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Concept: Bioaerosol

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The potential risks associated with “toilet plume” aerosols produced by flush toilets is a subject of continuing study. This review examines the evidence regarding toilet plume bioaerosol generation and infectious disease transmission.

Concepts: Epidemiology, Infectious disease, Infection, Aerosol, Toilet, Toilets in Japan, Flush toilet, Bioaerosol

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BACKGROUND: Most surgical masks are not certified for use as respiratory protective devices (RPDs). In the event of an influenza pandemic, logistical and practical implications such as storage and fit testing will restrict the use of RPDs to certain high-risk procedures that are likely to generate large amounts of infectious bioaerosols. Studies have shown that in such circumstances increased numbers of surgical masks are worn, but the protection afforded to the wearer by a surgical mask against infectious aerosols is not well understood. AIM: To develop and apply a method for assessing the protection afforded by surgical masks against a bioaerosol challenge. METHODS: A dummy test head attached to a breathing simulator was used to test the performance of surgical masks against a viral challenge. Several designs of surgical masks commonly used in the UK healthcare sector were evaluated by measuring levels of inert particles and live aerosolised influenza virus in the air, from in front of and behind each mask. FINDINGS: Live influenza virus was measurable from the air behind all surgical masks tested. The data indicate that a surgical mask will reduce exposure to aerosolised infectious influenza virus; reductions ranged from 1.1- to 55-fold (average 6-fold), depending on the design of the mask. CONCLUSION: We describe a workable method to evaluate the protective efficacy of surgical masks and RPDs against a relevant aerosolised biological challenge. The results demonstrated limitations of surgical masks in this context, although they are to some extent protective.

Concepts: Infectious disease, Influenza, Avian influenza, Influenza pandemic, Pandemic, Reassortment, Masks, Bioaerosol

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This work aimed to develop an in vivo approach for measuring the duration of human bioaerosol infectivity. To achieve this, techniques designed to target short-term and long-term bioaerosol aging, were combined in a tandem system and optimized for the collection of human respiratory bioaerosols, without contamination. To demonstrate the technique, cough aerosols were sampled from two persons with cystic fibrosis and chronic Pseudomonas aeruginosa infection. Measurements and cultures from aerosol ages of 10, 20, 40, 900 and 2700 seconds were used to determine the optimum droplet nucleus size for pathogen transport and the airborne bacterial biological decay. The droplet nuclei containing the greatest number of colony forming bacteria per unit volume of airborne sputum were between 1.5 and 2.6 μm. Larger nuclei of 3.9 μm, were more likely to produce a colony when impacted onto growth media, because the greater volume of sputum comprising the larger droplet nuclei, compensated for lower concentrations of bacteria within the sputum of larger nuclei. Although more likely to produce a colony, the larger droplet nuclei were small in number, and the greatest numbers of colonies were instead produced by nuclei from 1.5 to 5.7 μm. Very few colonies were produced by smaller droplet nuclei, despite their very large numbers. The concentration of viable bacteria within the dried sputum comprising the droplet nuclei exhibited an orderly dual decay over time with two distinct half-lives. Nuclei exhibiting a rapid biological decay process with a 10 second half-life were quickly exhausted, leaving only a subset characterized by a half-life of greater than 10 minutes. This finding implied that a subset of bacteria present in the aerosol was resistant to rapid biological decay and remained viable in room air long enough to represent an airborne infection risk.

Concepts: Immune system, Bacteria, Pneumonia, Pseudomonas aeruginosa, Cystic fibrosis, Radioactive decay, Aerosol, Bioaerosol

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ABSTRACT Respiratory protection provided by a particulate respirator is a function of particle penetration through filter media and through faceseal leakage. Faceseal leakage largely contributes to the penetration of particles through respirator and compromises protection. When faceseal leaks arise, filter penetration is assumed to be negligible. The contribution of filter penetration and faceseal leakage to total inward leakage (TIL) of submicron size bioaerosols is not well studied. To address this issue, TIL values for two N95 filtering facepiece respirator (FFR) models and two surgical mask (SM) models sealed to a manikin were measured at 8 L and 40 L breathing minute volumes with different artificial leak sizes. TIL values for different size (20-800 nm, electrical mobility diameter) NaCl particles representing submicron size bioaerosols were measured using a scanning mobility particle sizer. Efficiency of filtering devices was assessed by measuring the penetration against NaCl aerosol similar to the method used for NIOSH particulate filter certification. Results showed that the most penetrating particle size (MPPS) was ∼45 nm for both N95 FFR models and one of the two SM models, and ∼350 nm for the other SM model at sealed condition with no leaks as well as with different leak sizes. TIL values increased with increasing leak sizes and breathing minute volumes. Relatively, higher efficiency N95 and SM models showed lower TIL values. Filter efficiency of FFRs and SMs influenced the TIL at different flow rates and leak sizes. Overall, the data indicate that good fitting higher efficiency FFRs may offer higher protection against submicron size bioaerosols.

Concepts: Sociology, Aerosol, Respirator, Filters, Leak, Masks, Bioaerosol, Surgical mask

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Despite the obvious importance of viral transmission and ecology to medicine, epidemiology, ecology, agriculture, and microbiology, the study of viral bioaerosols and community structure has remained a vastly underexplored area, due both to unresolved technical challenges and unrecognized importance. High-throughput, culture-independent techniques such as viral metagenomics are beginning to revolutionize the study of viral ecology. With recent developments in viral metagenomics, characterization of viral bioaerosol communities provides an opportunity for high-impact future research. However, there remain significant challenges for the study of viral bioaerosols compared to viruses in other matrices, such as water, the human gut, and soil. Collecting enough biomass is essential for successful metagenomic analysis, but this is a challenge with viral bioaerosols. Herein, we provide a perspective on the importance of studying viral bioaerosols, the challenges of studying viral community structure, and the potential opportunities for improvements in methods to study viruses in indoor and outdoor air. This article is protected by copyright. All rights reserved.

Concepts: Evolution, Biology, Microbiology, Metagenomics, Aerosol, All rights reserved, Copyright, Bioaerosol

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 Noroviruses are responsible for at least 50% of all gastroenteritis outbreaks worldwide. Noroviruses GII can infect humans via multiple routes including direct contact with an infected person, contact with fecal matter or vomitus, and with contaminated surfaces. Though norovirus is an intestinal pathogen, aerosols could, if inhaled, settle in the pharynx and later be swallowed. The aims of this study were to investigate the presence of norovirus GII bioaerosols during gastroenteritis outbreaks in healthcare facilities as well as studying the in vitro effects of aerosolization and air sampling on the noroviruses using murine norovirus as a surrogate.

Concepts: Bacteria, Constipation, Flatulence, Feces, Diarrhea, Gastroenteritis, Norovirus, Bioaerosol

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State-of-the-art bioaerosol samplers have poor collection efficiencies for ultrafine virus aerosols. This work evaluated the performance of a novel Growth Tube Collector (GTC), which utilizes laminar-flow water-based condensation to facilitate particle growth, for the collection of airborne MS2 viruses.

Concepts: Microbiology, Virus, RNA, Bacteriophage, Physical chemistry, Aerosol, Bioaerosol, CS gas

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

Concepts: Mathematics, Macaque, Respiratory system, Primate, Rhesus Macaque, Aerosol, Region, Bioaerosol

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One of the most important topics that occupy public health problems is the air quality. That is the reason why mechanical ventilation and air handling units (AHU) were imposed by the different governments in the collective or individual buildings. Many buildings create an artificial climate using heating, ventilation, and air-conditioning systems. Among the existing aerosols in the indoor air, we can distinguish the bioaerosol with biological nature such as bacteria, viruses, and fungi. Respiratory viral infections are a major public health issue because they are usually highly infective. We spend about 90% of our time in closed environments such as homes, workplaces, or transport. Some studies have shown that AHU contribute to the spread and transport of viral particles within buildings. The aim of this work is to study the characterization of viral bioaerosols in indoor environments and to understand the fate of mengovirus eukaryote RNA virus on glass fiber filter F7 used in AHU. In this study, a set-up close to reality of AHU system was used. The mengovirus aerosolized was characterized and measured with the electrical low pressure impact and the scanner mobility particle size and detected with RT-qPCR. The results about quantification and the level of infectivity of mengovirus on the filter and in the biosampler showed that mengovirus can pass through the filter and remain infectious upstream and downstream the system. Regarding the virus infectivity on the filter under a constant air flow, mengovirus was remained infectious during 10 h after aerosolization.

Concepts: Bacteria, Virus, RNA, Infection, Aerosol, Indoor air quality, HVAC, Bioaerosol

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The source, characteristics and transport of viable microbial aerosols in urban centers are topics of significant environmental and public health concern. Recent studies have identified adjacent waterways, and especially polluted waterways, as an important source of microbial aerosols to urban air. The size of these aerosols influences how far they travel, their resistance to environmental stress, and their inhalation potential. In this study, we utilize a cascade impactor and aerosol particle monitor to characterize the size distribution of particles and culturable bacterial and fungal aerosols along the waterfront of a New York City embayment. We seek to address the potential contribution of bacterial aerosols from local sources and to determine how their number, size distribution, and taxonomic identity are affected by wind speed and wind direction (onshore vs. offshore). Total culturable microbial counts were higher under offshore winds (average of 778 CFU/m(3) ± 67), with bacteria comprising the majority of colonies (58.5%), as compared to onshore winds (580 CFU/m(3) ± 110) where fungi were dominant (87.7%). The majority of cultured bacteria and fungi sampled during both offshore winds (88%) and onshore winds (72%) were associated with coarse aerosols (>2.1 µm), indicative of production from local sources. There was a significant correlation (p < 0.05) of wind speed with both total and coarse culturable microbial aerosol concentrations. Taxonomic analysis, based on DNA sequencing, showed that Actinobacteria was the dominant phylum among aerosol isolates. In particular, Streptomyces and Bacillus, both spore forming genera that are often soil-associated, were abundant under both offshore and onshore wind conditions. Comparisons of bacterial communities present in the bioaerosol sequence libraries revealed that particle size played an important role in microbial aerosol taxonomy. Onshore and offshore coarse libraries were found to be most similar. This study demonstrates that the majority of culturable bacterial aerosols along a New York City waterfront were associated with coarse aerosol particles, highlighting the importance of local sources, and that the taxonomy of culturable aerosol bacteria differed by size fraction and wind direction.

Concepts: Bacteria, Eukaryote, Fungus, Aerosol, Wind, Streptomyces, Actinobacteria, Bioaerosol