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Experiments were conducted in a controlled environmental chamber (S1 Fig) designed to simulate an office room [15]. (2015) Chamber Bioaerosol Study: Outdoor Air and Human Occupants as Sources of Indoor Airborne Microbes.

Microorganisms are ubiquitous and highly diverse in the atmosphere. Despite the potential impacts of airborne bacteria found in the lower atmosphere over the Southern Ocean (SO) on the ecology of Antarctica and on marine cloud phase, no previous region-wide assessment of bioaerosols over the SO has been reported. We conducted bacterial profiling of boundary layer shipboard aerosol samples obtained during an Austral summer research voyage, spanning 42.8 to 66.5°S. Contrary to findings over global subtropical regions and the Northern Hemisphere, where transport of microorganisms from continents often controls airborne communities, the great majority of the bacteria detected in our samples were marine, based on taxonomy, back trajectories, and source tracking analysis. Further, the beta diversity of airborne bacterial communities varied with latitude and temperature, but not with other meteorological variables. Limited meridional airborne transport restricts southward community dispersal, isolating Antarctica and inhibiting microorganism and nutrient deposition from lower latitudes to these same regions. A consequence and implication for this region’s marine boundary layer and the clouds that overtop it is that it is truly pristine, free from continental and anthropogenic influences, with the ocean as the dominant source controlling low-level concentrations of cloud condensation nuclei and ice nucleating particles.

This study calculates and elucidates the minimum size of respiratory particles that are potential carriers of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); furthermore, it evaluates the aerosol generation potential of SARS-CoV-2. The calculations are based on experimental results and theoretical models. In the case of maximum viral-loading derived from experimental data of COVID-19 patients, 8.97 × 10−5% of a respiratory fluid particle from a COVID-19 patient is occupied by SARS-CoV-2. Hence, the minimum size of a respiratory particle that can contain SARS-CoV-2 is calculated to be approximately 9.3 μm. The minimum size of the particles can decrease due to the evaporation of water on the particle surfaces. There are limitations to this analysis: (a) assumption that the viruses are homogeneously distributed in respiratory fluid particles and (b) considering a gene copy as a single virion in unit conversions. However, the study shows that high viral loads can decrease the minimum size of respiratory particles containing SARS-CoV-2, thereby increasing the probability of aerosol generation of the viruses. The aerosol generation theory created in this study for COVID-19 has the potential to be applied to other contagious diseases that are caused by respiratory infectious microorganisms.

* Emission of microbe from local environments is a main source of bioaerosols. * Regional transport is another important source of the bioaerosols. * There are many factors affecting the diffusion and transport of bioaerosols. * Source identification method uncovers the contribution of sources of bioaerosols. Recent pandemic outbreak of the corona-virus disease 2019 (COVID-19) has raised widespread concerns about the importance of the bioaerosols. They are atmospheric aerosol particles of biological origins, mainly including bacteria, fungi, viruses, pollen, and cell debris. Bioaerosols can exert a substantial impact on ecosystems, climate change, air quality, and public health. Here, we review several relevant topics on bioaerosols, including sampling and detection techniques, characterization, effects on health and air quality, and control methods. However, very few studies have focused on the source apportionment and transport of bioaerosols. The knowledge of the sources and transport pathways of bioaerosols is essential for a comprehensive understanding of the role microorganisms play in the atmosphere and control the spread of epidemic diseases associated with them. Therefore, this review comprehensively summarizes the up to date progress on the source characteristics, source identification, and diffusion and transport process of bioaerosols. We intercompare three types of diffusion and transport models, with a special emphasis on a widely used mathematical model. This review also highlights the main factors affecting the source emission and transport process, such as biogeographic regions, land-use types, and environmental factors. Finally, this review outlines future perspectives on bioaerosols.

Purpose The concentration and distribution characteristics of airborne bacteria and fungi were assessed at municipal solid-waste processing and disposal facilities (SWPDFs) of Tehran (Arad Kouh Site). Methods Air samples were obtained from the indoor air of a laboratory and refectory as well as from the air surrounding a conveyor belt, rotary screen, and bailer. Sampling was conducted according to the standard procedure to determine two bacterial species ( Klebsiella spp. and Staphylococcus aureus ), total bacteria and fungi, and Aspergillus fumigates . Results The maximum concentration of Staphylococcus aureus was in the air surrounding the conveyer belt with the average of 993.2 CFU/m 3 . The highest concentrations of total fungi (4958.8 CFU/m 3 ) and Aspergillus fumigates (2114 CFU/m 3 ) were measured in the air surrounding the rotary screen. The mean concentrations of bacterial bioaerosols in a more contaminated sampling location in summer and winter were 1687.6 and 1479.4 CFU/m 3 , respectively. Conclusions There were significant differences between the concentration of bioaerosols in cold and warm seasons. The concentrations of bioaerosols in the air surrounding the rotary screen and conveyer belt were significantly more than those in other sampling locations, but were within the recommended maximum of 10 3 and 10 4 CFU/m 3 .

Bioaerosols are biologically originated particles present in the atmosphere that can be formed from any process involving biological materials. They comprise of both living and non-living components including organisms, dispersal methods of organisms, and excretions. Bioaerosols such as airborne bacteria, fungal spores, pollen, and others possess diverse characteristics and effects. A large gap exists in the scientific understanding of the overall physical characteristics and measurement of bioaerosols. Consequently, this review aims to devise an appropriate approach to generate more scientific knowledge of bioaerosols. In addition to comparisons and discussions about the various factors affecting bioaerosols, sampling, handling, and the application of various devised analytical techniques, this review offers insight into the current state of bioaerosol research. The review focuses on instrumental and methodical strategies to understand bioaerosol measurement. Numerous studies have investigated conventional methods, advanced methods, and real-time methods that can be applied for bioaerosol monitoring. Each method is different in terms of working principle, characteristics, sensitivity, and efficiency. For the first time, this review explains and compares different methods of conventional, offline, online, and real-time detection methods of bioaerosols based on their working principles, sensitivity, and efficiency on a single platform. This will provide a clear concept and better options for selecting the appropriate method based on the research proposal. Furthermore, recent advances are summarized, and future outlooks are emphasized for bioaerosol identification and categorization. This study also encourages developing affordable and standardized methods to avoid the inter-laboratory and sampling variability to obtain a better understanding and comparison of bioaerosol measurements worldwide. Nevertheless, this work can assist researchers in selecting appropriate methods for bioaerosol measurement and investigation.

The aim of the literature review was to describe the environments where the presence of airborne Staphylococcus aureus was confirmed and to catalogue the most often used methods and conditions of bioaerosol sampling to identify the bacteria. The basis for searching of studies on S. aureus in the bioaerosol in different environments was PubMed database resources from the years 1990–2019 (May). The review included studies which were carried on in selected environments: hospitals and other health care facilities, large-scale animal breeding, wastewater treatment plants, residential areas, educational institutions, and other public places. The highest concentrations and genetic diversity of identified S. aureus strains, including MRSA (methicillin-resistant S. aureus ), have been shown in large-scale animal breeding. The role of the airborne transmission in dissemination of infection caused by these pathogens is empirically confirmed in environmental studies. Commonly available, well-described, and relatively inexpensive methods of sampling, identification, and subtyping guarantee a high reliability of results and allow to obtain fast and verifiable outcomes in environmental studies on air transmission routes of S. aureus strains.

Condensed microdroplets play a prominent role in living nature, participating in various phenomena, from water harvesting by plants and insects to microorganism migration in bioaerosols. Microdroplets may also form regular self-organized patterns, such as the hexagonally ordered breath figures on a solid surface or levitating monolayer droplet clusters over a locally heated water layer. While the breath figures have been studied since the nineteenth century, they have found a recent application in polymer surface micropatterning (e.g. for superhydrophobicity). Droplet clusters were discovered in 2004, and they are the subject of active research. Methods to control and stabilize droplet clusters make them suitable for the in situ analysis of bioaerosols. Studying life in bioaerosols is important for understanding microorganism origins and migration; however, direct observation with traditional methods has not been possible. We report preliminary results on direct in situ observation of microorganisms in droplet clusters. We also present a newly observed transition between the hexagonally ordered and chain-like states of a droplet cluster. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

Despite extensive efforts toward the characterization of submicron aerosols at ground level in the megacity of Beijing, our understanding of aerosol sources and processes at high altitudes remains low. Here we conducted a 3-month real-time measurement of non-refractory submicron aerosol (NR-PM.sub.1) species at a height of 260 m from 10 October 2014 to 18 January 2015 using an aerosol chemical speciation monitor. Our results showed a significant change in aerosol composition from the non-heating period (NHP) to the heating period (HP). Organics and chloride showed clear increases during HP due to coal combustion emissions, while nitrate showed substantial decreases from 28 to 15-18 %. We also found that NR-PM.sub.1 species in the heating season can have average mass differences of 30-44 % under similar emission sources yet different meteorological conditions. Multi-linear engine 2 (ME-2) using three primary organic aerosol (OA) factors as constraints, i.e., fossil-fuel-related OA (FFOA) dominantly from coal combustion emissions, cooking OA (COA), and biomass burning OA (BBOA) resolved from ground high-resolution aerosol mass spectrometer measurements, was applied to OA mass spectra of ACSM. Two types of secondary OA (SOA) that were well correlated with nitrate and chloride-CO, respectively, were identified. SOA played a dominant role in OA during all periods at 260 m although the contributions were decreased from 72 % during NHP to 58-64 % during HP. The SOA composition also changed significantly from NHP to HP. While the contribution of oxygenated OA (OOA) was decreased from 56-63 to 32-40 %, less oxidized OOA (LO-OOA) showed a large increase from 9-16 to 24-26 %. COA contributed a considerable fraction of OA at high altitude, and the contribution was relatively similar across different periods (10-13 %). In contrast, FFOA showed a large increase during HP due to the influences of coal combustion emissions. We also observed very different OA composition between ground level and 260 m. Particularly, the contributions of COA and BBOA at the ground site were nearly twice those at 260 m, while SOA at 260 m was ∼ 15-34 % higher than that at ground level. Bivariate polar plots and back-trajectory analysis further illustrated the different source regions of OA factors in different seasons.

Background: The spread of influenza and highly pathogenic avian influenza (H5N1) presents a significant threat to human health. Avian influenza outbreaks in downwind areas of Asian dust storms (ADS) suggest that viruses might be transported by dust storms. Objectives: We developed a technique to measure ambient influenza and avian influenza viruses. We then used this technique to measure concentrations of these viruses on ADS days and background days, and to assess the relationships between ambient influenza and avian influenza viruses, and air pollutants. Methods: A high-volume air sampler was used in parallel with a filter cassette to evaluate spiked samples and unspiked samples. Then, air samples were monitored during ADS seasons using a filter cassette coupled with a real-time quantitative polymerase chain reaction (qPCR) assay. Air samples were monitored during ADS season (1 January to 31 May 2006). Results: We successfully quantified ambient influenza virus using the filtration/real-time qPCR method during ADS days and background days. To our knowledge, this is the first report describing the concentration of influenza virus in ambient air. In both the spiked and unspiked samples, the concentration of influenza virus sampled using the filter cassette was higher than that using the high-volume sampler. The concentration of ambient influenza A virus was significantly higher during the ADS days than during the background days. Conclusions: Our data imply the possibility of long-range transport of influenza virus.