Seasonal and spatial variations in concentration, diversity, and antibiotic resistance of ambient bioaerosols in an arid region.

The airborne microbiome significantly influences human health and atmospheric processes within Earth's troposphere and is a crucial focus for scientific research. This study aimed to analyze the composition, diversity, distribution, and spatiotemporal characteristics of airborne microbes in Qatar's ambient air. Air samples were collected using a sampler from ten geographically or functionally distinct locations during a period of one year. Spatial and seasonal variations significantly impacted microbial concentrations, with the highest average concentrations observed at 514 ± 77 CFU/m3 for bacteria over the dry-hot summer season and 134 ± 31 CFU/m3 for fungi over the mild winter season. Bacterial concentrations were notably high in 80% of the locations during the dry-hot summer sampling period, while fungal concentrations peaked in 70% of the locations during winter. The microbial diversity analysis revealed several health-significant bacteria including the genera Chryseobacterium, Pseudomonas, Pantoea, Proteus, Myroides, Yersinia, Pasteurella, Ochrobactrum, Vibrio, and fungal strains relating to the genera Aspergillus, Rhizopus Fusarium, and Penicillium. Detailed biochemical and microscopic analyses were employed to identify culturable species. The strongest antibiotic resistance (ABR) was observed during the humid-hot summer season, with widespread resistance to Metronidazole. Health risk assessments based on these findings indicated potential risks associated with exposure to high concentrations of specific bioaerosols. This study provides essential baseline data on the natural background concentrations of bioaerosols in Qatar, offering insights for air quality assessments and forming a basis for public health policy recommendations, particularly in arid regions.

Enriched Aerosol-to-Hydrosol Transfer for Rapid and Continuous Monitoring of Bioaerosols.

Bioaerosols, including infectious diseases such as COVID-19, are a continuous threat to global public safety. Despite their importance, the development of a practical, real-time means of monitoring bioaerosols has remained elusive. Here, we present a novel, simple, and highly efficient means of obtaining enriched bioaerosol samples. Aerosols are collected into a thin and stable liquid film by the unique interaction of a superhydrophilic surface and a continuous two-phase centrifugal flow. We demonstrate that this method can provide a concentration enhancement ratio of ∼2.4 × 106 with a collection efficiency of ∼99.9% and an aerosol-into-liquid transfer rate of ∼95.9% at 500 nm particle size (smaller than a single bacterium). This transfer is effective in both laboratory and external ambient environments. The system has a low limit of detection of <50 CFU/m3air using a straightforward bioluminescence-based technique and shows significant potential for air monitoring in occupational and public-health applications.

What is the relationship between indoor air quality parameters and airborne microorganisms in hospital environments? A systematic review and meta-analysis.

Airborne microorganisms in hospitals have been associated with several hospital-acquired infections (HAIs), and various measures of indoor air quality (IAQ) parameters such as temperature, relative humidity, carbon dioxide (CO2 ), particle mass concentration, and particle size have been linked to pathogen survival or mitigation of pathogen spread. To investigate whether there are quantitative relationships between the concentration of airborne microorganisms and the IAQ in the hospital environment. Web of Science, Scopus and PubMed databases were searched for studies reporting airborne microbial levels and any IAQ parameter(s) in hospital environments, from database inception to October 2020. Pooled effect estimates were determined via random-effects models. Seventeen of 654 studies were eligible for the meta-analysis. The concentration of airborne microbial measured as aerobic colony count (ACC) was significantly correlated with temperature (r = 0.25 [95% CI = 0.06-0.42], p = 0.01), CO2 concentration (r = 0.53 [95% CI = 0.40-0.64], p Ë‚ 0.001), particle mass concentration (≤5 µg/m3 ; r = 0.40 [95% CI = 0.04-0.66], p = 0.03), and particle size (≤5 and ˃5 µm), (r = 0.51 [95% CI = 0.12-0.77], p = 0.01 and r = 0.55 [95% CI = 0.20-0.78], p = 0.003), respectively, while not being significantly correlated with relative humidity or particulate matter of size >5 µm. Conversely, airborne total fungi (TF) were not significantly correlated with temperature, relative humidity, or CO2 level. However, there was a significant weak correlation between ACC and TF (r = 0.31 [95% CI = 0.07-0.52], p = 0.013). Although significant correlations exist between ACC and IAQ parameters, the relationship is not definitive; the IAQ parameters may affect the microorganisms but are not responsible for the presence of airborne microorganisms. Environmental parameters could be related to the generating source, survival, dispersion, and deposition rate of microorganisms. Future studies should record IAQ parameters and factors such as healthcare worker presence and the activities carried out such as cleaning, sanitizing, and disinfection protocols. Foot traffic would influence both the generation of microorganisms and their deposition rate onto surfaces in the hospital environment. These data would inform models to improve the understanding of the likely concentration of airborne microorganisms and provide an alternative approach for real-time monitoring of the healthcare environment.

Evaluation of survival rates of airborne microorganisms on the filter layers of commercial face masks.

After the WHO designated COVID-19 a global pandemic, face masks have become a precious commodity worldwide. However, uncertainty remains around several details regarding face masks, including the potential for transmission of bioaerosols depending on the type of mask and secondary spread by face masks. Thus, understanding the interplay between face mask structure and harmful bioaerosols is essential for protecting public health. Here, we evaluated the microbial survival rate at each layer of commercial of filtering facepiece respirators (FFRs) and surgical masks (SMs) using bacterial bioaerosols. The penetration efficiency of bacterial particles for FFRs was lower than that for SMs; however, the microbial survival rate for all tested masks was >13%, regardless of filtration performance. Most bacterial particles survived in the filter layer (44%-77%) (e.g., the core filtering layer); the outer layer also exhibited significant survival rates (18%-29%). Most notably, survival rates were determined for the inner layers (<1% for FFRs, 3%-16% for SMs), which are in contact with the respiratory tract. Our comparisons of the permeability and survival rate of bioaerosols in each layer will contribute to bioaerosol-face mask research, while also providing information to facilitate the establishment of a mask-reuse protocol.

Airborne particles and microorganisms in a dental clinic: Variability of indoor concentrations, impact of dental procedures, and personal exposure during everyday practice.

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.

Swine-Origin H1 Influenza Viruses Isolated from Humans Exhibit Sustained Infectivity in an Aerosol State.

The relative importance of influenza virus transmission via aerosols is not fully understood, but experimental data suggest that aerosol transmission may represent a critical mode of influenza virus spread among humans. Decades ago, prototypical laboratory strains of influenza were shown to persist in aerosols; however, there is a paucity of data available covering currently circulating influenza viruses, which differ significantly from their predecessors. In this study, we evaluated the longevity of influenza viruses in aerosols generated in the laboratory. We selected a panel of H1 viruses that exhibit diverse transmission profiles in the ferret model, including four human isolates of swine origin (referred to as variant) and a seasonal strain. By measuring the ratio of viral RNA to infectious virus maintained in aerosols over time, we show that influenza viruses known to transmit efficiently through the air display enhanced stability in an aerosol state for prolonged periods compared to those viruses that do not transmit as efficiently. We then assessed whether H1 influenza virus was still capable of infecting and causing disease in ferrets after being aged in suspended aerosols. Ferrets exposed to very low levels of influenza virus (≤17 PFU) in aerosols aged for 15 or 30 min became infected, with five of six ferrets shedding virus in nasal washes at titers on par with ferrets who inhaled higher doses of unaged influenza virus. We describe here an underreported characteristic of influenza viruses, stability in aerosols, and make a direct connection to the role this characteristic plays in influenza transmission.IMPORTANCE Each time a swine influenza virus transmits to a human, it provides an opportunity for the virus to acquire adaptations needed for sustained human-to-human transmission. Here, we use aerobiology techniques to test the stability of swine-origin H1 subtype viruses in aerosols and evaluate their infectivity in ferrets. Our results show that highly transmissible influenza viruses display enhanced stability in an aerosol state compared to viruses that do not transmit as efficiently. Similar to human-adapted strains, swine-origin influenza viruses are infectious in ferrets at low doses even after prolonged suspension in the air. These data underscore the risk of airborne swine-origin influenza viruses and support the need for continued surveillance and refinement of innovative laboratory methods to investigate mammalian exposure to inhaled pathogens. Determination of the molecular markers that affect the longevity of airborne influenza viruses will improve our ability to quickly identify emerging strains that present the greatest threat to public health.

The influence of air-dispersed essential oils from lemon (Citrus limon) and silver fir (Abies alba) on airborne bacteria and fungi in hospital rooms.

Airborne bacteria and fungi are an ongoing problem in hospitals. Because of the antimicrobial activities of essential oils (EOs) dispersion of EOs into the air may help to reduce this contamination. The aim of this study was to evaluate the efficacy of the dispersion of selected EOs in reducing the microbial contamination in two hospital wards. The study was carried out at two wards of a 1,227-bed acute-care hospital in Austria. The concentration of airborne bacteria and fungi was measured in patient rooms before and after dispersion of a mixture of Citrus limon EO and Abies alba EO. Before dispersion of the EOs in both wards the mean concentration of bacteria was in a typical range (123 colony forming units (CFU) m-3 and 104 CFU m-3) while the mean concentration of fungi differed substantially (155 CFU m-3 and 28 CFU m-3). After dispersion of the EOs, a reduction in both bacterial and fungal contamination was observed. In the first two hours the mean concentration of airborne bacteria and fungi was reduced by approximately 40% and 30%-60% respectively. The selected EO mixture is effective in reducing the microbial contamination of the indoor air.

Assessment of microbiological aerosol concentration in selected healthcare facilities in southern Poland.

OBJECTIVES: This study was aimed to assess the concentration of microbial aerosol and species composition of airborne staphylococci in 10 healthcare facilities in southern Poland including primary healthcare units and hospital wards; and to assess whether the selected components of microbial aerosol pose a threat of severe infections to either patients or the personnel. METHODS: The study was conducted at monthly intervals over a period of one year. Air samples were collected by MAS-100 sampler. The number of mesophilic bacteria, mould fungi, actinomycetes and staphylococci was determined on general and selective media. The species identification of staphylococci was conducted using API tests for strains that were pre-selected based on macroscopic and microscopic observations. RESULTS: A total number of 1,584 samples were collected during the sampling period. The numbers of airborne microorganisms varied between the examined premises and between the seasons of the year. The observed differences were statistically significant with one exception for actinomycetes and their differences between the examined premises. The concentrations of mesophilic bacteria varied from 5 to 297 CFU/m3 of air, for Staphylococcus the values ranged from 1 to 96 CFU/m3, for fungi - from 1 to 100 CFU/m3, and the number of actinomycetes ranged from 7 to 321 CFU/m3. Ten species of coagulase-negative staphylococci (CoNS) were identified among 55 isolates with S. saprophyticus and S. warneri being the most frequently detected (n = 14 and 13, respectively). S. haemolyticus, which is one of the most common causal agents of nosocomial infections was observed in four facilities (n = 5). CONCLUSIONS: The microbial concentrations varied both between the seasons of the year and between the examined facilities. The highest bioaerosol concentrations were observed in most crowded premises. The identified species of staphylococci, although not typically associated with human infections, are common causal agents of nosocomial infections and infections in immunocompromised people.

Microorganism-ionizing respirator with reduced breathing resistance suitable for removing airborne bacteria.

In this paper, we have demonstrated the feasibility of using microorganism-ionizing respirators with reduced breathing resistance to remove airborne bacteria. Using a miniaturized corona ionizer and two pairs of separator electrodes, airborne bacteria were ionized and removed from the airflow. Two microorganism-ionizing respirator designs were experimentally evaluated with flow rates ranging from ∼10 to 20 L/min and yielded airborne bacterial removal efficiencies of ∼75%-100%. Further, they were in close agreement with the analytical airborne particle removal efficiencies, at a similar range of flow rates. These flow rates also correspond to the breathing rates of standing and walking adults. More importantly, the breathing resistance could be reduced by more than 50% for flow rates of ∼200 L/min. Using manganese (IV) oxide coated mesh, the ozone concentration in the air outflow was reduced to less than 0.1 ppm, at a flow rate of ∼20 L/min, thus enabling safe use. The power consumption was less than 1 W.

Assessment of workers' exposure to bioaerosols in a French cheese factory.

Hundreds of different cheeses are produced in France, where 23.9kg of cheese were consumed per inhabitant in 2009, when it was ranked the second cheese-consuming nation. To meet this considerable demand, a large number of cheese factories exist where many workers, especially cheese washers, may be exposed to fungal bioaerosols that can lead to adverse toxinic and allergic effects. Airborne bacteria, fragments, or microbial by-products (endotoxins) are also found and contribute to total worker exposure. However, there is almost no published data concerning worker exposure or characteristics of bioaerosols emitted during these activities. Here, we measured the parameters (concentrations, species present, and size distribution) of the culturable fungal bioaerosol emitted in a French natural-rind cheese-maturing cellar. Concentrations of airborne bacteria and endotoxins were also measured. The main tasks were investigated using stationary or personal sampling over three consecutive days. Depending on the work area, high concentrations of culturable mesophilic microorganisms were measured (using closed-face cassettes): from 10(4) to 2×10(8) CFU m(-3) for fungi and from 10(3) to 10(6) CFU m(-3) for bacteria. These concentrations are 10- to 100000-fold higher than those measured at two reference points (indoor and outdoor) that are assumed not to be contaminated by the plant's activities. Endotoxin concentrations were between 10 and 300 EU m(-3) in the plant. Exposure was further assessed by identifying the predominant culturable fungi (allergenic Mucor fuscus and Penicillium sp.) and by measuring particle size distributions (cascade impactor). Airborne fungal entities (spores, mycelium strands and fragments, agglomerates, etc.) were found with aerodynamic diameters from 3 to over 20 µm. A metrological approach was used to fully characterize the culturable fungal aerosols generated during cheese maturing in this plant. The results show that workers are exposed to concentrations of airborne culturable fungi, sometimes very high, throughout the manufacturing process. In addition to fungi, culturable bacteria and endotoxins are also present in the work atmosphere. All these microbial organisms thus contribute in a complex manner to total worker exposure. Despite the lack of both occupational exposure limit values and standardized measuring methods, our results suggest that an immunological risk may occur among workers, especially for cheese brushers, cheese washers, and packagers who are the most exposed workers in the factory.

An airborne actinobacteria Nocardiopsis alba isolated from bioaerosol of a mushroom compost facility.

Actinobacteria are widely distributed in many environments and represent the most important trigger to the occupant respiratory health. Health complaints, including hypersensitivity pneumonitis of the workers, were recorded in a mushroom compost facility (MCF). The studies on the airborne bacteria were carried out to find a possible microbiological source of these symptoms. Culture analysis of compost bioaerosols collected in different location of the MCF was performed. An assessment of the indoor microbial exposure revealed bacterial flora of bioaerosol in the mushroom compost facility represented by Bacillus, Geobacillus, Micrococcus, Pseudomonas, Staphylococcus spp., and actinobacterial strain with white aerial mycelium. The thermotolerant actinobacterial strain of the same morphology was repeatedly isolated from many locations in MCF: air, compost sample, and solid surface in production hall. On the base of complex morphological, chemotaxonomic, and phylogenetic characteristics, the isolate has been classified as Nocardiopsis alba. Dominant position of N. alba in microbial environment of the mushroom compost facility may represent an indicator microorganism in compost bioaerosol. The bioavailability of N. alba in mushroom compost facility creates potential risk for the health of workers, and the protection of respiratory tract and/or skin is strongly recommended.

Towards tailored guidelines for microbial air quality in the food industry.

Airborne microorganisms in food processing environments pose a potential risk for food product contamination. Yet, the absence of established standards or guidelines setting quantitative limits on airborne microorganisms underscores a critical gap in current regulatory frameworks. This review seeks to explore the feasibility of establishing quantitative limits for airborne microorganisms in food processing facilities, aiming to provide evidence-based guidance to enhance food safety practices in the industry. The review begins by addressing the complexities of microbial air quality in the food industry through a general literature search covering sources of airborne microorganisms, factors affecting particle deposition, air sampling methods and preventive measures. Subsequently, it employs a structured approach to assess the significance of air quality and its impact on product quality. Utilizing the PRISMA method, relevant scientific literature from May 2002 to May 2022 was examined, resulting in 26 articles meeting inclusion criteria from a pool of 11,737 original research papers. Additionally, the review investigates existing probability models for assessing airborne contamination to enhance air quality risk assessment in food safety management systems. The literature reveals a lack of substantial evidence supporting a direct correlation between airborne microorganisms and food contamination. The absence of standardized air sampling methodologies in previous studies hinders the comparability and reliability of research findings. Additionally, the literature fails to establish a conclusive relationship between influencing factors such as total particle counts, temperature, relative humidity and airborne contamination. Contradictory probability models for quantifying airborne contamination, and the absence of tailored preventive measures, hinder effective control and undermine microbial contamination control in diverse food processing contexts. In conclusion, the development of numeric guidelines for airborne contamination necessitates a tailored approach, considering factors such as product characteristics and production context. By integrating risk assessment models into this process, a more thorough comprehension of contamination risks can be achieved, providing tailored guidance based on the identified risk levels for each product. Ongoing collaborative efforts are essential to develop evidence-based guidelines that effectively mitigate risks without incurring unnecessary costs.

VLP-based model for the study of airborne viral pathogens.

The recent COVID-19 pandemic has underscored the danger of airborne viral pathogens. The lack of model systems to study airborne pathogens limits the understanding of airborne pathogen distribution as well as potential surveillance and mitigation strategies. In this work, we develop a novel model system to study airborne pathogens using virus-like particles (VLPs). Specifically, we demonstrate the ability to aerosolize VLP and detect and quantify aerosolized VLP RNA by reverse transcription-loop-mediated isothermal amplification in real-time fluorescent and colorimetric assays. Importantly, the VLP model presents many advantages for the study of airborne viral pathogens: (i) similarity in size and surface components; (ii) ease of generation and noninfectious nature enabling the study of biosafety level 3 and biosafety level 4 viruses; (iii) facile characterization of aerosolization parameters; (iv) ability to adapt the system to other viral envelope proteins, including those of newly discovered pathogens and mutant variants; and (v) the ability to introduce viral sequences to develop nucleic acid amplification assays. IMPORTANCE: The study and detection of airborne pathogens are hampered by the lack of appropriate model systems. In this work, we demonstrate that noninfectious virus-like particles (VLPs) represent attractive models to study airborne viral pathogens. Specifically, VLPs are readily prepared, are similar in size and composition to infectious viruses, and are amenable to highly sensitive nucleic acid amplification techniques.

Recent progress in online detection methods of bioaerosols.

The aerosol transmission of coronavirus disease in 2019, along with the spread of other respiratory diseases, caused significant loss of life and property; it impressed upon us the importance of real-time bioaerosol detection. The complexity, diversity, and large spatiotemporal variability of bioaerosols and their external/internal mixing with abiotic components pose challenges for effective online bioaerosol monitoring. Traditional methods focus on directly capturing bioaerosols before subsequent time-consuming laboratory analysis such as culture-based methods, preventing the high-resolution time-based characteristics necessary for an online approach. Through a comprehensive literature assessment, this review highlights and discusses the most commonly used real-time bioaerosol monitoring techniques and the associated commercially available monitors. Methods applied in online bioaerosol monitoring, including adenosine triphosphate bioluminescence, laser/light-induced fluorescence spectroscopy, Raman spectroscopy, and bioaerosol mass spectrometry are summarized. The working principles, characteristics, sensitivities, and efficiencies of these real-time detection methods are compared to understand their responses to known particle types and to contrast their differences. Approaches developed to analyze the substantial data sets obtained by these instruments and to overcome the limitations of current real-time bioaerosol monitoring technologies are also introduced. Finally, an outlook is proposed for future instrumentation indicating a need for highly revolutionized bioaerosol detection technologies.

Variations, seasonal shifts and ambient conditions affecting airborne microorganisms and particles at a southeastern Mediterranean site.

Airborne particles are known climate drivers whilst the impact of microorganisms is investigated with increasing interest. The particle number size distribution (0.012-10 µm), PM10 concentrations, bacterial communities and cultivable microorganisms (bacteria and fungi) were measured simultaneously throughout a yearly campaign at a suburban location at the city of Chania (Greece). Most of the bacteria identified belonged to Proteobacteria, Actinobacteriota, Cyanobacteria, and Firmicutes, with Sphingomonas having a dominant partition at the genus level. Statistically lower concentrations of all microorganisms and bacterial species richness during the warm season due to the direct impact of temperature and solar radiation suggested notable seasonality. On the other hand, statistically significant higher concentrations of particles <0.1 µm during the cold season was attributed to indirect seasonality with enrichment due to heating emissions. Analysis of wind direction data demonstrated that a land prevailing origin of air resulted in statistically higher microorganism concentrations, bacterial species richness and diversity, indicating the continental environment as a dominant contributor in shaping airborne microbial load (compared to a marine air origin). Likewise, statistically higher concentration of particles <0.1 µm were measured during a land prevailing air origin as a direct result of nanoparticle enrichment from anthropogenic activities. Long-range transport of both particles and biological components was evidenced by the increased concentrations of cultivable microorganisms (with a distinct contribution at sizes >1 µm), supermicron particles and bacterial species richness during Sahara dust events. Factorial analysis of the impact of 7 environmental parameters on bacterial communities profile has identified temperature, solar radiation, wind origin and Sahara dust as strong contributors. Increased correlations between airborne microorganisms and coarser particles (0.5-10 µm) suggested resuspension, especially during stronger winds and moderate ambient humidity, whereas, increased relative humidity during stagnant conditions acted as inhibitor for suspension.

Oxidative Stress Contributes to Bacterial Airborne Loss of Viability.

While the airborne decay of bacterial viability has been observed for decades, an understanding of the mechanisms driving the decay has remained elusive. The airborne transport of bacteria is often a key step in their life cycle and as such, characterizing the mechanisms driving the airborne decay of bacteria is an essential step toward a more complete understanding of microbial ecology. Using the Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate (CELEBS), it was possible to systematically evaluate the impact of different physicochemical and environmental parameters on the survival of Escherichia coli in airborne droplets of Luria Bertani broth. Rather than osmotic stress driving the viability loss, as was initially considered, oxidative stress was found to play a key role. As the droplets evaporate and equilibrate with the surrounding environment, the surface-to-volume ratio increases, which in turn increased the formation of reactive oxygen species in the droplet. These reactive oxygen species appear to play a key role in driving the airborne loss of viability of E. coli. IMPORTANCE The airborne transport of bacteria has a wide range of impacts, from disease transmission to cloud formation. By understanding the factors that influence the airborne stability of bacteria, we can better understand these processes. However, while we have known for several decades that airborne bacteria undergo a gradual loss of viability, we have not previously identified the mechanisms driving this process. In this work, we discovered that oxygen surrounding an airborne droplet facilitates the formation of reactive oxygen species within the droplet, which then gradually damage and kill bacteria within the droplet. This discovery indicates that adaptations to help bacteria deal with oxidative stress may also aid their airborne survival and be essential adaptations for bacterial airborne pathogens. Understanding the adaptations bacteria need to survive in airborne droplets could eventually lead to the development of novel antimicrobials designed to inhibit their airborne survival, helping to prevent the transmission of disease.

Observational study of sterile field bioburden levels during orthopedic arthroplasty surgery in operating rooms complying with current United States ventilation specifications.

BACKGROUND: Airborne contamination from microbe carrying particles (MCPs) is a risk factor for devastating early onset periprosthetic joint infection(PJIs). There are no published guidelines to quantify this risk factor for PJI events. This observational cohort project addresses this gap and utilizes a simple passive system to produce quantitative data from 80 total joint replacement cases performed in operating rooms built to current USA standards. METHODS: A petri dish-based system inspired by industrial cleanroom technology was deployed. Surgical helmet systems (SHSs) and strict protocols were used in all cases. 450 MCPs/m2 was used as a cutoff for bioburden. This benchmark corresponds to the ultraclean air standard of 10 MCPs/m3. RESULTS: 75/80 cases (94%) achieved desired benchmark levels of bioburden at the wound zone compared to only 52/80 (65%) of back table zones. No surgical site infections (SSI) or PJI events (0/80; 95% CI, 0.00-3.68%) at minimum 18-month (average 25.8 months) follow-up were detected. DISCUSSION: The current USA ventilation design uses low velocity airflow and appears to achieve ultraclean air conditions at the surgical site but requires SHSs and strict protocols. Higher contamination levels seen in back tables are consistent with this design. CONCLUSIONS: This settle plate system may be useful for early onset PJI event investigations and thus lower the incidence of these complications.

Risk Influence of Some Environmental and Behavioral Factors on Air Contamination in the Operating Room: An Experimental Study.

Air contamination in operating rooms (ORs) depends on the conditions of the room and on activities therein performed. Methodologies of air quality assessment in ORs are often inadequately described in the scientific literature, and the time required for a change in status in air quality is never taken into account. The purpose of this study was to determine the influence of the state and the presence of human operators on air quality by implementing a precise measurement protocol that also took into account the time required for changes in the room to affect air pollution. As the main indicators of air pollution, bacterial load and concentration of airborne dust were measured. The results showed that: the use of surgical masks by operators in the OR did not significantly affect bacterial load within a distance of 2 m; keeping OR doors open did not induce a significant increase in bacterial load and of 5 µm particles while 10 µm particles concentration was positively affected; and air pollution measured with open doors was not significantly different from that due to the presence of two staff members, whether or not they were wearing masks. The results clarified the role of some factors on air pollution in ORs.

The effect of microorganisms (bacteria and fungi) in dust storm on human health.

Dust storms expose people suspended particles, microorganisms and potential allergens that have been absorbed by dust particles during airborne transport. The purpose of this study was investigation effect of microorganisms (bacteria and fungi) in dust storm on human health. Databases used to for searched were the PubMed, Google Scholar, Web of Science, Springer and Science Direct (Scopus). 58 papers based on abstract and article text filtered. In the end after sieve we selected 10 papers. Identify all relevant studies published 1978-2022. The literature showed that green spaces created by city officials in different areas include a set of trees and shrubs in accordance with the effect of microorganisms (bacteria and fungi) in dust storm on human health. Based on the result the many studies are conducted every year on the characteristics and different sources of dust, one of the most important of which is the ability of these storms to carry pathogenic microorganisms. the purpose of this study is the effect of bacteria and fungi in dust storms on human health. The findings of this study showed that the evaluation of various studies showed that with the occurrence of dust storms that originate from different sources, in addition to transporting suspended solids, pathogenic bacteria and fungi are also transmitted by dust storms from near and far places and cause various diseases of these include respiratory and pulmonary problems, upper respiratory tract infections, and cardiovascular disease.