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The properties of bioaerosols are complex and diverse, and have a direct impact on the environment, climate, and human health. The effective identification of bioaerosols in the atmosphere is very significant with regard to accurately obtaining the atmospheric chemical characteristics of bioaerosols. To improve the detection of large particle bioaerosol and non-bioaerosol interference in the process of bioaerosol recognition, this study detected a variety of bioaerosols and abiotic aerosols based on a single particle aerosol mass spectrometer (SPAMS). Furthermore, the bioaerosol particle identification and classification algorithm based on Zawadowicz the ratio of phosphate to organic nitrogen is optimized to distinguish bioaerosols from abiotic aerosols. The influence of ionized laser energy on classification methods is thoroughly explored here. The results show that 15 kinds of pure fungal aerosols were detected by SPAMS based on a wide size range sampling system, and that fungal aerosols with a particle size of up to 10 μm can be detected. Through the mass spectra peak ratio method of PO3−/PO2− and CNO−/CN−, when discriminating abiotic aerosols such as disruptive biomass combustion particles, automobile exhaust, and dust from pure bacterial aerosols, the discrimination degree is up to 97.7%. The optimized ratio detection method of phosphate to organic nitrogen has strong specificity, which can serve as the discriminant basis for identifying bioaerosols in SPAMS analytical processes.

Background Several studies suggest that far-field transmission (>6 ft) explains a significant number of COVID-19 superspreading outbreaks. Objective Therefore, quantifying the ratio of near- and far-field exposure to emissions from a source is key to better understanding human-to-human airborne infectious disease transmission and associated risks. Methods In this study, we used an environmentally-controlled chamber to measure volatile organic compounds (VOCs) released from a healthy participant who consumed breath mints, which contained unique tracer compounds. Tracer measurements were made at 0.76 m (2.5 ft), 1.52 m (5 ft), 2.28 m (7.5 ft) from the participant, as well as in the exhaust plenum of the chamber. Results We observed that 0.76 m (2.5 ft) trials had ~36–44% higher concentrations than other distances during the first 20 minutes of experiments, highlighting the importance of the near-field exposure relative to the far-field before virus-laden respiratory aerosol plumes are continuously mixed into the far-field. However, for the conditions studied, the concentrations of human-sourced tracers after 20 minutes and approaching the end of the 60-minute trials at 0.76 m, 1.52 m, and 2.28 m were only ~18%, ~11%, and ~7.5% higher than volume-averaged concentrations, respectively. Significance This study suggests that for rooms with similar airflow parameters disease transmission risk is dominated by near-field exposures for shorter event durations (e.g., initial 20–25-minutes of event) whereas far-field exposures are critical throughout the entire event and are increasingly more important for longer event durations. Impact statement We offer a novel methodology for studying the fate and transport of airborne bioaerosols in indoor spaces using VOCs as unique proxies for bioaerosols. We provide evidence that real-time measurement of VOCs can be applied in settings with human subjects to estimate the concentration of bioaerosol at different distances from the emitter. We also improve upon the conventional assumption that a well-mixed room exhibits instantaneous and perfect mixing by addressing spatial distances and mixing over time. We quantitatively assessed the exposure levels to breath tracers at alternate distances and provided more insights into the changes on “near-field to far-field” ratios over time. This method can be used in future to estimate the benefits of alternate environmental conditions and occupant behaviors.

Se realizó un monitoreo microbiológico, en cuatro zonas del municipio de Yacopí; el Ancianato, las Instituciones Educativas y la Plaza de mercado, con el fin de caracterizar los bioaerosoles causantes de enfermedades respiratorias en las zonas de muestreo. Para la toma de muestras se utilizó el equipo MAS-100 y se registraron las variables ambientales; humedad relativa y temperatura con el termohigrómetro, en la identificación de los microorganismos se usó la tinción de Gram para las bacterias y la tinción de azul de lactofenol para hongos. Se obtuvo que las zonas con mayor concentración de bioaerosoles fueron la Plaza de mercado y el colegio EDUSAN y los géneros con mayor frecuencia de aparición fueron Staphylococcus y Rhodotorula presentando alto riesgo en la salud de las personas, puesto que, éstas pueden generar enfermedades como asma, neumonía y afectan principalmente el tracto respiratorio. Microbiological monitoring was carried out in four areas of the municipality of Yacopí; the Eldership, the Educational Institutions and the Market Square, in order to characterize the bioaerosols that cause respiratory diseases in the sampling areas. The MAS-100 equipment was used for sampling and the environmental variables were recorded; relative humidity and temperature with the thermohygrometer, in the identification of microorganisms Gram stain was used for bacteria and lactophenol blue stain for fungi. Was obtained, the areas with the highest concentration of bioaerosols were the Market Square and the EDUSAN school, and the genera with the highest frequency of apartition were Staphylococcus and Rhodotorula, presenting a high health risk for people, since they can cause diseases such as asthma, pneumonia and mainly affect the entire respiratory tract. Ingeniero Ambiental Pregrado

This study aimed to assess the markers of chemical and microbiological contamination of the air at sport centers (e.g., the fitness center in Poland) including the determination of particulate matter, CO2, formaldehyde (DustTrak™ DRX Aerosol Monitor; Multi-functional Air Quality Detector), volatile organic compound (VOC) concentration (headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry), the number of microorganisms in the air (culture methods), and microbial biodiversity (high-throughput sequencing on the Illumina platform). Additionally the number of microorganisms and the presence of SARS-CoV-2 (PCR) on the surfaces was determined. Total particle concentration varied between 0.0445 mg m−3 and 0.0841 mg m−3 with the dominance (99.65–99.99%) of the PM2.5 fraction. The CO2 concentration ranged from 800 ppm to 2198 ppm, while the formaldehyde concentration was from 0.005 mg/m3 to 0.049 mg m−3. A total of 84 VOCs were identified in the air collected from the gym. Phenol, D-limonene, toluene, and 2-ethyl-1-hexanol dominated in the air at the tested facilities. The average daily number of bacteria was 7.17 × 102 CFU m−3–1.68 × 103 CFU m−3, while the number of fungi was 3.03 × 103 CFU m−3–7.34 × 103 CFU m−3. In total, 422 genera of bacteria and 408 genera of fungi representing 21 and 11 phyla, respectively, were detected in the gym. The most abundant bacteria and fungi (>1%) that belonged to the second and third groups of health hazards were: Escherichia-Shigella, Corynebacterium, Bacillus, Staphylococcus, Cladosporium, Aspergillus, and Penicillium. In addition, other species that may be allergenic (Epicoccum) or infectious (Acinetobacter, Sphingomonas, Sporobolomyces) were present in the air. Moreover, the SARS-CoV-2 virus was detected on surfaces in the gym. The monitoring proposal for the assessment of the air quality at a sport center includes the following markers: total particle concentration with the PM2.5 fraction, CO2 concentration, VOCs (phenol, toluene, and 2-ethyl-1-hexanol), and the number of bacteria and fungi.

Diurnal variations in the concentrations of culturable fungal and bacterial bioaerosols were measured during winter and spring. Significant variations in concentrations of bacterial bioaerosols were observed during the day in this measurement campaign. The bacterial bioaerosol concentration exhibited two peaks during the morning and evening periods in the winter season. Diurnal variation in bacterial bioaerosols was greater in spring than that in winter. However, fungal bioaerosol concentrations were not affected by diurnal and seasonal changes. Environmental properties such as temperature, relative humidity, and ultraviolet irradiation intensity were measured, and their relationship with bioaerosol concentrations was analyzed. The surrounding temperature was suspected as a significant factor. This diurnal variation in culturable bioaerosols can explain various public health phenomena. Variations in the concentrations of non-biological aerosol particles were also analyzed.

Biosafety laboratory is an important place to study high-risk microbes. In biosafety laboratories, with the outbreak of infectious diseases such as COVID-19, experimental activities have become increasingly frequent, and the risk of exposure to bioaerosols has increased. To explore the exposure risk of biosafety laboratories, the intensity and emission characteristics of laboratory risk factors were investigated. In this study, high-risk microbe samples were substituted with Serratia marcescens as the model bacteria. The resulting concentration and particle size segregation of the bioaerosol produced by three experimental procedures (spill, injection, and sample drop) were monitored, and the emission sources’ intensity were quantitatively analyzed. The results showed that the aerosol concentration produced by injection and sample drop was 103 CFU/m3, and that by sample spill was 102 CFU/m3. The particle size of bioaerosol is mainly segregated in the range of 3.3–4.7 μm. There are significant differences in the influence of risk factors on source intensity. The intensity of sample spill, injection, and sample drop source is 3.6 CFU/s, 78.2 CFU/s, and 664 CFU/s. This study could provide suggestions for risk assessment of experimental operation procedures and experimental personnel protection.

Background: Bacillus Calmette-Guerin (BCG) is a vaccine used to protect against tuberculosis primarily in infants to stop early infection in areas of the world where the disease is endemic. Normally administered as a percutaneous injection, BCG is a live significantly attenuated bacteria that is now being investigated for its potential within an inhalable vaccine formulation. This study investigates the feasibility and performance of two jet and two vibrating mesh nebulizers aerosolizing BCG and the resulting particle characteristics and residual viability of the bacteria postaerosolization. Methods: A jet nebulizer (Collison), outfitted either with a 3- or 6-jet head, was compared with two clinical nebulizers, the vibrating mesh Omron MicroAir and Aerogen Solo devices. Particle characteristics, including aerodynamic particle sizing, was performed on all devices within a common aerosol chamber configuration and comparable BCG innocula concentrations. Integrated aerosol samples were collected for each generator and assayed for bacterial viability using conventional microbiological technique. Results: A batch lot of BCG (Danish) was grown to titer and used in all generator assessments. Aerosol particles within the respirable range were generated from all nebulizers at four different concentrations of BCG. The jet nebulizers produced a uniformly smaller particle size than the vibrating mesh devices, although particle concentrations by mass were similar across all devices tested with the exception of the Aerogen Solo, which resulted in a low concentration of BCG aerosols. Conclusions: The resulting measured viable BCG aerosol concentration fraction produced by each device approximated one another; however, a measurable decrease of efficiency and overall viability reduction in the jet nebulizer was observed in higher BCG inoculum starting concentrations, whereas the vibrating mesh nebulizer returned a remarkably stable viable aerosol fraction irrespective of inoculum concentration.

The aim of this study was to assess bacterial aerosols in a herbal processing plant in Poland. Bioaerosol measurements of indoor and outdoor air of the herbal processing plant were performed in four measurement rounds, in a seasonal cycle—in spring, summer, autumn, and winter—using a six-stage Andersen’s cascade air sampler. At each measuring point, during the bioaerosol sampling, the values of relative humidity and air temperature were simultaneously measured using the Kestrel 4000 device, and the concentration of particulate matter (fractions 1.0 μm, 2.5 μm, 4.0 µm, and 10.0 µm) using a DustTrak II dust analyzer. The results showed that the production process affects the bacterial aerosol concentrations in the tested plant. There were statistically significant differences in the concentrations of bacterial aerosol between indoor and outdoor air, and between production rooms, taking into account the seasons of the year. The concentrations of bacterial aerosol in the production rooms did not exceed 7.6 ×·103 cfu·m−3 and were lower than the permissible concentration values proposed for production rooms contaminated with organic dust. The calculations showed a significant correlation between the concentration of bacterial aerosol and air temperature. Qualitative analysis of microorganisms isolated from the air of production rooms showed the dominance of Gram-positive cocci of the genus Micrococcus and spore-forming rods of the Bacillus genus. The study confirmed that herbal processing plants may be related to exposure to microbiological agents.

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The transmission of hazardous agents via bioaerosols has been long-acknowledged as an important risk, yet it has been poorly studied and understood, due to paltry data, methodological heterogeneity and limitation. Therefore, this thesis mainly chose 2 different kind of hazardous agents: antibiotic resistance genes (ARGs) and human respiratory viruses as examples to attempt to narrow several gaps in bioaerosol research. Antibiotic resistance genes (ARG) have been considered as a global emerging threat to public health systems. As special locations where both antibiotics and ARGs are directly used, biology laboratories are poorly studied but potential important emission sources where not only the environmental stress is strong but also obtaining resistance is much easier comparing to other well studied hot spots including farms, hospitals, wastewater treatment plants and landfills where antibiotics but not ARGs are used or discharged. Therefore, Chapter 2 focused on emission source identification .11 Swiss biology laboratories working on different fields and located in the city center, suburb and rural area were studied to reveal the abundance and diversity of airborne ARGs in them and their surrounding areas with Colony-forming units (CFU) cultivation and quantitative Polymerase Chain Reaction (qPCR). Most biology laboratories did not discharge significant amounts or varieties of ARGs and cultivable bacteria via air. No correlation was found between the number of CFUs and the abundance of 16S rRNA, but two clusters of correlated airborne ARGs, the animal husbandry related cluster, and city and hospital related cluster were identified in this study. Although most biology laboratories may not be the emission sources of a wide variety of airborne ARGs, the ARGs in the animal husbandry related cluster which are abundant in the animal laboratories and aadA1 which is abundant in the laboratories working on other eukaryocytes need to be furtherly studied to make sure if they are potential health risks for the researchers. Another gap in bioaerosol research is methodology standardization. While the pandemic of coronavirus disease 2019 (COVID-19) continues to threaten public health, various primers of reverse transcription quantitative polymerase chain reaction (RT-qPCR) have been swiftly developed. Comparing their performances is very necessary for the optimization and standardization the detection and quantification method to assist the disease control. Furthermore, for developing countries, cheaper alternative molecular methods for SARS-CoV-2 identification can be crucial to prevent the next wave of infections. Therefore, in Chapter 2, we evaluated the 12 primer sets recommended by the World Health Organization (WHO) on testing both clinical patient and environmental samples with the gold standard diagnosis method: TaqMan-based RT-qPCR and a cheaper alternative method: SYBR Green-based RT-qPCR. We found that using suitable primer sets, such as ORF1ab, 2019_nCoV_N1 and 2019_nCoV_N3, the performance of the SYBR Green approach was comparable or even outperformed the TaqMan approach, even when considering the newly dominating or emerging variants, including Delta, Eta, Kappa, Lambda and Mu. ORF1ab and 2019_nCoV_N3 were found to be the best combination for sensitive and reliable SARS-CoV-2 molecular diagnostics due to their high sensitivity, specificity and broad accessibility. Based on the results of Chapter 2, we furtherly collected outdoor airborne particulate matter (PM) samples from November 2019 to April 2020 in Bern, Lugano, and Zurich to study the correlations between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory viruses, between viruses and environmental factors, and between viruses and human behavior changes due to the public health measures against COVID-19. Because similar studies are scarce on air surveillance of the virus in outdoor non-healthcare environments which is also a current gap of the understanding of viral bioaerosols, although virus-laden particles have been commonly detected and studied in the aerosol samples from indoor healthcare settings. Among 14 detected viruses, influenza A, HCoV-NL63, HCoV-HKU1, and HCoV-229E were abundant in air. SARS-CoV-2 and enterovirus were moderately common, while the remaining viruses occurred only in low concentrations. SARS-CoV-2 was detected in PM10 (PM below 10 µm) samples of Bern and Zurich, and PM2.5 (PM below 2.5 µm) samples of Bern which exhibited a concentration positively correlated with the local COVID-19 case number. The concentration was also correlated with the concentration of enterovirus which raised the concern of coinfection. The estimated COVID-19 infection risks of an hour exposure at these two sites were generally low but still cannot be neglected. This study demonstrated the potential functionality of outdoor air surveillance of airborne respiratory viruses, especially at transportation hubs and traffic arteries. However, there is no available detection and quantification method capable of fast, sensitive, specific and convenient onsite measuring for air surveillance and risk alarming. CRISPR diagnostics systems are potential candidates because they are fast and specific. Yet, current CRISPR diagnostics are either moderate sensitive enough or supersensitive, and rely heavily on pre-amplification which hinders their potential for quantification. To overcome this limitation, in Chapter 4, a new ultrasensitive CRISPR-Cas based nucleic acid detection system, named Paired-CRISPR-Cas-Only Identification Relay Origination Technique (POIROT) was developed to enable CRISPR-Cas12 cascade the signal to CRISPR-Cas13 for nucleic acid detection. The system was tested with two different DNA targets: the viral DNA of human monkey pox virus and floR, an antibiotic resistance gene against florfenicol. This system has an impressive low limit of detection (LoD) of 1 copy/μl and a short responding time of 15 minutes. The system has potential for use in both diagnosis and environmental surveillance, and may provide new insights into the forms of DNAs in the environment. While the system has some limitations that need to be addressed, it offers promising potential for the development of high-performance artificial nucleic acid detection methods with CRISPR-Cas, particularly in environmental surveillance. The findings in this thesis have improved the understanding of bioaerosols from several angles, and offered potential choices to narrow the gaps in bioaerosol research, paving the ways for future. These advancements can help scientists, public health planners, policymakers, and regulators to improve the air quality, and protecting the environment, and also provide suggestions and warnings to the public on self-protection, ultimately contributing to creating healthier conditions on our habitable planet together from both sides.

BackgroundSpore Trap is an environmental detection technology, already used in the field of allergology to monitor the presence and composition of potentially inspirable airborne micronic bioparticulate. This device is potentially suitable for environmental monitoring of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in hospital, as well as in other high-risk closed environments. The aim of the present study is to investigate the accuracy of the Spore Trap system in detecting SARS-CoV-2 in indoor bioaerosol of hospital rooms.MethodsThe Spore Trap was placed in hospital rooms hosting patients with documented SARS-CoV-2 infection (n = 36) or, as a negative control, in rooms where patients with documented negativity to a Real-Time Polymerase Chain Reaction molecular test for SARS-CoV-2 were admitted (n = 10). The monitoring of the bioaerosol was carried on for 24 h. Collected samples were analyzed by real-time polymerase chain reaction.ResultsThe estimated sensitivity of the Spore Trap device for detecting SARS-CoV-2 in an indoor environment is 69.4% (95% C.I. 54.3-84.4%), with a specificity of 100%.ConclusionThe Spore Trap technology is effective in detecting airborne SARS-CoV-2 virus with excellent specificity and high sensitivity, when compared to previous reports. The SARS-CoV-2 pandemic scenario has suggested that indoor air quality control will be a priority in future public health management and will certainly need to include an environmental bio-investigation protocol.

Background The global shift toward greener societies demands new technologies and work operations in the waste-management sector. However, progressive industrial methods do not necessarily consider workers’ health. This study characterized workers' exposure to bioaerosols and investigated the bioaerosols’ potential to engage the immune system in vitro. Methods Full shift personal aerosol sampling was conducted over three consecutive days. Dust load was analyzed by gravimetry, fungal and actinobacterial spores were analyzed by scanning electron microscopy, and endotoxin by limulus amebocyte lysate (LAL) assay. In vitro exposure of HEK cells to airborne dust samples was used to investigate the potential of inducing an inflammatory reaction. Results The total dust exposure level exceeded the recommended occupational exposure limit (OEL) of 5.0 mg/m3 in 3 out of 15 samples. The inhalable endotoxin level exceeded the recommended exposure level by a 7-fold, whereas the fungal spore level exceeded the recommended exposure level by an 11-fold. Actinobacterial spores were identified in 8 out of 14 samples. In vitro experiments revealed significant TLR2 activation in 9 out of 14 samples vs. significant TLR4 activation in all samples. Conclusion The present study showed that the dust samples contained potentially health-impairing endotoxin, fungi, and actinobacterial levels. Furthermore, the sampled dust contained microbial components capable of inducing TLR activation and thus have the potential to evoke an inflammatory response in exposed individuals.

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Exposure to bioaerosols in enclosed livestock facilities have been reported to pose health risks to workers and animals. Environment-friendly methods for reducing bioaerosol levels in enclosed animal production units could provide important environmental control options. In this study, laboratory-scale electrospray modules were developed to generate engineered water nanostructures (EWNS) to inactivate microbes. The EWNS were generated using three spray liquids (reverse osmosis (RO) water, saline water, and NaOH solution). The physicochemical properties (size, lifetime, reactive oxygen species (ROS) content) of the generated EWNS were characterised. Results showed that the average diameter of the EWNS droplets ranged from 40 to 45 nm. It was found that approximately 17% of the generated EWNS was still present after 4.5 h, and that the most predominant ROS generated was OH·. Furthermore, the efficacy of the generated EWNS in inactivating Escherichia coli was assessed under conditions relevant to livestock facilities. The electrospray modules were installed in an acrylic chamber, which was used to simulate the airspace in an animal barn. After 60-min treatment, reductions in E. coli concentrations inside the chamber were 69%, 64%, and 50% using RO water, saline water, and NaOH solution, respectively, at a ventilation rate of seven air changes per hour (ACH). At 15 ACH, the efficacy of the EWNS generated using RO water was 37%. The results show the potential of the EWNS technology as a microbial decontamination method for animal confinement buildings; however, in-barn tests are necessary before it can be fully implemented in commercial livestock barns.

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 thermo...

Microbial toxins pose a significant threat to the natural environment and all forms of life on planet earth. These biological organisms, such as enzymes, viruses or fragments wreak havoc on the environment and pose a health risk. Toxicity from bioaerosols has a negative impact on human life, causing acute adverse reactions, various types of illnesses, and carcinogenic disorders, among other issues. Although various aspects of bioaerosols have been studied, such as identification, quantification, dispersion, and epidemiology, bioaerosol research is still in its infancy, particularly in terms of understanding anthropogenic behavior. Most of the studies identify the negative impact of bioaerosols, albeit epidemiological evidence remains equivocal. Further, the regulatory enactments and legislative mechanisms for bioaerosol surveillance have yet to be implemented ineffectively in both developed and developing countries. In this overview, we evaluate the pathways and challenges of bioaerosols, highlight gaps in bioaerosol epidemiology, and discuss the public health implications of exposure to complex ecosystems. We also provide an overview of the current state of bioaerosol research, including sampling and enumeration procedures, qualitative and quantitative modeling, global statutory policies, and potential future approaches to addressing the challenges.

Combining wideband integrated bioaerosol sensors and DNA-staining techniques, online and offline shipboard observations of fluorescent aerosol particles in the atmosphere were carried out over the central Pacific Ocean during March 2019 to identify bioaerosols and determine their spatiotemporal distribution. To understand the origins of and processes associated with bioaerosols, we conducted correlation analyses of fluorescent particle number concentration, wind speed, and a variety of chemical and biological indicators, including concentrations of chlorophyll a, bacteria, and marine organic gel particles such as transparent exopolymer particles (TEPs) and Coomassie stainable particles (CSPs). Five-day backward trajectory analysis indicated that oceanic air masses were dominant between 6 and 18 March, after which the influence of long-range transport from the continent of Asia was prominent. For the first period, we identified certain types of fluorescent particles as bioaerosols with marine origins, because their number concentrations were highly correlated with concentrations of TEPs and bacteria (R: 0.80–0.92) after considering the wind speed effect. For the second period, there was strong correlation between another type of fluorescent particles and CSPs irrespective of wind speed, implying that the fluorescent particles advected from land were mixed with those of marine origins. From the results of our correlation analysis, we developed equations to derive atmospheric bioaerosol number density in the marine atmosphere over the central Pacific Ocean from a combination of biogenic proxy quantities (chlorophyll a, TEPs, and bacteria) and wind speed. We conclude that it is likely that TEPs were transported from the sea surface to the atmosphere together with bacteria to form fluorescent bioaerosols.

Understanding the atmospheric concentration of pollen (which is one of the most common vectors of allergens) is necessary to determine the atmospheric allergen level. Airborne pollen concentrations were predominantly evaluated using volumetric and gravitational particle samplers. However, no previous studies have successfully shown whether these sampling methods can be used to evaluate actual airborne pollen concentrations. In this study, the relationship between wind speed and sampling efficiency was investigated to determine whether the influence of ambient wind speed on sampling efficiency was significant. To this end, the influence of wind speed was analyzed by comparing a volumetric sampler and a gravitational sampler. The experimental results indicate that an increase in the wind speed results in an increase in the sampling efficiency of the gravitational sampler because of fluctuations in the turbulence. Our simulation shows that when pollen is entrained in the turbulence, the changes in the wind speed, turbulence amplitude, and turbulence length influence the deposition rate of pollen on the gravitational sampler. These influences can be explained by the turbulence vibration model. These results show the inadequacy of existing evaluation methods, not only for pollen deposition data, but also for all types of bioaerosol deposition data.

Landfill sites are regarded as prominent sources of bioaerosols for the surrounding atmosphere. The present study focused on the emission of airborne bacteria and fungi in four seasons of a sanitary landfill site. The main species found in bioaerosols were assayed using high-throughput sequencing. The SourceTracker method was utilized to identify the sources of the bioaerosols present at the boundary of the landfill site. Furthermore, the health consequences of the exposure to bioaerosols were evaluated based on the average daily dose rates. Results showed that the concentrations of airborne bacteria in the operation area (OPA) and the leakage treatment area (LTA) were in the range of (4684 ± 477)-(10883 ± 1395) CFU/m3 and (3179 ± 453)-(9051 ± 738) CFU/m3, respectively. The average emission levels of fungal aerosols were 4026 CFU/m3 for OPA and 1295 CFU/m3 for LTA. The landfill site received the maximum bioaerosol load during summer and the minimum during winter. Approximately 41.39%- 86.24% of the airborne bacteria had a particle size of 1.1 to 4.7 µm, whereas 48.27%- 66.45% of the airborne fungi had a particle size of more than 4.7 µm. Bacillus sp., Brevibacillus sp., and Paenibacillus sp. were abundant in the bacterial population, whereas Penicillium sp. and Aspergillus sp. dominated the fungal population. Bioaerosols released from the working area and treatment of leachate were the two main sources that emerged in the surrounding air of the landfill site boundary. The exposure risks during summer and autumn were higher than those in spring and winter.

BACKGROUND: The real-world impact of breathing zone air purification and coronavirus disease 2019 (COVID-19) mitigation measures on healthcare-associated infections is not well documented. Engineering solutions to treat airborne transmission of disease may yield results in controlled test chambers or single rooms, but have not been reported on hospital-wide applications, and the impact of COVID-19 mitigation measures on healthcare-associated infection rates is unknown. AIM: To determine the impact of hospital-wide bioaerosol treatment and COVID-19 mitigation measures on clinical outcomes. METHODS: The impact of the step-wise addition of air disinfection technology and COVID-19 mitigation measures to standard multi-modal infection control on particle counts, viral and bacterial bioburden, and healthcare-associated infection rates was investigated in a 124-bed hospital (>100,000 patient-days over 30 months). FINDINGS AND CONCLUSION: The addition of air disinfection technology and COVID-19 mitigation measures reduced airborne ultrafine particles, altered hospital bioburden, and reduced healthcare-associated infections from 11.9 to 6.6 (per 1000 patient-days) and from 6.6 to 1.0 (per 1000 patient-days), respectively (P

Rapid population growth and urbanization process have led to increasing demand for wastewater treatment capacity resulting in a non-negligible increase of wastewater treatment plants (WWTPs) in several cities around the world. Bioaerosol emissions from WWTPs may pose adverse health risks to the sewage workers and nearby residents, which raises increasing public health concerns. However, there are still significant knowledge gaps on the interplay between process-based bioaerosol characteristics and exposures and the quantification of health risk which limit our ability to design effective risk assessment and management strategies. This review provides a critical overview of the existing knowledge of bioaerosol emissions from WWTPs including their nature, magnitude and size distribution, and highlights the shortcoming associated with existing sampling and analysis methods. The recent advancements made for rapid detection of bioaerosols are then discussed, especially the emerging real time detection methods to highlight the directions for future research needs to advance the knowledge on bioaerosol emissions from WWTPs.

The results of the study on the characteristics of the viable (culturable) and total bacterial particles in the ambient air in Gliwice, Poland, are presented. The concentration of viable bacteria in the air ranged from 57 CFU m−3 (Colony Forming Units per cubic meter) during winter to 305 CFU m−3 in spring, while the concentration of all bacteria (live and dead) in the air, measured in selected days, ranged from 298 cells m−3 in winter to over 25 thousand per m3 in autumn. A field study was also carried out to find out the level of the sterilization rate (k) for airborne bacteria. The obtained value of k for viable bacteria exposed to UV solar radiation in Gliwice was approximately 10 cm2 W−1s−1. The patterns of the size distributions of viable bacteria found in three seasons, spring, summer, and autumn, were similar, showing a peak in the range of 3.3–4.7 µm. In the winter season, the main peak was shifted into the smaller particles with an aerodynamic diameter ranging from 2.1 to 4.7 µm. The dominant group of culturable bacteria within the studied period was Gram-positive rods-forming endospores (34–55%), while the least frequent were Gram-negative rods (2%). This research can be used to assess the health effects of exposure to bacterial aerosols in people living in this area.

In the wake of the SARS-CoV-2 pandemic, inactivating bioaerosols became a pivotal issue which helps to prevent the transmittance of SARS-CoV-2. Thus, the current study was conducted to investigate a potential inactivating method using both ozone (O3) and ultraviolet C (UVC). Individual and integrated effects of O3 and UVC were compared. A solution containing approximately 4⁓7.3 × 106 CFU/mL of Salmonella typhimurium bacteria was used to produce bacteria droplets. These droplets were exposed to O3 and UVC to determine the reduction rate of bacteria. The exposure times were set as 1 and 30 minutes. Ozone concentrations were 100 and 200 ppmv. UVC-LEDs were used as a UVC source. Peak wavelength of the UVC-LED was 275 nm and the irradiation dose was 0.77 mW/cm2. In terms of O3 and UVC-LED interaction, 194 ppmv styrene was used as a target compound to be removed. Considering the O3 and UVC-LED interaction, the presence of O3 could reduce the performance of the UVC-LED, and UVC-LED could also reduce significant amount of O3. The sequence of O3 and UVC-LED treatment was as follows: O3 was exposed at first, then UVC-LED, and this order showed the best reduction ratio (≻99.9%). Therefore, if O3 and UVC-LED is used to disinfect Salmonella typhimurium bacteria contained in droplets, bacteria should be separately exposed to O3 and UVC-LED in order to improve the inactivation efficiency. © 2021. by Asian Association for Atmospheric Environment This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.x.

Two cyanobacterial strains, one collected from an epidermal mat present on a dead bottlenose dolphin and the other as a bioaerosol 457 m (1500 ft) above the river, were recently analysed from the S...

Rationale: Severe acute respiratory syndrome caused by coronavirus 2 (SARS-CoV-2) was declared a pandemic on March 11, 2020. Countries entered lockdown, restricting medical activities to essential services. Pulmonary function tests (PFT) are crucial for management of lung diseases. With limited data regarding aerosol generation and the risk of disease transmission during PFTs, many laboratories closed. Our objective is to quantify aerosol generation during different PFT modalities. Methods: We measured aerosol particles in the 0.3-10.0 µm range with an Optical Particle Sizer (Model 3330;TSI Incorporated) and collected bioaerosols to detect respiratory pathogens during clinically indicated PFTs at a hospital-based laboratory during 2 time points in 2020. Results: We monitored 81 and 41 individual multi-modality PFT sessions in June/July and December, respectively. Slow vital capacity, forced vital capacity and diffusion capacity generated higher aerosol counts compared to pre- and post-test room levels although all modalities were lower than during talking or coughing. The aerosol sizes generated were primarily 2.5-10 µm. Oscillometry generated higher overall concentrations than room sampling, also primarily in the 2.5-10 µm aerosols. The bioaerosol filters revealed no respiratory viruses or bacteria. Conclusions: While PFT can generate aerosols, it is less than normal speech with the exception of PFT-induced coughing. Our findings suggest the risk of SARS-CoV-2 transmission is not increased and support the re-opening of PFT laboratories that adhere to universal masking, use of personal protective equipment and stringent infection control protocols. We strongly endorse adherence to public health guidelines in the operation of PFT laboratories.

Real-time onsite monitoring of indoor airborne microbes in a residential property in central Tokyo was carried out in 2020 and 2021, following the onset of the COVID-19 pandemic. A microbial sensor utilizing fluorescence emitted by microorganisms was used to measure bioaerosol concentrations in the living room and children’s bedroom as well as on the balcony. Indoor PM2.5 was also monitored simultaneously at certain time points using a PM2.5 sensor. The behavior of the residents was also recorded during some monitoring periods. The average number concentration of microbes as fungi in the living room was 15,100, 58,800, and 10,600 counts m-3 in spring, summer, and winter, respectively, increasing in summer when the outside temperature was high. Microbial number concentrations were closely related to human behavior, increasing rapidly during periods of physical activity, but decreasing again within 20-30 min of the activity ending. There was no clear correlation between indoor microbial number concentrations and PM2.5 concentrations, suggesting that indoor microorganisms are concentrated in coarse particles, such as dust, which are quickly removed via gravitational settling. The concentration of indoor airborne microorganisms decreased significantly after ventilation, and although an occasional increase was observed immediately after ventilation, concentrations decreased again rapidly within 10-20 min. These results suggest that even a short period of ventilation can significantly reduce the indoor bioaerosol © 2021 by Asian Association for Atmospheric Environment

Exposure to bioaerosols has been identified to be linked the incidence of various health effects, i.e., infectious diseases, acute toxic effects, allergies, and cancer. The aim of this study was to determine the bacterial bioaerosols in the indoor air of the educational environments of Ardabil universities and to evaluate the exposure and to determine its health risk. In this cross-sectional study, different sections of the educational environments of Ardabil universities were studied. For differential diagnosis of bacteria, methods such as gram staining and biochemical detection methods including DNAse, catalase, oxidase, coagulase, bile esculin hydrolysis test, urease, citrate test, antibiotic resistance to novobiocin and Bacitracin, optochin, glucose uptake, and other differential tests were used. For sampling, a single-stage Anderson sampler was used at a flow rate of 28.3 l at a duration of 10 min per minute. The results showed that, in medical school of Ardabil University of Medical Sciences, the average concentration of bacteria in the outdoor air of school, halls, classes and rooms of professors and staff were 18, 88.4, 76.6, and 77.4 CFU/m(3), respectively, and, in Ardabil Islamic Azad University, the average bacterial concentration was 103, 97, 124, and 132 CFU/m(3) in the outdoor air of the schools, halls, classrooms, and rooms of professors and staff, respectively. The predominant bacterial species in indoor air are S. aureus, S. epidermidis, Actinomycetes, and Bacillus, respectively. As results indicated, the concentration of bacterial bioaerosols in indoor air is within the standard levels, but due to frequency of bacterial species, occurrence of different in lung and intestinal diseases can be expected among faculty, staff and students in the long-term.

Limiting infection transmission is central to the safety of all in dentistry, particularly during the current SARS-CoV-2 pandemic. Aerosol-generating procedures (AGPs) are crucial to the practise of dentistry; it is imperative to understand the inherent risks of viral dispersion associated with AGPs and the efficacy of available mitigation strategies.In a dental surgery setting, crown preparation and root canal access procedures were performed with an air turbine or electric speed-controlled hand-piece, with mitigation via rubber dam or high-volume aspiration and a no mitigation control. A phantom head was used with a 1.5 mL flow of artificial saliva infected with Φ6 bacteriophage (a surrogate virus for SARS-CoV-2) at ∼108plaque forming units mL-1, reflecting the upper limits of reported salivary SARS-CoV-2 levels. Bioaerosol dispersal was measured using agar settle plates lawned with the bacteriophage’s host,Pseudomonas syringae. Viral air concentrations were assessed using MicroBio MB2 air sampling, and particle quantities using Kanomax 3889 GEOα particle counters.Compared to an air turbine, the electric hand-piece reduced settled bioaerosols by 99.72%, 100.00% and 100.00% for no mitigation, aspiration and rubber dam, respectively. Bacteriophage concentrations in the air were reduced by 99.98%, 100.00% and 100.00%, with the same mitigation strategies. Use of the electric hand-piece with high-volume aspiration, resulted in no detectable bacteriophage, both on settle plates and in air samples taken 6-10-minutes post-procedure.To our knowledge, this study is the first to report the aerosolization of active virus as a marker for risk determination in the dental setting. Whilst this model represents a worst-case scenario for possible SARS-CoV-2 dispersal, these data showed that the use of electric hand-pieces can vastly reduce the risk of viral aerosolization, and therefore remove the need for clinic fallow time. Furthermore, our findings indicate that the use of particle analysis alone cannot provide sufficient insight to understand bioaerosol infection risk.

BackgroundWorkers of agriculture and intensive life stock farming are exposed to highly contaminated workplaces. Bioaerosol exposures are suspected to trigger respiratory health effects of the workers. So far, risk evaluation of bioaerosols has been assessed through the infectivity of comprising biological agents that is classified in Europe by four risk groups according to the criteria of Directive 2000/54EC of the European Parliament. However, this directive additionally requires the risk assessment of allergenic and toxigenic effects without further elaboration. The aim of our study was to establish an in vitro screening system that is able to measure inhalative toxic effects of bacteria and their metabolites.MethodsIn this study, we analyzed three bacterial toxins and five culture supernatants of selected bacteria with known toxicity as model agents exposed to the lung epithelial cell line NuLi-1. We used electrical cell-substrate impedance sensing (ECIS) method to monitor real-time cell changes and the viability test Prestoblue™.ResultsWe confirmed concentration dependent cytotoxic effects of the selected toxins in NuLi-1 cells over a period of up to 48 h. Each toxin resulted in a different but specific impedance profile over time according to their mode of action, whereas viability assay showed the metabolic activity of the cells at a chosen time point without revealing any information on their mode of action. Furthermore, dose-response-relationships were monitored. Tested model bacteria (Streptoccous pneumoniae, Acinetobacter radioresistens, Aerococcus viridans, Aeromonas hydrophila) reacted according to their expected toxicity except one bacterium (Enterococcus faecalis). The established assays revealed the concentration dependent onset and intensity of bacterial cytotoxicity and the viability of the cells at 24 h and 48 h exposure.ConclusionImpedance measurement and the viability assay Prestoblue™ in combination are suitable as sensitive screening methods to analyze toxic potential of bacteria and can therefor support the risk assessment of workplaces in terms of the directive 2000/54/EC.

Respiratory bioaerosol deposition in public transport cabins is critical for risk analysis and control of contact transmission. In this work, we built a two‐row four‐seat setup and an air duct system to simulate a cabin environment. A thermal manikin on the rear left‐hand seat was taken as the infected passenger (IP) and “coughed” three times through a cough generator. The deposited viruses and droplets on nearby seats were measured by a cultivation method and microscope, respectively. The effects of seat backrest and overhead gasper jet were studied. Results showed that the number of deposited virus on the front seat was one order of magnitude higher than that on other seats which only contained droplets smaller than 10 µm in diameter. When the backrest was 15 cm higher than the cough, the deposited number of viruses was reduced to 5% of that with the backrest at the same height with the cough. The gasper jet above the IP with a velocity of 1.5 m/s can reduce the deposited viruses to 4% of that with gasper off. It indicates that both the gasper jet and backrest can work as mitigation measures to block the cough jet and protect the nearby passengers.

Anaerobic digestion is an emerging technology producing energy from renewable resources or food waste. Exposure screenings, comprising hazardous substances and biological agents, at different workplaces are necessary for a comprehensive overview of potential hazards in order to assess the risk of employees in biogas plants. In order to analyse these parameters, workplace measurements were conducted in seven full-scale anaerobic digesters. Personal and stationary sampling was performed for inhalable and respirable particles, volatile organic compounds, ammonia, hydrogen sulphide, carbon monoxide, and carbon dioxide. Furthermore, concentrations of the total cell count, endotoxins, and fungi—down to species level—were determined in comparison to windward air. Sequencing of the 16S rRNA genes was utilized for the determination of the bacterial composition inside the biogas plants. Measurements of hazardous substances show hardly values reaching the specific occupational exposure limit value, except ammonia. An approximate 5-fold increase in the median of the total cell count, 15-fold in endotoxins, and 4-fold in fungi was monitored in the biogas plants compared with windward air. Specifying the comparison to selected workplaces showed the highest concentrations of these parameters for workplaces related to delivery and cleaning. Strikingly, the fungal composition drastically changed between windward air and burdened workplaces with an increase of Aspergillus species up to 250-fold and Penicillium species up to 400-fold. Sequence analyses of 16S rRNA genes revealed that many workplaces are dominated by the order of Bacillales or Lactobacillales, but many sequences were not assignable to known bacteria. Although significant changes inside the biogas plant compared with windward air were identified, that increase does not suggest stricter occupational safety measures at least when applying German policies. However, exposure to biological agents revealed wide ranges and specific workplace measurements should be conducted for risk assessment.

Although numerous bioaerosol samplers for counting and identifying airborne microorganisms are available, the considerably high purchase and maintenance costs for the sampler often prevent broad monitoring campaigns for occupational or environmental surveillance of bioaerosols. We present here a newly developed simple adapter and filter system (TOP filter system) designed to collect bioaerosol particles from a defined air volume using conventional vacuum cleaners as air pumps. We characterized the physical properties of the system using air flow measurements and validated the biological performance. The culture-based detection capacities for airborne fungal species were compared to a standard impaction sampler (MAS-100 NT) under controlled conditions in a bioaerosol chamber (using Trichoderma spores as the test organism) as well as in the field. In the chamber, an overall equivalent detection capacity between all tested filters was recorded, although a significant underrepresentation of the TOP filter system for Trichoderma spores were seen in comparison to the MAS-100 NT. In a comparative field study (n = 345), the system showed similar biological sampling efficiencies compared to the MAS-100 NT impactor, only the diversity of identified fungal communities was slightly lower on the filters. Thus, the system is suitable for large-scale environmental sampling operations where many samples have to be taken in parallel at a given time at distant locations. This system would allow endeavors such as antibiotics resistance monitoring or hygiene surveys in agricultural or occupational settings.

Occupational exposure to microorganisms can be associated with adverse health outcomes. In this study, we assessed exposure to bioaerosols in two biowaste pretreatment plants in Denmark, which differed in location (city or countryside) and how they were built ('closed-off processes' or 'open processes'). Bioaerosol exposures were characterized by microbial concentrations in personal, stationary, sedimented dust, and hand samples, and their size distribution was assessed. Furthermore, species were identified by matrix-assisted laser desorption-ionisation time-of-flight mass spectrometry (MALDI-TOF MS), and inhalable dust, endotoxin, biofilm production, the total inflammatory potential, and fungicide resistance to four fungicides (amphotericin B, caspofungin acetate, itraconazole, voriconazole) were determined. Bacterial and fungal concentrations were on average (GM) in the order of 104 cfu/m3, but ranged from 102 to 108 cfu/m3. Several species which may cause health problems were identified. Personal endotoxin exposures were on average 28 EU/m3, but both personal and stationary samples ranged from 0.6 to 2035 EU/m3. Bioaerosols had the potential to form biofilms and to induce inflammation as measured in a human cell line. Exposures were higher in the plants that outdoor reference values. Higher exposures were found in the 'open process' plant, such as in microbial concentrations, species richness, endotoxin, biofilm production, and the total inflammatory potential. Six out of 28 tested Aspergillus fumigatus isolates were resistant to fungicides (amphotericin B and voriconazole). In conclusion, there is a high exposure to bioaerosols during work in biowaste pretreatment plants, however, results also suggests that how the plant is built and functions may affect the exposures.

Exposure of microbial agents in the air of indoor dwellings is associated with effects on respiratory and general health. The current study was conducted in the urban area of Delhi Metropolis for the seasonal quantitative assessment of viable microbial indoor air quality. Bioaerosol measurement was conducted by using Anderson six stage impactor with cut-off diameters of 7.0, 4.7, 3.3, 2.1, 1.1, and 0.65 µm) throughout the all the seasons (April 2019 to March 2020). Meteorological parameters such as temperature and relative humidity were measured to check their effect on microbial survival. Air quality index data of the sampling area were recorded by DPCC air quality monitoring system, Ashok Vihar, Delhi. The highest (1654 ± 876.87 CFU/m3) and lowest (738 ± 443.59 CFU/m3) mean bacterial concentration in houses was recorded in August and December, respectively. Similarly, the highest fungal concentration (1275 ± 645.22 CFU/m3) was found in August and the lowest in (776 ± 462.46 CFU/m3) in January. Bacterial respirable fraction shows an irregular pattern in different seasons. In the case of fungi, the respirable fraction of 2.1 and 1.1 contributes more than 60% of total culturable bioaerosols in all seasons. Bacterial genera including Staphylococcus, Micrococcus, and Streptobacillus were most dominant, and Cladosporium, Aspergillus, Penicillium, and Alternaria were the most dominant fungal genera observed indoors. The results of this study suggest that higher respirable fungal fraction might penetrate deeper into the lungs and cause various health effects. A higher concentration of bioaerosols in outdoor areas than indoor shows that the source of indoor bioaerosols is outdoor air. Supplementary Information The online version contains supplementary material available at 10.1007/s10453-021-09718-3.

Bioaerosols are the biological materials in the air, which may cause a continuous threat to human health. However, there are many challenges in monitoring bioaerosols such as lack of sensitivity and selectivity. Herein, we synthesized a series of nanohybrids containing zeolitic imidazolate frameworks (ZIFs) and covalent organic frameworks (COFs) to construct an electrochemical aptasensor for detecting adenosine triphosphate (ATP), a biomarker for bioaerosols. The synthesized nanohybrids can not only improve the selectivity of aptasensor because of the original crystal and chemical features of ZIF-67, but also boost its sensitivity due to the excellent conductivity of COFs. After optimizing the nanohybrids, the novel developed sensing platform achieved highly selective detection of ATP with an excellent detection limit of 0.11 nM in a wide linear range from 0.1 nM to 100 nM. Furthermore, this assay was applied to detect bioaerosols in real air samples, and the result showed a positive correlation with that of the culturing-based method, suggesting its potential applicability.

Embalmers are exposed to many pathogens present in bodily fluids. However, the risk posed by these pathogens has yet to be defined in terms of the nature of the hazard and the intensity of the exposure. The objective of this project was to monitor the exposure of embalmers to biological particles in real time and to characterize the microbiota found in the air during embalming activities in three thanatopraxy laboratories. An innovative approach, using a laser-induced fluorescence aerosol spectrometer (WIBS-NEO), made it possible to measure the concentrations and particle size distributions of the aerosols (biological and non-biological) emitted during embalming. At the same time, an Andersen impactor was used to sample the culturable microbiota present in the air and perform its characterization. The preferential aerosolization of the biological (fluorescent) fraction during embalming procedures, which was compared to the non-biological (non-fluorescent) fraction, showed that most of the tasks performed by the embalmer are likely to lead to microbial exposure via bioaerosols. The concentrations measured represented the equivalent of 2000 to 10,000 biological particles inhaled per minute. Although Mycobacterium tuberculosis was not identified in the air during this study, the presence of Streptococcus pneumoniae in some of the samples demonstrated that if a pathogen is present in the lungs of the deceased it can be aerosolized and inhaled by the embalmers. The size distribution showed that embalmers are exposed to a high proportion of small particles in the aerosols produced during their work. Thus, the respirable/total ratios calculated are between 58% and 78%. Finally, the detection of airborne Enterobacter, Serratia, Leclercia, and Hafnia tended to demonstrate the aerosolization of intestinal bacteria and their possible inhalation or ingestion. Due to the difficulty of identifying the presence of pathogenic agents before embalming, the presence of faecal bacteria in the air, the proximity of the embalmer to the body, and the limitations associated with the dilution of contaminants by general ventilation in the near field, local ventilation must be provided. Otherwise, minimally, a fitted N95-type respirator should be recommended.

The composition and concentration of airborne microorganisms in hospital indoor air has been reported to contain airborne bacteria and fungi concentrations ranged 101–103 CFU/m3 in inpatients facilities which mostly exceed recommendations from the World Health Organization (WHO). In this work, a deeper knowledge of the performance of airborne microorganisms would allow improving the designs of the air-conditioning installations to restrict hospital-acquired infections (HAIs). A solution containing Escherichia coli (E. coli) as a model of airborne bacteria was nebulized using the Collison nebulizer to simulate bioaerosols in various hospital areas such as patients’ rooms or bathrooms. Results showed that the bioaerosol source had a significant influence on the airborne bacteria concentrations since 4.00 102, 6.84 103 and 1.39 104 CFU mL−1 were monitored during the aerosolization for 10 min of urine, saliva and urban wastewater, respectively. These results may be explained considering the quite narrow distribution profile of drop sizes around 1.10–1.29 μm obtained for urban wastewater, with much vaster distribution profiles during the aerosolization of urine or saliva. The airborne bacteria concentration may increase up to 107 CFU mL−1 for longer sampling times and higher aerosolization pressures, causing several cell damages. The cell membrane damage index (ID) can vary from 0 to 1, depending on the genomic DNA releases from bacteria. In fact, the ID of E. coli was more than two times higher (0.33 vs. 0.72) when increasing the pressure of air flow was applied from 1 to 2 bar. Finally, the ventilation air flow also affected the distribution of bioaerosols due to its direct relationship with the relative humidity of indoor air. Specifically, the airborne bacteria concentration diminished almost below 3-logs by applying more than 10 L min−1 during the aerosolization of urine due to their inactivation by an increase in their osmotic pressure., La composición y concentración de los microorganismos transportados por el aire en el interior de los hospitales contiene concentraciones de bacterias y hongos que oscilan entre 101 y 103 UFC/m3 en los centros de hospitalización, que en la mayoría de los casos superan las recomendaciones de la Organización Mundial de la Salud (OMS). En este trabajo, un conocimiento más profundo del comportamiento de los microorganismos transportados por el aire permitiría mejorar los diseños de las instalaciones de aire acondicionado para restringir las infecciones adquiridas en el hospital (HAI). Se nebulizó una solución que contenía Escherichia coli (E. coli) como modelo de bacteria aerotransportada utilizando el nebulizador Collison para simular bioaerosoles en diversas áreas hospitalarias, como las habitaciones o los baños de los pacientes. Los resultados mostraron que la fuente del bioaerosol tenía una influencia significativa en las concentraciones de bacterias aerotransportadas, ya que se monitorizaron 4,00 102, 6,84 103 y 1,39 104 UFC mL-1 durante la aerosolización durante 10 minutos de orina, saliva y aguas residuales urbanas, respectivamente. Estos resultados pueden explicarse considerando el perfil de distribución bastante estrecho de tamaños de gota alrededor de 1,10-1,29 μm obtenido para las aguas residuales urbanas, con perfiles de distribución mucho más amplios durante la aerosolización de orina o saliva. La concentración de bacterias en el aire puede aumentar hasta 107 UFC mL-1 para tiempos de muestreo más largos y presiones de aerosolización más altas, causando varios daños celulares. El índice de daño de la membrana celular (ID) puede variar de 0 a 1, dependiendo de la liberación de ADN genómico de las bacterias. De hecho, el ID de E. coli fue más de dos veces superior (0,33 frente a 0,72) al aumentar la presión del flujo de aire de 1 a 2 bares. Por último, el flujo de aire de ventilación también afectó a la distribución de los bioaerosoles debido a su relación directa con la humedad relativa del aire interior. Concretamente, la concentración de bacterias en el aire disminuyó casi por debajo de 3 logs al aplicar más de 10 L min-1 durante la aerosolización de la orina debido a su inactivación por un aumento de su presión osmótica.

Bioaerosols often contain human pathogens and allergens affecting public health. However, relatively little attention has been given to bioaerosols compared with non-biological aerosols. In this study, we aimed to identify bioaerosol compositions in Manchester, UK by applying high throughput sequencing methods and to find potential sources. Samples were collected at Manchester Air Quality Super Site at the Firs Environmental Research Station in November 2019 and in February 2020. Total DNA has been extracted and sequenced targeting the 16S rRNA gene of prokaryotes, ITS region of fungal DNA and 18S rRNA gene of eukaryotes. We found marine environment-associated bacteria and archaea were relatively more abundant in the February 2020 samples compared with the November 2019 samples, consistent with the North West marine origin based on wind back-trajectory analysis. In contrast, an OTU belonging to Methylobacterium, which includes many species resistant to heavy metals, was relatively more abundant in November 2019 when there were higher metal concentrations. Fungal taxa that fruit all year were relatively more abundant in the February 2020 samples while autumn fruiting species generally had higher relative abundance in the November 2019 samples. There were higher relative abundances of land plants and algae in the February 2020 samples based on 18S rRNA gene sequencing. One of the OTUs belonging to the coniferous yew genus Taxus was more abundant in the February 2020 samples agreeing with the usual pollen season of yews in the UK which is from mid-January until late April. The result from this study suggests a potential application of bioaerosol profiling for tracing the source of atmospheric particles.

Inert particles are widely used as surrogates for biological particles in filtration tests. However, there is always a concern that the different physical properties between inert particles and biological particles may affect the filtration efficiencies of filter media. In the present study, the inert particles, e.g. NaCl and polystyrene latex (PSL), and biological particles, e.g. E.coli, B.sublitis, bovine serum albumin (BSA), and endotoxin, were used to evaluate the filtration efficiencies of the filtering materials of a surgical mask and a N95-rated respirator. The results showed that the difference in the filtration efficiencies of the N95-rated respirator for the tested inert particles and biological particles was smaller than 0.02%. The filtration efficiency of the surgical mask for PSL particles was lower than that for E.coli and B.subtilis particles with the same aerodynamic diameter because of the larger interception lengths of E.coli and B.subtilis particles. The average filtration efficiencies of the surgical mask for the tested NaCl particles and biological particles in the size range of 20–600 nm were similar. For the monodisperse particles, the filtration efficiency of the surgical mask for NaCl, BSA and endotoxin particles in the size range of 50–250 nm decreased in the above order due to the different shapes, dielectric properties, and multiply-charged fractions of the particles. The surgical mask presented the highest filtration efficiency for BSA particles and the lowest filtration efficiency for NaCl particles when the particle size was larger than 300 nm, which could be related to the difference in the electrostatic deposition and bounce probabilities. The present work revealed that the influence of several particle characteristics such as shape, dielectric property, and charge state on filtration efficiency should be considered when using common inert particles to replace biological particles to measure efficiencies of air filters., Separation and Purification Technology, 313, ISSN:1383-5866

Bioaerosols containing pathogenic microorganisms have posed a great threat to human and animal health. Effective monitoring of bioaerosols containing pathogenic viruses and bacteria is of great significance to prevent and control infectious diseases. This Feature summarizes recent advances on bioaerosol collection and detection based on microfluidic chips. Besides, the challenges and trends for bioaerosol collection and detection were also discussed.

Bioaerosols have gained importance in atmospheric sciences in the past few decades. Their exposure upsurges the health problems in sensitive population and is also known to participate in atmospheric chemistry. The present study assesses the monthly distribution of bioaerosol load at four different microenvironments inside an academic institute in Kanpur situated in Indo-Gangetic Plain (IGP). The study duration was from November 2017 to April 2018. The measured total bioaerosol concentrations were highest during April (418–610 CFU/m3) at all sites followed by the post-monsoon month of November (369–577 CFU/m3). The winter period showed low concentrations with lowest concentration obtained in January (251–419 CFU/m3). The indoor–outdoor (I/O) bioaerosol ratio was mostly less than one for bacteria depending on microenvironment, but for fungi it was always less than one. The Gram-positive bacteria (GPB) comprised 70–80% of total bacterial concentration, while Gram-negative bacteria (GNB) contributed 20–30% to bacterial concentration in ambient air. The bacterial genera were mostly dominated by Bacillus, Staphylococcus, Micrococcus, Streptococcus, and Enterococcus, while the fungal genera of Aspergillus, Penicillium, Rhizopus, Cladosporium, Basidiobolus, and Epidermophyton were seen in the campus. The statistical analysis showed a weak positive correlation of bioaerosol concentration with meteorological parameters: temperature and relative humidity (RH).

Summarization: This study presents for the first time comprehensive measurements of the particle number size distribution (10 nm to 10 μm) together with next-generation sequencing analysis of airborne bacteria inside a dental clinic. A substantial enrichment of the indoor environment with new particles in all size classes was identified by both activities to background and indoor/outdoor (I/O) ratios. Grinding and drilling were the principal dental activities to produce new particles in the air, closely followed by polishing. Illumina MiSeq sequencing of 16S rRNA of bioaerosol collected indoors revealed the presence of 86 bacterial genera, 26 of them previously characterized as potential human pathogens. Bacterial species richness and concentration determined both by qPCR, and culture-dependent analysis were significantly higher in the treatment room. Bacterial load of the treatment room impacted in the nearby waiting room where no dental procedures took place. I/O ratio of bacterial concentration in the treatment room followed the fluctuation of I/O ratio of airborne particles in the biology-relevant size classes of 1–2.5, 2.5–5, and 5–10 μm. Exposure analysis revealed increased inhaled number of particles and microorganisms during dental procedures. These findings provide a detailed insight on airborne particles of both biotic and abiotic origin in a dental clinic. Presented on: Indoor Air

Large amounts of bioaerosols are generated during the treatment of landfill leachate, which poses potential threat to public health safety. In this study, the concentrations, particle size distribution, and microbial community of bioaerosols emitted from the low-pH biofilter (LPB) and neutral-pH biofilter (NPB) used to treat the odors from landfill leachate, as well as the effect of the inlet flow rate (IFR) and water-containing rate (WCR) were investigated. The results showed that the removal efficiency of the LPB for heterotrophic bacteria and the NPB for fungi were higher when the IFR was higher. The outlet concentrations (OCs) of heterotrophic bacteria, neutral sulfur bacteria, ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, NO2−, and NO3− were negatively correlated with the IFR in the LPB, whereas those of fungi and acidophilic sulfur bacteria were positively correlated with the IFR. Inverse correlation between the OCs and IFR was exhibited in the NPB. The proportions of dominant microorganisms with large particle size (> 3.3 μm) reduced significantly after both the LPB and NPB, which was aggravated under higher WCR. The analysis of microbial community illustrated that the dominant heterotrophic bacteria were different, while the dominant fungi were similar in the bioaerosols between the LPB and NPB, respectively. Due to the different emission characteristics, bioaerosols in the LPB and NPB outlet should be distinguished and taken seriously.

Due to a large concentration of animals living in a relatively small area, air on pig farms can be contaminated by microorganisms which can have an adverse effect on the health of pigs and farm workers. There is also a possibility of spreading bioaerosol from the farm to the surrounding area which can become a problem for the surrounding populace. Since the concentration of microorganisms in the air around and on the farm can be increased, a microbiological control of indoor and outdoor air is necessary. If the standard values are exceeded, measures of contamination suppression must be taken. To ascertain the microbiological air quality on a pig farm in Slavonia, as well as the changes in the microbiological air quality when moving away from the farm, five samples were taken from the pig farm (nursing ground, feeding ground 1, feeding ground 2, breeding ground, farrowing ground) and four samples were taken 1.5, 5, 10 and 15 meters away from the farm. The sampling was done by impaction, using the SAS SUPER 90 in four iterations (n=36). At the same time, the FLUKE 975V AirMeter device was used to measure the temperature and relative humidity. All air samples were analyzed on a Sabouraud dextrose agar for mold cultivation, as well as on a blood agar for cultivation of aerobic mesophilic bacteria (AMB), and these CFU/m3 values were compared to the standard values ("Diario da Republica n.° 235/2013, 1° Suplemento, Serie I de 2013-12-04"). The number of airborne aerobic mesophilic bacteria on all five farm locations was over the referential value prescribed by the common standards. By moving away from the farm, a drop in the number of airborne AMB was noted. The overall number of indoor air AMB was significantly higher (p>0.05) than in outdoor air. The amount of molds on two farm locations (nursing ground and feeding ground 1) also did not meet the criteria prescribed by the common standards. Just like AMB, a drop in the amount of mold was noted when moving away from the farm. However, there were no notable differences (p>0.05) in their number when comparing indoor and outdoor air.

Graphic abstract In this work, macroscopic TiO2 monoliths are proposed to serve simultaneously as support and co-catalyst in a continuous flow photoreactor. The impregnation via one-pot of mesoporous TiO2 with CdS (m-TiO2/CdS) and CuO (m-TiO2/CuO) nanoparticles enabled the formation of photocatalytic heterojunctions retaining high specific surface area (~ 100 m2/g). The impregnated monoliths of 2–3 mm in size were employed as photocatalysts to inactivate airborne bacteria under blue light, reducing the emission of living airborne bacteria up to 0.1% and 37.7% when using m-TiO2/CdS and m-TiO2/CuO, respectively. Bacteria were characterized and quantified by flow cytometry and cell lysis was confirmed by SEM, detecting collapsed bacteria. Along 96 h of continuous photocatalysis at a flow rate of 2.2 L/min, the cell concentration presented maxima and minima due to the adsorption–desorption stages of bioaerosols over the catalysts, in concordance with thermal gravimetric analysis. The reactivation of catalysts was achieved by calcination at 400 °C, however, after a third re-cycle, the photocatalytic activity for all monoliths was practically negligible because the physicochemical surface changes hinder the adequate bioaerosol adsorption. These porous systems could emerge as promising gas-phase catalysts since the mass transport is facilitated by porosity and the release of catalyst nanoparticles is avoided by the active support, providing a safe and viable model for bioaerosols inactivation to improve indoor air quality with the use of interior lighting. Supplementary Information The online version contains supplementary material available at 10.1007/s10562-021-03659-9.

This study investigated the air quality improvement in terms of bacterial and fungal contamination in an exercise room of a fitness center under normal operating conditions. Environmental conditions including air conditioning, ventilation, moisture, CO2, particulate matters, and total number of users were also recorded. In addition, fungal and bacterial load were assessed and disinfection on sports equipment surface was also examined. Background bacteria and fungi densities in bioaerosols were in the range of 249 ± 65 to 812 ± 111 CFU/m3 and 226 ± 39 to 837 ± 838 CFU/m3 in the exercise room of the fitness center and 370 ± 86 to 953 ± 136 CFU/m3 and 465 ± 108 to 1734 ± 580 CFU/m3 in the outdoor air, respectively. Chlorine dioxide and weak acid hypochlorous water aerosols could remove both bacteria and fungi much better than water scrubbing. Contact time of 15 min was sufficient to control both bacteria and fungi to comply with the official air quality standards. User density and carbon dioxide deteriorated both bacteria and fungi disinfection performance whereas temperature was only statistically significant on fungi disinfection. Other factors including relative humidity, airflow velocity, and particulate matters did not have any statistically significant effect on microbial inactivation. Apart from bioaerosol disinfection, inactivation of microorganisms on surfaces of sports equipment was also conducted using chlorine dioxide, zinc oxide, weak acid hypochlorous water, and commercial disinfectant. The surfaces of bicycle handle, dumbbell, and sit-up bench were found to be contaminated with bacteria. Overall bacterial load was 390 to 3720 CFU/cm2 with Escherichia coli specifically 550 to 1080 CFU/cm2. Chlorine dioxide and zinc oxide were noticeably better than weak acid hypochlorous water and commercial disinfectant in terms of bacteria inactivation whereas all tested disinfectants had comparable effectiveness on E. coli disinfection. Targeted microorganisms on the sports equipment surface were sufficiently inactivated within 2 min after the application of disinfectant.

The present study was carried out to estimate the spatiotemporal variation of fungal bioaerosols, in and around a landfill site in Delhi. The sites were deep in the landfill to nearby residential areas. Fungal bioaerosol sampling was done with the help of Anderson six stage viable cascade impactor on monthly basis for one year from June 2015 to May 2016 at seven different sites in and around the landfill site. The entire sampling period was classified in five different seasons, viz., winter, spring, summer, monsoon and autumn, characteristic of Delhi. It was observed in monsoon season concentration was maximum at most of the sites while lowest during autumn season. Contrary to this, it was also found that concentrations of fine fraction of bioaerosols were significantly high even during autumn at sites deep in the landfill while low in the residential areas near landfill. As such no significant pattern was observed with the coarse fraction of fungal bioaerosols. Typical relations of fungal concentration with the meteorological parameters were also observed. It was noticed that concentration was directly related to temperature and wind speed while inversely related to humidity. Fine and coarse fractions of bioaerosols showed a very good and positive relationship with each other. Among the eight fungal genera identified from the samples of Okhla landfill sites, Penicillium, Aspergillus and Rhizopus were found in abundance at all the seven sites in all the five seasons. Alternaria and Fusarium were found in abundance in spring, summer and winter seasons whereas Cladosporium in autumn and winter. Aspergillussps was present in all the five seasons.

Ragweed pollen is a prevalent allergen in late summer and autumn, worsening seasonal allergic rhinitis and asthma symptoms. In the atmosphere, pollen can osmotically rupture to produce sub-pollen particles (SPP). Because of their smaller size, SPP can penetrate deeper into the respiratory tract than intact pollen grains and may trigger severe cases of asthma. Here we characterize airborne SPP forming from rupturing giant ragweed (Ambrosia trifida) pollen for the first time, using scanning electron microscopy and single-particle fluorescence spectroscopy. SPP ranged in diameter from 20 nm to 6.5 μm. Most SPP are capable of penetrating into the lower respiratory tract, with 82% of SPP $${n}_{\mathrm{f}}$$ n f ) based upon the principle of mass conservation. We estimate that one giant ragweed pollen grain generates 1400 SPP across the observed size range. The new measurements and method presented herein support more accurate predictions of SPP occurrence, concentration, and air quality impacts that can help to reduce the health burden of allergic airway diseases. Graphic abstract Rupturing ragweed pollen releasing cellular components (right), viewed by an inverted light microscope.

Graphical abstract, Highlights • Inertial migration of aerosol particles in a 3D straight microchannel was simulated. • Forces acting on the particle in the air–particle system are analyzed. • Two unstable and four stable equilibrium positions in the air–particle system. • High Reynolds number causes particle oscillation near equilibrium position., In recent years, manipulation of particles by inertial microfluidics has attracted significant attention. However, most studies focused on inertial focusing of particles suspended within liquid phase, in which the ratio of the density of the particle to that of the medium is O(1). The investigation on manipulation of aerosol particles in an inertial microfluidics is very limited. In this study, we numerically investigate the aerosol particle's motion in a 3D straight microchannel with rectangular cross section by fully resolved simulation of the particle–air flow. The air flow is modeled by the Navier-Stokes equations. The particle's motions, including translation and rotation, are governed, respectively, by the Newton's second law and the Euler equations without using any approximation models for the lift and drag forces. The coupled mathematical model is numerically solved by combining immersed boundary with lattice Boltzmann method (IB-LBM). We find that the Reynolds number (Re), the particle's initial position, particle's density and diameter are the influential parameters in this process. The equilibrium positions and their stabilities of aerosols are different from those suspended in liquid.

Aerosol transmission constitutes one of the major transmission routes of the SARS-CoV-2 pathogen. Due to the pathogen’s properties, research on its airborne transmission has some limitations. This paper focuses on silica nanoparticles (SiO2) of 40 and 200 nm sizes as the physicochemical markers of a single SARS-CoV-2 particle enabling experiments on the transmission of bioaerosols in public spaces. Mixtures of a determined silica concentration were sprayed on as an aerosol, whose particles, sedimented on dedicated matrices, were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Since it was not possible to quantitatively identify the markers based on the obtained images, the filters exposed with the AirSampler aspirator were analyzed based on inductively coupled plasma optical emission spectroscopy (ICP-OES). The ICP-OES method enabled us to determine the concentration of silica after extracting the marker from the filter, and consequently to estimate the number of markers. The developed procedure opens up the possibility of the quantitative estimation of the spread of the coronavirus, for example in studies on the aerosol transmission of the pathogen in an open environment where biological markers—surrogates included—cannot be used.