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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.

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.

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.

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

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.

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.

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.

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.

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.

The COVID-19 pandemic pushed dental health officials around the world to reassess and adjust their existing healthcare practices. As studies on controlled COVID-19 transmission remain challenging, this review focuses on particles that can carry the virus and relevant approaches to mitigate the risk of pathogen transmission in dental offices. This review gives an overview of particles generated in clinical settings and how size influences their distribution, concentration, and generation route. A wide array of pertinent particle characterization and counting methods are reviewed, along with their working range, reliability, and limitations. This is followed by a focus on the effectiveness of personal protective equipment (PPE) and face shields in protecting patients and dentists from aerosols. Direct studies on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are still limited, but the literature supports the use of masks as an important and effective non-pharmaceutical preventive measure that could reduce the risk of contracting a respiratory infection by up to 20%. In addition to discussing about PPE used by most dental care professionals, this review describes other ways by which dental offices can protect patients and dental office personnel, which includes modification of the existing room design, dental equipment, and heating, ventilation, and air conditioning (HVAC) system. More affordable modifications include positioning a high-efficiency particulate air (HEPA) unit within proximity of the patient's chair or using ultraviolet germicidal irradiation in conjunction with ventilation. Additionally, portable fans could be used to direct airflow in one direction, first through the staff working areas and then through the patient treatment areas, which could decrease the number of airborne particles in dental offices. This review concludes that there is a need for greater awareness amongst dental practitioners about the relationship between particle dynamics and clinical dentistry, and additional research is needed to fill the broad gaps of knowledge in this field.

Purpose This study was to evaluate the occupational health risks of infection from Gram-negative bacteria and Staphylococcus aureus bioaerosols to temporary entrants and staffs equipped with various grade personal protection equipment (PPE) related to wastewater treatment plants (WWTPs). Methods This study determined the emission concentrations of Gram-negative bacteria and Staphylococcus aureus bioaerosols from two WWTPs under various aeration modes. Then, a strict quantitative microbial risk assessment (QMRA) was performed on several exposure scenarios associated with occupational health risks of temporary entrants (researchers, visitors, and inspectors) and staffs (field engineer and laboratory technician). Results Although the bioaerosol concentrations were generally regarded as safe according to existing standards, these bioaerosols’ health risks were still unacceptable. The microbial bioaerosols posed considerable infection health risks in WWTPs. These risks were generally above the WHO and US EPA benchmarks. The health risks of females were always smaller than those of male of grown-up age group. Staffs that had been exposed to bioaerosols for a long time were found to have higher health risks compared with temporary entrants. In addition, field engineers equipped with PPE rendered low health risks, thus revealing that wearing PPE could effectively reduce the occupational health risks. Conclusion This study provided novel data and enriched the knowledge of microbial bioaerosol emission’s health risks from various aeration modes in WWTPs. Management decisions could be executed by authorities on the basis of the results of QMRA for field engineers equipped with PPE to reduce the related occupational health risks. Supplementary Information The online version contains supplementary material available at 10.1007/s00420-021-01663-5.

PURPOSE: To examine associations between indoor airborne microbial concentration and dry eye (DE) measures. DESIGN: Prospective, observational, cross-sectional study. METHODS: A total of 157 individuals with normal external ocular anatomy were recruited from the Miami Veterans Affairs eye clinic. Subjects underwent a clinical evaluation that included assessment of DE symptoms and signs. Indoor air was sampled using bioaerosol impactors with nutrient and soy media, and samples were incubated for 48 hours at 37 C with 5% CO(2). Number of microbial colonies (CFU) was recorded. Outcome measures were DE symptoms and signs. RESULTS: A total of 157 unique subjects participated in home and clinical visits and of these, 93 completed a 6-month follow-up of home and clinical visits. Older homes were found to have higher CFU compared to newer homes. A 1% increase in humidity was associated with a 3% increase in nutrient CFU (95% confidence interval [CI] = 0.01 to 0.04; P < .001). Instrumented CFU significantly associated with 2 DE measures: corneal epithelial disruption and lower eyelid meibomian gland (MG) dropout, adjusted for age and sex (odds ratio [OR] = 28.07, 95% CI = 1.8, 443.8, P < .05; OR = 39.6, CI = 1.8, 875.2, P < .05 for soy, respectively). After adjusting for other confounders, CFU and age remained significantly associated with MG dropout. Other DE measures did not significantly associate with CFU. CONCLUSIONS: Individuals with higher CFU counts in the home had more severe MG dropout, after adjusting for age and other confounders. This finding suggests that home CFU exposure may impact MG dropout, one of the DE measures, and may be a target for intervention.

Based on the current knowledge of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) transmission, wearing a mask has been recommended during the COVID-19 pandemic. Bacterial filtration efficiency (BFE) measurements enable designing and regulating medical masks to prevent bioaerosol dissemination; however, despite the simplicity of these measurements, several scientific questions remain unanswered regarding BFE tests. Here, we investigated (1) the impact of substituting 100-mm Petri dishes with 90-mm disposable Petri dishes, (2) the impact of colony-counting methods on the bioaerosol aerodynamic size, and (3) the impact of colony-counting methods on the total viable particle counts. We demonstrated that disposable 90-mm Petri dishes can be used to replace the 100-mm dishes. We also showed that an automatic high-resolution colony counter can be used to directly count viable particles on collection substrates and to measure the bioaerosol size parameters. Our results enable possible modernization of the outdated testing methods recommended in the US and European standards for BFE measurements. Specifically, use of a modernized colony counter should be clearly regulated and permitted to avoid the counting of positive holes. The median aerodynamic diameter appears to be the most relevant parameter for characterizing bioaerosol size.

Bacterial and fungal bioaerosols are a global concern due to nosocomial infections, especially in developing countries. Our study aimed to detect fungal and bacterial bioaerosols in different wards of an obstetrics and gynecology hospital air samples. 240 bioaerosol samples were collected by performing impaction method from different wards of a hospital in the central part of Iran, during two seasons. Fungi genera and bacteria species are recognized by cultivation. Concentrations of bacteria and fungi were ranged from 44 to 75 CFU/m3 and 8 to 22 CFU/m3, respectively. Labor Delivery and Recovery (LDR) and Emergency room had first and second most contaminated air among all the hospital wards. No significant difference between microbial load of wards which used natural ventilation and heating, ventilating, and air conditioning (HVAC) system was observed. The microbial load was not affected significantly by temperature, working shift, and Inpatient Bed Occupancy Rate (IBOR). Fungal load related significantly with relative humidity. Staphylococcus aureus (detected in 48.3% of samples) and Penicillium (27%) were the most predominant isolated bacteria and fungi, respectively. The results revealed that the level of bacteria and fungi responsible for nosocomial infections in the air of this hospital is very low. Although levels of microbial contamination are relatively low, it is important to investigate the effect of bioaerosols on nosocomial infections, especially in neonates.

A short distance between infected persons and exposed persons can probably result in a high risk of respiratory infection. This work experimentally investigated the short-range bioaerosol depositio...

Background Previous research has shown that rooms of patients with coronavirus disease 2019 (COVID-19) present the potential for healthcare-associated transmission through aerosols containing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, data on the presence of these aerosols outside of patient rooms are limited. We investigated whether virus-containing aerosols were present in nursing stations and patient room hallways in a referral center with critically ill COVID-19 patients. Methods Eight National Institute for Occupational Safety and Health BC 251 2-stage cyclone samplers were set up throughout 6 units, including nursing stations and visitor corridors in intensive care units and general medical units, for 6 h each sampling period. Samplers were placed on tripods which held 2 samplers positioned 102 cm and 152 cm above the floor. Units were sampled for 3 days. Extracted samples underwent reverse transcription polymerase chain reaction for selected gene regions of the SARS-CoV-2 virus nucleocapsid and the housekeeping gene human RNase P as an internal control. Results The units sampled varied in the number of laboratory-confirmed COVID-19 patients present on the days of sampling. Some of the units included patient rooms under negative pressure, while most were maintained at a neutral pressure. Of 528 aerosol samples collected, none were positive for SARS-CoV-2 RNA by the estimated limit of detection of 8 viral copies/m3 of air. Conclusions Aerosolized SARS-CoV-2 outside of patient rooms was undetectable. While healthcare personnel should avoid unmasked close contact with each other, these findings may provide reassurance for the use of alternatives to tight-fitting respirators in areas outside of patient rooms during the current pandemic., 528 aerosol samples collected from hospital nursing stations, patient room hallways, and visitor corridors in general medical units and intensive care units were negative by RT-PCR for SARS-CoV-2 genetic material. These results have implications for use of personal protective equipment in nonpatient care areas of healthcare facilities

This study assessed the effects of bioaerosol pollution on community health across six urban and residential communities located in Ho Chi Minh megacity, Vietnam. A questionnaire survey was performed on 300 respondents to record health complaints from exposure to bioaerosols. The health symptoms (i.e. flu and cough) were highest in those items with means equal to 6.518 (SD=2.5068) and 6.555 (SD=2.6696), whereas the lowest item was chest tightness with mean equal to 3.334 (SD = 2.7001). The results showed that the questionnaire retained good internal consistency with Cronbach s alpha was 0.613. Using principle component analysis, we have identified 12 questions related to health complaints that could be grouped into five main clusters: PC1 named nose symptoms ; PC2 named throat (respiratory symptoms) ; PC3 named fever symptoms ; PC4 named flu (flu-like symptoms) ; and PC5 named cough symptoms , respectively. The results indicated the potential effects of bioaerosols on human health, with the PCs have accounted for 63.2 percent of the overall total variance and with eigenvalues equal to 1.502 >1. Using multiple linear regression models, this study found that latent factors (i.e. daily habit, living environment, and medical history) such as duration from last pain, residential duration, duration staying at home, home time, distance to street can explain the effect of bioaerosols on health symptoms at the 0.05 significance level. The findings are helpful and significant reference for urban planning, policy making and the community health protection in Ho Chi Minh megacity.

COVID-19 can cause serious respiratory complications resulting in the need for invasive ventilatory support and concurrent aerosol therapy. Aerosol therapy is considered a high risk procedure for the transmission of patient derived infectious aerosol droplets. Critical-care workers are considered to be at a high risk of inhaling such infectious droplets. The objective of this work was to use noninvasive optical methods to visualize the potential release of aerosol droplets during aerosol therapy in a model of an invasively ventilated adult patient. The noninvasive Schlieren imaging technique was used to visualize the movement of air and aerosol. Three different aerosol delivery devices: (i) a pressurized metered dose inhaler (pMDI), (ii) a compressed air driven jet nebulizer (JN), and (iii) a vibrating mesh nebulizer (VMN), were used to deliver an aerosolized therapeutic at two different positions: (i) on the inspiratory limb at the wye and (ii) on the patient side of the wye, between the wye and endotracheal tube, to a simulated intubated adult patient. Irrespective of position, there was a significant release of air and aerosol from the ventilator circuit during aerosol delivery with the pMDI and the compressed air driven JN. There was no such release when aerosol therapy was delivered with a closed-circuit VMN. Selection of aerosol delivery device is a major determining factor in the release of infectious patient derived bioaerosol from an invasively mechanically ventilated patient receiving aerosol therapy.

The fast spread of coronavirus disease 2019 (COVID‐19) constitutes a worldwide challenge to the public health, educational and trade systems, affecting the overall well‐being of human societies. The high transmission and mortality rates of this virus, and the unavailability of a vaccine or treatment, resulted in the decision of multiple governments to enact measures of social distancing. Such measures can reduce the exposure to bioaerosols, which can result in pathogen deposition in the respiratory tract of the host causing disease and an immunological response. Thus, it is important to consider the validity of the proposal for keeping a distance of at least 2 m from other persons to avoid the spread of COVID‐19. This work reviews the effect of aerodynamic diameter (size) of particles carrying RNA copies of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). A SARS‐CoV‐2 carrier person talking, sneezing or coughing at distance of 2 m can still provide a pathogenic bioaerosol load with submicron particles that remain viable in air for up to 3 h for exposure of healthy persons near and far from the source in a stagnant environment. The deposited bioaerosol creates contaminated surfaces, which if touched can act as a path to introduce the pathogen by mouth, nose or eyes and cause disease.

Background During medical procedures with the potential to produce aerosols such as bronchoscopy, intubation or cardiopulmonary resuscitation, healthcare workers (HCWs) may be exposed to infectious bioaerosols. This is of particular concern when high consequence pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are circulating. Thus far thousands of HCWs have been infected, 14.8% of these have severe disease and several have died1. However, the determinants of aerosol generation during such procedures and their relative risk to HCWs remain poorly characterized. Research Question. We sought to characterize aerosols produced during airway intubation using an uninfected translational animal model and in human subjects undergoing elective aerosol-generating procedures. We also determined the particle size distribution of generated particles. Study Design and Methods. Aerosol generation was measured during highly controlled experimental (pig) intubations (N=16) and elective bronchoscopies in uninfected patients (N=49) using an optical particle counter (OPC). Recovery of normal respiratory flora was used as a surrogate for pathogen dispersion. Results There was a small but significant (p = 0.03) decrease in 0.3 μm particles during highly controlled pig intubations compared to baseline. The concentration of 1.0 μm and 5.0 μm aerosol particles did not significantly change though oral bacteria were collected from the air. For elective patient bronchoscopies, there was a significant decrease in the generation of larger particles (1.0 μm and 5.0 μm) compared to baseline (p < 0.01), however, 18 of 39 (46%) of patients showed increased aerosol production in 0.3 μm sized particles, 4 of whom demonstrated significant increases. Interpretation. While the total amount of aerosols produced during intubation and bronchoscopy did not increase significantly relative to pre-procedural levels, a small number of participants showed a significant increase in submicron particle emission, meriting further research to delineate determinants of fine particle production during aerosol-generating procedures.

Background In the COVID-19 crisis, laparoscopic surgery is in focus as a relevant source of bioaerosol release. The efficacy of electrostatic aerosol precipitation (EAP) and continuous aerosol evacuation (CAE) to eliminate bioaerosols during laparoscopic surgery was verified. Study design Ex-vivo laparoscopic cholecystectomies (LCs) were simulated ± EAP or CAE in Pelvitrainer equipped with swine gallbladders. Release of bioaerosols was initiated by performing high-frequency electrosurgery with a monopolar electro hook (MP-HOOK) force at 40 watts (MP-HOOK40) and 60 watts (MP-HOOK60), as well as by ultrasonic cutting (USC). Particle number concentrations (PNC) of arising aerosols were analyzed with a condensation particle counter (CPC). Aerosol samples were taken within the Pelvitrainer close to the source, outside the Pelvitrainer at the working trocar, and in the breathing zone of the surgeon. Results Within the Pelvitrainer, MP-HOOK40 (6.4 × 105 cm-3) and MP-HOOK60 (7.3 × 105 cm-3) showed significantly higher median PNCs compared to USC (4.4 × 105 cm-3) (p = 0.001). EAP led to a significant decrease of the median PNCs in all 3 groups. A high linear correlation with Pearson correlation coefficients of 0.852, 0.825, and 0.759 were observed by comparing MP-HOOK40 (± EAP), MP-HOOK60 (± EAP), and USC (± EAP), respectively. During ex-vivo LC and CAE, significant bioaerosol contaminations of the operating room occurred. Ex-vivo LC with EAP led to a considerable reduction of the bioaerosol concentration. Conclusions EAP was found to be efficient for intraoperative bioaerosol elimination and reducing the risk of bioaerosol exposure for surgical staff., Graphical abstract

The occupational bioaerosols containing viruses, bacteria, fungi, microbial toxins and plant or animal particles, may evoke infectious, allergic or immunotoxic diseases which may co-exist as comorbidities with COVID-19 and exacerbate the course of disease. They include hypersensitivity pneumonitis (HP) caused mostly by bacteria, fungi, and particles containing animal proteins, and immunotoxic diseases such as organic dust toxic syndrome (ODTS) and byssinosis, caused mostly by bacterial and fungal toxins. The two most probable scenarios of possible interrelations between these three comorbidities (CM) and COVID-19 are: 1) 'Triggering' - when infection with SARS-CoV-2 triggers severe CM after bioaerosol exposure; 2) 'Reverse triggering' when exposure to bioaerosol exacerbates a symptomless or mild course of COVID-19, and evokes a severe disease. The occupations mostly endangered by COVID-19 as the result of exposure to SARS-CoV-2 bioaerosol, or to other bioaerosols which may exacerbate this disease, include: health care workers, social workers, breeders of fur animals, slaughterhouse workers, workers engaged in the processing and selling of seafood, and probably also agricultural workers, mainly in the developing countries. The authors present a hypothesis for the origin of the present pandemic. It assumes that a mild form of the present SARS-CoV-2 that is supposedly circulating among the Chinese population in the eastern part of the country, mutated under the influence of as yet unknown factor(s) present in the Chinese seafood markets, probably component(s) of bioaerosols, into the virulent and highly contagious form, known as the present SARS-CoV-2, under a scenario similar to that the authors have named 'Reverse triggering'.

Observations of the long-range transport of biological particles in the tropics via dust vectors are now seen as fundamental to the understanding of many global atmosphere–ocean biogeochemical cycles, changes in air quality, human health, ecosystem impacts, and climate. However, there is a lack of long-term measurements quantifying their presence in such conditions. Here, we present annual observations of bioaerosol concentrations based on online ultraviolet laser-induced fluorescence (UV-LIF) spectrometry from the World Meteorological Organization – Global Atmospheric Watch (WMO-GAW) Cape Verde Atmospheric Observatory on São Vicente. We observe the expected strong seasonal changes in absolute concentrations of bioaerosols with significant enhancements during winter due to the strong island inflow of air mass, originating from the African continent. Monthly median bioaerosol concentrations as high as 45 L−1 were found with 95th percentile values exceeding 130 L−1 during strong dust events. However, in contrast, the relative fraction of bioaerosol numbers compared to total dust number concentration shows little seasonal variation. Mean bioaerosol contributions accounted for 0.4 ± 0.2 % of total coarse aerosol concentrations, only rarely exceeding 1 % during particularly strong events under appropriate conditions. Although enhancements in the median bioaerosol fraction do occur in winter, they also occur at other times of the year, likely due to the enhanced Aeolian activity driving dust events at this time from different sources. We hypothesise that this indicates the relative contribution of bioaerosol material in dust transported across the tropical Atlantic throughout the year is relatively uniform, comprised mainly of mixtures of dust and bacteria and/or bacterial fragments. We argue that this hypothesis is supported from analysis of measurements also at Cabo Verde just prior to the long-term monitoring experiment where UV-LIF single particle measurements were compared with laser ablation aerosol particle time-of-flight mass spectrometer (LAAP-ToF) measurements. These clearly show a very high correlation between particles with mixed biosilicate mass spectral signatures and UV-LIF biofluorescent signatures suggesting the bioaerosol concentrations are dominated by these mixtures. These observations should assist with constraining bioaerosol concentrations for tropical global climate model (GCM) simulations. Note that here we use the term “bioaerosol” to include mixtures of dust and bacterial material.

Nonnegligible emission of bioaerosols usually occurs during aeration of wastewater in aerator tanks in wastewater treatment plants (WWTPs). Literature had shown that the respiratory and intestinal diseases of workers at WWTPs are related to bioaerosols. Thus, quantitative microbial risk assessment (QMRA) based on Monte Carlo simulation was utilized in this research to assess the health risks of Gram-negative bacteria bioaerosol (GNBB) and Staphylococcus aureus bioaerosol (SAB) among academic visitors and staffs. Results showed that the concentrations of GNBB and SAB in the inverted umbrella aeration mode were consistently higher than those in the microporous aeration mode under all six size distribution ranges of the Anderson six-stage impactor. Thus, GNBB and SAB can be highly threatening to the weasand and first bronchus (or alveoli and third bronchus) for the exposure populations. The health risks (annual probability of infection (Py) and disease burden (DB)) of males were constantly higher than those of females for each certain exposure scenario. The health risks of staffs were higher than those of academic visitors when assessed by Monte Carlo simulation. The wearing of mask is an effective measure to minimize health risks through reducing the bioaerosol concentration intake. Especially, for the academic visitors and staffs exposed to GNBB, all their DB failed to meet the World Health Organization DB benchmark under various credible intervals when they were without a mask on. In a word, the results of health risk assessment in this research can be utilized as an educational tool and policy basis to facilitate the implementation of efficacious prevention measures to protect the public health from bioaerosol health threats in WWTPs.

RationaleInterrupting tuberculosis (TB) transmission requires an improved understanding of how – and when – the causative organism, Mycobacterium tuberculosis (Mtb), is aerosolized. Although Cough is commonly assumed to be the dominant source of Mtb aerosols, recent evidence of Cough-independent Mtb release implies the contribution of alternative mechanisms.ObjectiveTo compare the aerosolization of Mtb and particulate matter from GeneXpert-positive patients during three separate respiratory manoeuvres: Tidal Breathing (TiBr), Forced Vital Capacity (FVC), and Cough.MethodologyBioaerosol sampling and Mtb detection were combined with real-time assessments of CO2 production and particle counts from 39 confirmed TB patients.Measurements and Main ResultsTiBr and FVC produced comparable numbers of particles, with Cough producing >4-fold more. For all manoeuvres, the proportions of particles detected across size categories from 0.5 – 5 μm were similar, with minor differences observed only in particles between 1.5 – 2 μm (p = 0.014) and >5 μm (p = 0.020). Viable Mtb bacilli were detected in 66%, 70%, and 65% of TiBr, FVC, and Cough samples, respectively. Notably, while Cough produced 3-fold more Mtb than TiBr, the relative infrequency of coughing compared to breathing implies that TiBr likely contributes >90% of the daily aerosolised Mtb across a range of Cough frequencies.ConclusionsOur results suggest that, while Cough increases particle aerosolization compared to TiBr, this is not associated with increased Mtb aerosolization. Instead, TiBr produces more Mtb per particle than Cough. Assuming the number of viable Mtb organisms detected provides a proxy measure of patient infectiousness, these observations imply a significant contribution of TiBr to TB transmission.

Rationale: Patients with severe coronavirus disease (COVID-19) require supplemental oxygen and ventilatory support. It is unclear whether some respiratory support devices may increase the dispersion of infectious bioaerosols and thereby place healthcare workers at increased risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Objectives: To quantitatively compare viral dispersion from invasive and noninvasive respiratory support modalities. Methods: This study used a simulated ICU room with a breathing-patient simulator exhaling nebulized bacteriophages from the lower respiratory tract with various respiratory support modalities: invasive ventilation (through an endotracheal tube with an inflated cuff connected to a mechanical ventilator), helmet ventilation with a positive end-expiratory pressure (PEEP) valve, noninvasive bilevel positive-pressure ventilation, nonrebreather face masks, high-flow nasal oxygen (HFNO), and nasal prongs. Measurements and Main Results: Invasive ventilation and helmet ventilation with a PEEP valve were associated with the lowest bacteriophage concentrations in the air, and HFNO and nasal prongs were associated with the highest concentrations. At the intubating position, bacteriophage concentrations associated with HFNO (2.66 × 104 plaque-forming units [PFU]/L of air sampled), nasal prongs (1.60 × 104 PFU/L of air sampled), nonrebreather face masks (7.87 × 102 PFU/L of air sampled), and bilevel positive airway pressure (1.91 × 102 PFU/L of air sampled) were significantly higher than those associated with invasive ventilation (P

Bioaerosol concentrations in residential buildings located in the Northeastern US have not been widely studied. Here, in 2011-2015, we studied the presence and seasonal variability of culturable fungi and bacteria in three multi-family apartment buildings and correlated the bioaerosol concentrations with building ventilation system types and environmental parameters. A total of 409 indoor and 86 outdoor samples were taken. Eighty-five percent of investigated apartments had indoor-outdoor (I/O) ratios of culturable fungi below 1, suggesting minimal indoor sources of fungi. In contrast, 56% of the apartments had I/O ratios for culturable bacteria above 1, indicating the prominence of indoor sources of bacteria. Culturable fungi I/O ratios in apartments serviced by central heating, ventilation, and air-conditioning (HVAC) system were lower than those in apartments with window AC. The type of ventilation system did not have a significant effect on the presence of indoor culturable bacteria. A significant positive association was determined between indoor dew point (DP) levels and indoor culturable fungi (P

The investigation of bioaerosols in the recent years has become more important both indoors and outdoors. Due to expanding of livestock farm capacity, raising attention is paid to this source of emissions. The objective of the present study was to estimate the distribution of bioaerosols in the animal husbandry and its surroundings. Over 2 fattening periods with different animal ages and weights, the main emphasis was put on the total concentrations of mesophilic bacteria andStaphylococcusspp., especially the speciesS. aureus. The bioaerosols were sucked in with an AGI-30 Impinger, and nasal and neck skinfold swab samples were collected supplementary from randomly selected pigs. From the first series of measurements, the total concentration of mesophilic bacteria was 6.2 × 105 cfu/m3and dropped to 2.6 × 105 cfu/m3with increasing growth of the swine. The concentration ofStaphylococcusspp. was 8.8 × 104 cfu/m3and decreased to 9.4 × 103 cfu/m3by the end. In the empty barn, the total concentration of mesophilic bacteria was 9.1 × 104 cfu/m3and forStaphylococcusspp., 1.1 × 104 cfu/m3. At the beginning of the second series of measurements, the total concentration of mesophilic bacteria was 6.6 × 104 cfu/m3and dropped to 4.4 × 104 cfu/m3with the increasing growth of the piglets. The concentrations ofStaphylococcusspp. fluctuated along the second measurement series. The speciesStaphylococcus aureuswas detected in nasal swabs of selected swine including MRSA. Temperature and humidity had no influence on the concentrations of mesophilic bacteria in the swine barn.

Resumen La práctica odontológica se enfrenta al cambio de paradigmas y modificación de protocolos en bioseguridad, aspecto este que se ha convertido en una variable a ser practicada por cada profesional como parte de su conducta en todo momento para poder sobrevivir como profesión ante la pandemia mundial que representa el riesgo de transmisión del nuevo coronavirus llamado COVID-19. Uno de los problemas de mayor importancia en bioseguridad dental lo representa la generación de bioaerosoles, debido a que son vectores que transportan microorganismos del exterior hacia dentro del organismo de las personas, lo cual genera un potencial riesgo ocupacional ya conocido en las ciencias odontológicas pero que se potencia con la transmisibilidad y patogenicidad del nuevo coronavirus. Hasta el momento se tienen muchas interrogantes sobre la transmisión a través de aerosoles del SARS-CoV-2 , por lo que el objetivo general de abordaje de esta revisión se centra en comprender los elementos científicos que rigen la aerodinámica de los bioaerosoles aplicados al entorno dental y como éstos pueden convertirse en un potencial diseminador del virus presente en la saliva al momento de realizar procedimientos odontológicos intraorales en pacientes infectados. La comprensión de la aerodinámica de los bioaerosoles nos ayuda a entender como el SARS-CoV-2 presente en el bioaerosol generado por procedimientos odontológicos en pacientes infectados puede variar en términos de viabilidad e infectabilidad al influir otros factores como lo son humedad relativa, temperatura, corrientes de aire, factores fisicoquímicos del bioaerosol y el sistema inmune del huésped. Abstract Dental practice faces the paradigm shift and the modification of protocols in biosafety, an aspect that has become a variable to be practiced by each professional as part of their conduct at all times in order to survive as a profession in the face of the global pandemic that it represents the risk of transmission of the new coronavirus called COVID-19. One of the most important problems in dental biosecurity is represented by the generation of bioaerosols, since these are vectors that transport microorganisms to inside people’s bodies, which generates a potential occupational risk already known in the dental sciences but that it is enhanced with the transmissibility and pathogenicity of the new coronavirus. Until now, there are many questions about transmission through aerosols of SARS-CoV-2 , so the general objective of this review is to understand the scientific elements that govern the aerodynamics of bioaerosols applied to the dental environment and how these can become a potential virus disseminator when intraoral dental procedures are performed in infected patients. Understanding the aerodynamics of bioaerosols helps us understand how SARS-CoV-2 present in bioaerosol generated by dental procedures in infected patients can vary in terms of viability and infectivity by influencing other factors such as relative humidity, room temperature, air currents, bioaerosol physicochemical factors and the host´s immune system

Background Staphylococci species are the major constituents of infectious bioaerosols, particularly methicillin-resistant Staphylococci (MRS) have serious health impacts. Here, the bacterial burden was quantified, especially prevalence of MRS in bioaerosols collected from indoors of Dr. B.R. Ambedkar Central Library (DBRACL) and Central Laboratory Animal Resources (CLAR) of Jawaharlal Nehru University, New Delhi, India. Air samplings from DBRACL and CLAR were done using the settle plate method and SKC biosampler, respectively. Results This study showed a maximum 6757 CFU/m2/hr of bacterial load in the DBRACL reading room, while unacceptable bacterial loads (> 1000 CFU/m3 of air) at different sites of CLAR. Further, at both the sampling sites the predominance of coagulase negative Staphylococci (CNS) was observed. A total 22 and 35 Staphylococci isolates were isolated from DBRACL and CLAR bioaerosols, respectively. Majority (16/22) of the Staphylococcal isolates from DBRACL belonged to human-associated Staphylococci where S. haemolyticus (5/22) was the most dominating species. However, in CLAR facility centre, animal-associated Staphylococci (19/35) were dominating, where S. xylosus (12/35) was the most dominating species. Further, antibiotic sensitivity tests revealed 41% MRS and 73% multidrug resistant (MDR) among airborne Staphylococci from DBRACL indoor bioaerosols. Similarly, in CLAR facility, approximately, 66% Staphylococci isolates were methicillin resistant, out of which 2 isolates showed high MIC value ≥ 16 μg/mL. Further, we confirmed the presence of 49% multidrug resistant Staphylococci in the indoor air of CLAR facility. Conclusions This study suggested that the exposure of workers and students in CLAR to such a high concentration of drug-resistant Staphylococci should not be undermined, as these bacterial concentrations are the direct representative of inhalable particulate matter (PM2.5) as per collection procedure. Simultaneously, passive sampling from DBRACL assessed the risks due to microbial contamination in particle agglomerates, which may deposit on the crucial surfaces such as wounds/ cuts or on the frequently used items.

In this study, atmospheric bioaerosol particles were collected from March to December 2015 in the coastal region of Qingdao. The dominant fungi were identified, and the concentrations and size distributions of bacteria, total fungi and dominant fungi were measured. The most dominant fungal taxon was Cladosporium, followed by Alternaria, Penicillium and Aspergillus. The concentrations of fungi showed significant seasonal variation (p 7.0 μm. The size patterns of the four dominant fungi were distinct due to their respective properties. With correlation analysis, we found PM10, CO and NO2 were positively associated with the bacterial concentration. The factors correlated with fungal concentrations included temperature, relative humidity, CO, NO2, SO2 and O3. The results of RDA showed that the most important meteorological factors affecting the microorganism species composition were temperature and relative humidity, and the dominant air pollutants were SO2, CO and O3. We selected related parameters to conduct multiple linear regression analysis to explore the synergistic effects on a given microorganism. The contribution to the rate of changes in bacterial and fungal concentrations caused by related factors was less than 30%, indicating that the sources and community changes had a great influence on bioaerosol concentrations. The more detailed the classification of microorganisms is, the more specific correlation information may be obtained through our analysis method.

Globally, norovirus is the most common gastroenteritis causing pathogen. Annually, norovirus causes 685 million cases of acute gastroenteritis and 200,000 deaths, worldwide. Recent evidence has suggested that norovirus can also be spread via aerosolization; however, an indoor generation source has yet to be determined. We optimized a sampling method for the collection of aerosolized norovirus using murine norovirus (MNV) as a surrogate. Optimization of the sampling method was performed using two bioaerosol samplers (SKC BioSampler and the NIOSH Bioaerosol Cyclone Sampler 251) and two sampling media (Hanks Balanced Salt Solution [HBSS] and Phosphate Buffered Saline [PBS]). Murine norovirus was aerosolized in a bioaerosol chamber and later collected using each sampler/media combination. Collected MNV was quantified using quantitative polymerase chain reaction (qPCR). Intact capsids of MNV were assessed using propidium monoazide dye in combination with qPCR and confirmed with transmission electron microscopy. Ten trials were conducted, with each trial lasting for 30 min. The SKC BioSampler collected a significantly higher concentration of MNV than the NIOSH-251 sampler did (p-value

Objective This research aims to determine the correlation of bioaerosol pollution with temperature, humidity, and lighting in the ICU for measurement in morning and midday. Methods The research was an observational analytic with a cross-sectional study design conducted in Dr. Wahidin Sudirohusodo hospital. The sample of the research consisted of 8 ICU rooms. The data were analyzed using the Spearman test. Results The total of bioaerosol in the morning ranged from 320–1885 CFU/m3 and the total of bioaerosol in midday ranged from 366–1895 CFU/m3. The result showed that the humidity factor correlated with the total of microbial (p = 0.006) but the temperature (p = 0.471) and lighting (p = 0.232) did not correlate with the total of bioaerosol for morning measurement. While the temperature, humidity and lighting factors correlated with the total of bioaerosol (p = 0.000) for midday measurement. Conclusion The quality of bioaerosol correlates with temperature, humidity, and lighting. For further improvement designing well-built HVAC.

Background The aim of the study was to assess the occupational exposure to Staphylococcus aureus bacteria, including methicillin- resistant S. aureus (MRSA) and other antibiotic-resistant strains in the municipal wastewater treatment plants (WWTPs) environment. Material and methods In 16 WWTPs in Poland, 33 wastewater and 253 air samples were collected in the spring-summer season. The microbiological analysis was carried out using a chromogenic medium. Species identification was carried out using the matrix assisted laser desorption ionization time-of-flight method, while the antibiotic-resistance analysis was performed with an automatic method. Results Among 2805 bacterial isolates from the air and wastewater, 574 were identified as S. aureus species (20.5%). The presence of S. aureus species was found in 11 WWTPs (69%), among them in 11 WWTPs in raw wastewater and in 1 WWTP additionally in treated wastewater. The concentrations of S. aureus in wastewater ranged 2-1215 colony-forming units per milliliter (CFU/ml). In the air, 2 S. aureus isolates were identified in concentrations of 5 and 10 CFU/m3; both samples were collected at the stage of mechanical wastewater treatment. The results revealed the following trend: the higher the outdoor temperature, the bigger the number of WWTPs with confirmed S. aureus presence. Among 149 S. aureus isolates (2 from the air and 147 from wastewater, including 2 MRSA), 100 isolates were resistant only to penicillin, while 34 isolates showed multi-antibiotic resistance (to penicillin and other drugs). It was found that isolated bacteria were resistant almost strictly to critical and highly important antibiotics in veterinary medicine. Conclusions In general, WWTPs workers are occupationally exposed to S. aureus, including MRSA, and other antibiotic- and multi-antibiotic-resistant strains. The highest risk of infection concerns the activities carried out in direct contact with wastewater or devices through which wastewater flows, particularly at the stage of mechanical treatment. A significant source of S. aureus seems to be intensive livestock farming located in the area of the WWTPs under analysis. The study confirms the necessity to disinfect the wastewater discharging into WWTPs. Med Pr. 2020;71(3):265-78.