Bagh-e-Koodak child care center. Maximum and minimum of total fungi (CFU) were 372 CFU or 1314 CFU/m3(Bagh-e-Koodak) VS. 91 CFU or 322 CFU/m3(Dariai-e-Mehr), respectively. There was only a significant difference for RH(%) based on sampling points, while there was significant relation for RH(%), temperature based on DCC,Penicillium spp.,Aspergillus flavusand total fungal count. We conclude that indoor air fungal contamination (density and flora) in studied DCCs are considerable. [ABSTRACT FROM AUTHOR]

Exposure to bioaerosols has been associated with health deterioration among workers in several occupational environments. This highlights the need to study the microbiological quality of air of workplaces as no such study has been conducted yet in the Philippines. To detect and characterize the culturable mesophilic airborne bacteria in selected occupational environments we used passive sedimentation technique. It was observed that the number of colony-forming units was highest in junk shop, followed by the light railway transit station and last the office. By contrast, the bacterial composition was similar in all sites: Gram-positive cocci > Gram-positive bacilli > Gram-negative bacteria.Staphylococcus aureusandBacillusspp. were also detected in all sites. These findings suggest that the presence of airborne bacteria may be a potential health hazard in urban occupational environments in the Philippines. [ABSTRACT FROM AUTHOR]

Aerosolized methicillin-resistant Staphylococcus aureus (MRSA) was sampled inside and downwind of a swine facility. Animal feed was sampled before and after entry into the swine facility. Aerosolized particles were detected using an optical particle counter for real-time measurement and with an Andersen sampler to detect viable MRSA. Molecular typing and antimicrobial susceptibility testing were performed on samples collected. Viable MRSA organisms isolated inside the swine facility were primarily associated with particles >5 µm, and those isolated downwind from the swine facility were associated with particles <5 µm. MRSA isolates included spa types t008, t034, and t5706 and were resistant to methicillin, tetracycline, clindamycin, and erythromycin. Animal feed both before and after entry into the swine facility tested positive for viable MRSA. These isolates were of similar spa types as the airborne MRSA organisms. Air samples collected after power washing with a biocide inside the swine facility resulted in no viable MRSA organisms detected. This pilot study showed that the ecology of MRSA is complex. Additional studies are warranted on the maximum distance that viable MRSA can be emitted outside the facility, and the possibility that animal feed may be a source of contamination. [ABSTRACT FROM AUTHOR]

Online matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is reported within situmatrix/analyte aerosol mixing. The analyte and matrix were dissolved in separate solvents and pneumatically atomized into particles. Continuous flows of analyte particles and matrix droplets in nitrogen were mixed in a tee. The resulting particles were sampled using a nozzle, focused into a beam with an aerodynamic lens system, and vertically deposited continuously on a movable target. The matrix/analyte mixture was desorbed/ionized using a 266 nanometers pulsed laser at an incident angle of 45°. The nascent ions were analyzed using reflectron TOF MS. The performance of online MALDI-TOF MS was evaluated by the analysis of palmityl palmitate with the lithium salt of 2, 4-dihydroxybenzoic acid as the matrix. Strong and stable MALDI signals of palmityl palmitate were obtained. The matrix solvent mixture and the analyte concentration were optimized and the results demonstrate the development of an alternative for online MALDI analysis. [ABSTRACT FROM PUBLISHER]

Prevalent airborne microorganisms are not well characterized in industrial animal production buildings with respect to their quantity or quality. To investigate the work-related microbial exposure, personal bioaerosol sampling during the whole working day is recommended. Therefore, bioaerosol sampling in a duck hatchery and a duck house with two personal air sampling devices, a filter-based PGP and a NIOSH particle size separator, was performed. Subsequent, quantitative and qualitative analyses were carried out with” culture independent methods. Total cell concentrations (TCC) determined via fluorescence microscopy showed no difference between the two devices. In average, 8 × 106cells/m3were determined in the air of the duck hatchery and 5 × 107cells/m3in the air of the duck house. A Generated Restriction Fragment Length Polymorphism (RFLP) pattern revealed deviant bacterial compositions comparing samples collected with both devices. Clone library analyses based on 16S rRNA gene sequence analysis from the hatchery's air showed 65% similarity between the two sampling devices. Detailed 16S rRNA gene sequence analyses showed the occurrence of bacterial species likeAcinetobacter baumannii, Enterococcus faecalis, Escherichia sp., and Shigella sp.; and a group of Staphylococcus delphini, S. intermedius, and S. pseudintermediusthat provided the evidence of potential exposure to risk group 2 bacteria at the hatchery workplace. Size fractionated sampling with the developed by the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) device revealed that pathogenic bacteria would deposit in the inhalable, the thorax, and possibly alveolar dust fraction according to EN481. TCC analysis showed the deposition of bacterial cells in the third stage (< 1μm) at the NIOSH device which implies that bacteria can reach deep into the lungs and contaminate the alveolus after inhalation. Nevertheless, both personal sampling devices could be recommended for exposure assessment at agricultural workplaces. [ABSTRACT FROM AUTHOR]

A chamber was designed and built to study the long-term effects of environmental conditions on air-borne microorganisms. The system consists of a 55.5-L cylindrical chamber, which can rotate at variable speeds on its axis. The chamber is placed within an insulated temperature controlled enclosure which can be either cooled or heated with piezoelectric units. A germicidal light located at the chamber center irradiates at a 360° angle. Access ports are located on the stationary sections on both ends of the chamber. Relative humidity (RH) is controlled by passing the aerosol through meshed tubes surrounded by desiccant. Validation assay indicates that the interior temperature is stable with less than 0.5 °C in variation when set between 18 and 30 °C with the UV light having no effect of temperature during operation. RH levels set at 20%, 50% and 80% varied by 2.2%, 3.3% and 3.3%, respectively, over a 14-h period. The remaining fraction of particles after 18 h of suspension was 8.8% at 1 rotation per minute (rpm) and 2.6% at 0 rpm with the mass median aerodynamic diameter (MMAD) changing from 1.21 ± 0.04 µm to 1.30 ± 0.02 µm at 1 rpm and from 1.21 ± 0.04 µm to 0.91 ± 0.01 µm at 0 rpm within the same time period. This chamber can be used to increase the time of particle suspension in an aerosol cloud and control the temperature, RH and UV exposure; the design facilitates stationary sampling to be performed while the chamber is rotating. [ABSTRACT FROM AUTHOR]

The growing threat of an influenza pandemic presents a unique challenge to healthcare workers, emergency responders, and the civilian population. The Occupational Safety and Health Administration (OSHA) recommends National Institute for Occupational Safety and Health (NIOSH)-approved respirators to provide protection against infectious airborne viruses in various workplace settings. The filtration efficiency of selected NIOSH-approved particulate N95 and P100 filtering facepiece respirators (FFRs) and filter cartridges was investigated against the viable MS2 virus, a non-pathogenic bacteriophage, aerosolized from a liquid suspension. Tests were performed under two cyclic flow conditions (minute volumes of 85 and 135 L/min) and two constant flow rates (85 and 270 L/min). The mean penetrations of viable MS2 through the N95 and P100 FFRs/cartridges were typically less than 2 and 0.03%, respectively, under all flow conditions. All N95 and P100 FFR and cartridge models assessed in this study, therefore, met or exceeded their respective efficiency ratings of 95 and 99.97% against the viable MS2 test aerosol, even under the very high flow conditions. These NIOSH-approved FFRs and particulate respirators equipped with these cartridges can be anticipated to achieve expected levels of protection (consistent with their assigned protection factor) against airborne viral agents, provided that they are properly selected, fitted, worn, and maintained. [ABSTRACT FROM PUBLISHER]

Background: Municipal workers handling household waste are potentially exposed to a variety of toxic and pathogenic substances, in particular airborne bacteria, gram-negative bacteria (GNB), and fungi. However, relatively little is known about the conditions under which exposure is facilitated. Methods: This study assessed levels of airborne bacteria, GNB, and fungi, and examined these in relation to the type of waste-handling activity (collection, transfer, transport, and sorting at the waste pre-processing plant), as well as a variety of other environmental and occupational factors. Airborne microorganisms were sampled using an Andersen single-stage sampler equipped with agar plates containing the appropriate nutritional medium and then cultured to determine airborne levels. Samples were taken during collection, transfer, transport, and sorting of household waste. Multiple regression analysis was used to identify environmental and occupational factors that significantly affect airborne microorganism levels during waste-handling activities. Results: The "type of waste-handling activity" was the only factor that significantly affected airborne levels of bacteria and GNB, accounting for 38% (P=0.029) and 50% (P=0.0002) of the variation observed in bacteria and GNB levels, respectively. In terms of fungi, the type of waste-handling activity (R²=0.76) and whether collection had also occurred on the day prior to sampling (P<0.0001, R²=0.78) explained most of the observed variation. Given that the type of waste-handling activity was significantly correlated with levels of bacteria, GNB, and fungi, we suggest that various engineering, administrative, and regulatory measures should be considered to reduce the occupational exposure to airborne microorganisms in the waste-handling industry. [ABSTRACT FROM AUTHOR]

Portable microbial samplers are useful for detecting microorganisms in the air. However, limited data are available on their performance when sampling airborne biological agents in a routine practice. We compared bacterial and fungal concentrations obtained in field conditions using three impactor samplers with different designs (AES Chemunex Sampl’Air, bioMérieux Air Ideal, and Sartorius AirPort MD8/BACTair). The linearity of mold collection was tested in the range of 100 L to 1000 L, and all the devices had a correlation coefficient higher than 0.95. For optimal comparison of the samplers, we performed experiments in different hospital rooms with varying levels of air biocontamination. Each sampling procedure was repeated to assess reproducibility. No significant difference between the samplers was observed for the mold concentrations on Sabouraud agar, whereas Sampl’Air collected significantly more bacteria on tryptic soy agar than Air Ideal or BACTair at one of the sites. Impactor location in the room was nevertheless associated with the variability observed with the three samplers at the highest microbial concentration levels. On the basis of their performance, autonomy and simplicity of use, these three impactors are suitable for routine indoor evaluation of microbial air contamination. [ABSTRACT FROM PUBLISHER]

The dairy industry is changing on a global scale with larger, more efficient operations. The impact of this change on worker health and safety, specifically, associations between occupational lung disease and inhalation exposures, has yet to be reported in a comprehensive review of the scientific literature. Therefore, a three-tier process was used to identify information using a keyword search of online databases of scientific literature. Of the 147 citations reviewed, 52 met initial screening criteria, and 30 were included in this review. Dairy workers experience lung conditions such as asthma, chronic obstructive pulmonary disease, hypersensitivity pneumonitis, chronic bronchitis, and cancer. Recent pulmonary function studies have identified obstructive lung changes among dairy farm workers. The increased scale of dairy production with significant changes in technology and work practices has altered inhalation exposure patterns among dairy workers. The inhalation exposure in the dairy work environment may elicit differing inflammatory responses in relation to timing of initial exposure as well as to repeated exposures. Few studies have measured inhalation exposure while simultaneously assessing the impact of the exposure on lung function of dairy farm workers. Even fewer studies have been implemented to assess the impact of aerosol control technology to reduce inhalation exposure. Future research should evaluate worker exposure to aerosols through a task-based approach while utilizing novel methods to assess inhalation exposure and associated inflammatory responses. Finally, potential solutions should be developed and tested to reduce inhalation exposure to inflammatory agents and respiratory diseases in the dairy farm work environment. [ABSTRACT FROM AUTHOR]

This study evaluated the filtration performance of four commercially available models of National Institute of Occupational Safety and Health (NIOSH)-certified filtering facepiece respirators (FFR) against both biological and inert aerosols at a flow rate of 85 L/min. Conventional N95 and P100 FFRs and two antimicrobial (AM)-treated FFRs (an N95 and a P95, both with iodine-based AM treatments) were tested for both physical penetration (PENP) and viable penetration (PENV) with three different bioaerosols, including MS2 bacteriophage virus, and the spores and vegetative cells of Bacillus atrophaeus bacteria, in addition to inert sodium chloride (NaCl) aerosol. For each FFR model, the PENP measured with NaCl was predictive of its MS2 PENP, and it was observed that spores and bacteria aerosols were also filtered similarly to the inert aerosol. For both conventional FFRs, up to a 1-log reduction in PENV in comparison with PENP was observed and attributed to the experimental variability of the test system. For both models of AM-FFRs, no statistically significant differences between PENV and PENP for any of the three different bioaerosol challenges were observed. Thus, no bioaerosol filtration enhancement over the conventional FFRs was detected for either iodine-based AM-FFR. In the absence of any standardized test methods, we recommend that future studies evaluating the filtration performance of AM-treated FFRs incorporate the experimental best practices described herein. [Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a pdf file containing I. Review of Research on Antimicrobial-Treated Respirators, and II. Microorganism Propagation, Plating, and Enumeration Protocols.] [ABSTRACT FROM AUTHOR]

In this study, the performance of two newly developed personal bioaerosol samplers for monitoring the level of environmental and occupational airborne microorganisms was evaluated. These new personal bioaerosol samplers were designed based on a swirling cyclone with recirculating liquid film. The performance evaluation included collection efficiency tests using inert aerosols, the bioaerosol survival test using viable airborne microorganism, and the evaluation of using non-aqueous collection liquid for long-period sampling. The test results showed that these two newly developed personal bioaerosol samplers are capable of doing high efficiency, aerosol sampling (the cutoff diameters are around 0.7 μm for both samplers), and have proven to provide acceptable survival for the collected bioaerosols. By using an appropriate non-aqueous collection liquid, these two personal bioaerosol samplers should be able to permit continuous, long-period bioaerosol sampling with considerable viability for the captured bioaerosols. [ABSTRACT FROM PUBLISHER]

This study compared workplace protection factors (WPFs) for five different contaminants (endotoxin, fungal spores, (1→3)-β-D-glucan, total particle mass, and total particle number) provided by an N95 elastomeric respirator (ER) and an N95 filtering facepiece respirator (FFR). We previously reported size-selective WPFs for total particle numbers for the ER and FFR, whereas the current article is focused on WPFs for bioaerosols and total particle mass. Farm workers (n = 25) wore the ER and FFR while performing activities at eight locations representing horse farms, pig barns, and grain handling facilities. For the determination of WPFs, particles were collected on filters simultaneously inside and outside the respirator during the first and last 15 min of a 60-min experiment. One field blank per subject was collected without actual sampling. A reporting limit (RL) was established for each contaminant based on geometric means (GMs) of the field blanks as the lowest possible measurable values. Depending on the contaminant type, 38-48% of data points were below the RL. Therefore, a censored regression model was used to estimate WPFs (WPFcensored). The WPFcensored provided by the two types of respirators were not significantly different. In contrast, significant differences were found in the WPFcensored for different types of contaminants. GMs WPFscensored for the two types of respirators combined were 154, 29, 18, 19, and 176 for endotoxin, fungal spore count, (1→3)-β-D-glucan, total particle mass, and total particle number, respectively. The WPFcensored was more strongly associated with concentrations measured outside the respirator for endotoxin, fungal spores, and total particle mass except for total particle number. However, when only data points with outside concentrations higher than 176×RL were included, the WPFs increased, and the association between the outside concentrations and the WPFs became weaker. Results indicate that difference in WPFs observed between different contaminants may be attributed to differences in the sensitivity of analytical methods to detect low inside concentrations, rather than the nature of particles (biological or non-biological). [ABSTRACT FROM AUTHOR]

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 (4 h- 1) for this type of workplace, between 0.6 to 14.2 h- 1. Only nine of 44 sites respected the suggested minimum value for air exchange rates. Fluid mist ranged from 0.02 to 0.89 mg m- 3, which is below the threshold limit value (TLV) (ACGIH) of 5 mg m- 3. Airborne endotoxin concentrations ranged from undetectable to 183 EU m- 3 (endotoxin units), showing no correlation with airborne microorganisms or inhalable dust. Most workstations respected the suggested minimum values for fluid mist and showed low concentrations of airborne endotoxin, culturable microorganisms and inhalable dust despite fluid contamination, even when air exchange rates were below the recommendations. Airborne Pseudomonas pseudoalcaligenes was recovered from many sites at significant concentrations. Health-associated risks following exposure to this microorganism should be further investigated. [ABSTRACT FROM AUTHOR]

This article describes the development of a novel, high-performance personal aerosol sampler intended to monitor occupational air pollution, specifically, microbial constituents. This prototype sampler has a horizontally positioned conical cyclone with recirculating liquid film and an ejection supply of adsorptive liquid into the inlet nozzle. Airborne pollutants were collected in the adsorptive liquid, thus improving the survivability of microbiological aerosol samples. Experimental modules of different dimensions were first evaluated. Based on the test results, a prototype sampler was fabricated and tested. Evaluation of the collection efficiency of the prototype unit indicated a higher than 90% collection efficiency for particles > 1.0 μ m. The 50% cutoff diameter was between 0.70-0.75 μ m. For assessment of the sampling process effect on the collected microorganisms, Bacillus thuringiensis was tested at a concentration of about 1.0 × 106 cells per cm3. The viability in the prototype sampler decreased to 78% after 60 min of operation. [ABSTRACT FROM AUTHOR]

Ethylene (C2H4) and bioaerosol are commonly present in the inside atmosphere of postharvest fruit and vegetable storage facilities, which may affect the aging of postharvest fruit and human health. We have assessed the feasibility of chlorine dioxide (ClO2) as the scrubbing solution in a chemical scrubbing tower for simultaneously removing C2H4 and bioaerosol emissions from a gas stream. Parameters such as the ClO2concentration, contact time, and liquid-to-gas (L/G) ratio were examined with the aim of determining the optimal operating conditions. Using the system reported here, the optimal C2H4 removal efficiency was 99.5% when 500 ppm ClO2 was used at a reaction time of 30-60 s under a continuous non-recycle ClO2 flow mode. In terms of C2H4 removal, a greater L/G resulted in a higher C2H4 removal efficiency up to the optimal ratio of 12.5. In terms of the simultaneous removal of C2H4 and bioaerosol, the removal efficiency of C2H4 was 99.2% and those for the bioaersols of Escherichia coli and Staphylococcus aureus were 99.92 and 99.10%, respectively, under a continuous non-recycle flow mode. Our results also indicate that oxidation reduction potential (ORP) can be a valuable indicator for the timing of the replacement of the scrubbing solution in the system under a continuous recycle flow mode. Additional confirmation of the feasibility of the ORP as an indicator of C2H4 and bioaerosol removal in situ was obtained in a 3-month test of our system in continuous recycle flow mode with the periodical replacement of scrubbing solution, ClO2. The removal efficiencies for C2H4, bacterial and fungus aerosol, and total hydrocarbon compounds (THC) were 83.4, 96.8, 96.1, and 76.5%, respectively. Our results prove that ClO2 is an excellent scrubbing solution in the chemical scrubbing tower for the removal of C2H4 emissions and bioaerosol. We demonstrate, for the first time, the feasibility of this system in a fruit and vegetable storage facility. [ABSTRACT FROM AUTHOR]

The authors performed 3 experiments to measure temporal variation in airborne bacterial and fungal levels associated with the use of air conditioners (ACs), heaters, and humidifiers. The concentrations of bioaerosols that they measured inside vehicles and a seminar room prior to use of an AC were lower than or similar to those for outdoor air. In most cases, elevated concentrations occurred 5 to 15 minutes after the use of an automobile or household AC, and these concentrations decreased over time. For 3 of 5 cars, however, the bacterial concentrations did not vary significantly. For cars, the maximum bacterial concentration (2,550 CFU m-3) was 46 times higher than the in-vehicle background concentration (55 CFU m-3). Three fungi (Cladosporium, Penicillium, and Aspergillus) exhibited the highest concentrations for most sampling periods of the ACs and heater. The use of automobile heaters and household humidifiers could suppress in-vehicle and in-room microbial concentrations. [ABSTRACT FROM AUTHOR]

This study was undertaken to determine the normal indoor and outdoor airborne culturable fungal constituents and concentrations of an arid environment. Air samples were taken with two-stage, ambient, culturable sampler systems and analyzed for nine specific fungal genera from 50 homes as a repeated measure during each season of the year. These homes had no previous histories of indoor air quality issues. This study detected seasonal differences for the arid environment between different culturable fungal concentrations across the two size ranges. The highest concentrations were during fall, in the outdoor fine-size range. The lowest concentrations were the indoor coarse concentrations in the spring. From this study it can be concluded that Cladosporium spp. had the highest concentrations during fall in an arid environment. The overall findings suggest that Cladosporium had concentrations greater than the other genera evaluated, specifically, the fall outdoor fine concentrations. Seasonality was found to be a key factor in determining the variability of fungal constituents and concentrations within the arid indoor and outdoor environments. The fine-size range was 12 times and 6 times greater than the coarse-size range for indoor and outdoor samples, respectively, which accounted for the majority of fungal organisms. In addition, the results from this study in an arid climate differ from those conducted in a moister climate. [ABSTRACT FROM AUTHOR]

A number of interpretive descriptors have been proposed for bioaerosol data due to the lack of health-based numerical standards, but very few have been verified as to their ability to describe a suspect indoor environment. Culturable and nonculturable (spore trap) sampling using the bootstrap version of Monte Carlo simulation (BMC) at several sites during 2003-2006 served as a source of indoor and outdoor data to test various criteria with regard to their variability in characterizing an indoor or outdoor environment. The purpose was to gain some insight for the reliability of some of the interpretive criteria in use as well as to demonstrate the utility of BMC methods as a generalized technique for validation of various interpretive criteria for bioaerosols. The ratio of nonphylloplane (NP) fungi (total of Aspergillus and Penicillium) to phylloplane (P) fungi (total of Cladosporium, Alternaria, and Epicoccum), or NP/P, is a descriptor that has been used to identify "dominance" of nonphylloplane fungi (NP/P > 1.0), assumed to be indicative of a problematic indoor environment. However, BMC analysis of spore trap and culturable bioaerosol data using the NP/P ratio identified frequent dominance by nonphylloplane fungi in outdoor air. Similarly, the NP/P descriptor indicated dominance of nonphylloplane fungi in buildings with visible mold growth and/or known water intrusion with a frequency often in the range of 0.5 Fixed numerical criteria for spore trap data of 900 and 1300 spores/m3 for total spores and 750 Aspergillus/Penicillium spores/m3 exhibited similar variability, as did ratios of nonphylloplane to total fungi, phylloplane to total fungi, and indoor/outdoor ratios for total fungal spores. Analysis of bioaerosol data by BMC indicates that numerical levels or descriptors based on dominance of certain fungi are unreliable as criteria for characterizing a given environment. The utility of BMC analysis lies in its generalized application to test mathematically the validity of any given descriptor or criterion for bioaerosols, which can be an important tool in quantifying the uncertainty in interpreting bioaerosol data. [ABSTRACT FROM AUTHOR]

There is a limited amount of information available on stock farmers' exposure to airborne bacteria and fungi. In this study, the authors measured the airborne bacteria and fungi concentrations 46 times inside two swine sheds and four poultry sheds. Aspergillus, Cladosporium, and Penicillium were the most prevalent fungal genera, as most of the fungi belonged to these groups. Many microbial concentrations exceeded the Korean indoor bioaerosol guideline 800 CFU M-3 (ie, colony-forming units per cubic meter of air). This finding suggests the need for a strategy to reduce stock farmers' occupational exposure to the microorganisms in swine and poultry sheds, and the necessity of performing a longitudinal survey to better examine farmer exposure levels and their variability. Another finding was that the use of a sanitary mask may reduce stock farmers' exposure to bioaerosols. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of two municipal landfills on the microbiological air quality in offices on landfill sites. The evaluation was based on the concentration levels of airborne bacteria and fungi and the identification of isolated strains. Air samples were collected with a six-stage Andersen impactor. The concentrations of bac-terial aerosol ranged from 1.0 x10 3 to 7.2 x10 4 colony form-ing units (CFU)/m 3 indoors, and from 7.0 x10 to 4.0 x10 4 CFU/m 3 outdoors. The corresponding fungal aerosol ranges were from 2.3 x10 2 to 7.3 x10 3 CFU/m 3 indoors and from 2.0 x10 2 to 1.2 x10 4 CFU/m 3 outdoors. The concentration levels were affected by the season of the year. The study showed that both indoor and outdoor air were heavily contaminated with bacteria and fungi. The proximity of the unpaved trans-port route and the weighing of refuse loads contributed to the increase of bacterial and fungal aerosol concentrations significantly. The air in the offices was characterized not only by elevated concentrations of bacteria and fungi but also by high frequencies of gram-negative bacteria, along with fun-gal species characteristic of landfills. The quantitative and qualitative changes in the composition of the bacterial and fungal aerosol posed a possible health risk to office workers at municipal waste landfill sites. [ABSTRACT FROM AUTHOR]

This study was carried out to investigate possible relationship between bio-contaminants and symptoms of sick building syndrome among office workers in Mauritius. Viable microbial colonies were collected using a Casella slit sampler in 23 selected indoor office buildings. A questionnaire survey as well as a walk through investigation was undertaken. Physico-chemical measurements were also monitored in the selected offices. Results of this study showed that number of indoor bacterial bioaerosol concentrations ranged between 3 and 1110 CFU/m[sup 3] while fungal counts were 0-196 CFU/m[sup 3]. However, most of the buildings showed absence of dust mites. In conclusions fungal contamination was found to be associated with the onset of sick building syndrome symptoms among workers in office buildings in Mauritius. [ABSTRACT FROM AUTHOR]

Both the quantity and quality of microorganisms (mold, actinomycetes and bacteria) were investigated in the air of five clean rooms indoors, outdoor air sampling was a routine work of the present study. Total viable bacterial counts were recorded in a mean value of 103 cfu/m3, whereas mold counts ranged between 102-103 cfu/m3. The highest mold counts were recorded at some places investigated such as research laboratories and a library. Moreover, the types, percentages and frequencies of occurance of viable mold were studied. Penicillium, Cladosporium and Aspergillus were the predominant mold genera. These organisms are aeroallergens. Actinomycetes were detected in low numbers compared with other organisms (range between 0-102 cfu/m3). Yellow, grey and white colour series were dominant streptomycetes. The mold and streptomycetes spore sizes were measured microscopically. The sizes of major mold spores ranged between 2.5-10 mum, whereas that of streptomycetes spores ranged between 1.2-2.5 mum. The particles < 5 mum in sizes are likely to reach the alveoli which may elicit potential risk for exposed residents. However, a low number of air microorganisms does not mean a clean and healthy environment. [ABSTRACT FROM AUTHOR]

Nosocomial infections pose an escalating threat to both patients and healthcare workers (HCWs). A widely recommended device for individual respiratory protection, the N95 filtering facepiece respirator (FFR) has been shown to provide efficient filtration of inert particles larger and smaller than the nominal most-penetrating particle size (MPPS) range, 0.03–0.3 μm. Humans generate respiratory aerosols in the MPPS range, suggesting that short-range disease transmission could occur via small infectious particles. Data presented here show that the N95 FFR will afford a significant measure of protection against infectious particles as small as a bare H1N1 influenza virion, and that the capture mechanism does not discriminate in favor of, or against, biological particles. [ABSTRACT FROM PUBLISHER]

In November 1995 the National Institute for Occupational Safety and Health (NIOSH) Denver Field Office received a letter from the City and County of Denver requesting assistance in determining worker and spectator exposures during the National Western Stock Show (NWSS) held in Denver, Colorado, January 6--21, 1996. The exposures of concern were carbon monoxide, carbon dioxide as an indicator of ventilation efficiency, total and respirable dust, free silica, and bioaerosols. [ABSTRACT FROM AUTHOR]