Bacterial Aerosols Research Articles

Preliminary insight into the relationship between bioaerosols and urban environment obtained from the COVID-19 self-quarantine period in the Tokyo metropolitan area

Anthropogenic activities and meteorological conditions influence the composition of urban bioaerosols. The COVID-19 epidemic drastically reduced anthropogenic activities in the metropolitan areas of Japan in 2020. This study examined inter-day fluctuations in airborne bacterial and fungal compositions in Tokyo, Japan, between April and June 2020, under exceptionally unusual conditions where the movement of people and economic activity had been greatly reduced. The result showed, as expected, that local meteorological factors, especially wind and precipitation, substantially impacted emissions and changes in bacterial and fungal aerosols. However, we found that variations in the composition of urban bioaerosols could potentially be affected by anthropogenic influences, such as the concentrations of nitrogen oxides, ozone, and particulate matter, and human density. Although such factors are not as influential as wind and precipitation, it was shown for the first time that drastic changes in human activities within an area can affect the dynamics of bioaerosols. This could be a finding that should be considered for public health issues related to air quality in changing urban areas such as fast-growing cities.

Characterization of fungal communities in aerosols: Coastal waters vs. open oceans

Bioaerosols have an important influence on both the environment and human health. Current research on bioaerosols more focuses on bacterial aerosols, while the research of fungal aerosols could not be neglected, especially in marine environments. We present a study on the spatial distribution of fungal communities in aerosols over the South Yellow Sea (SYS), the East China Sea (ECS) and the northwestern Pacific (NWP) in autumn, further taking into account the influences of particle size differences and environmental factors. We found that the fungal concentrations at the junction of the South Yellow Sea and the East China Sea (SYS-ECS) were significantly greater than those at the junction of the East China Sea and the NWP (ECS-NWP) and the NWP (NWP1, NWP2, NWP5, and NWP9) (p < 0.05). Spatial differences in the richness and diversity of fungal communities were observed across different sea areas. Additionally, both the concentration and richness of fungal aerosols gradually decreased with increasing off-coast distance, suggesting that the influence of terrestrial sources on fungal aerosols over coastal waters was higher than open oceans. According to CCA (canonical correspondence analysis), the fungal community structures in the northern China marginal seas (NCMS) were influenced by the water-soluble ions F−, NO3−, and Ca2+, which primarily originated from anthropogenic activities, whereas wind speed exerted a significant impact on fungal community structure in the NWP. These results illustrate that the community structures of fungal aerosols depend on sampling site locations, source areas, particle size, and transport mechanisms. This research contributes to the understanding of fungal aerosols over the marine environment and reveals the impacts of environmental factors on fungal aerosols.

Exposure to Bacterial and Fungal Aerosol in the University Library – A Case Study

Exposure to Bacterial and Fungal Aerosol in the University Library – A Case Study

Health Risk Assessment and Covid-19 Infection Rate by Using Bacterial Aerosol in Healthcare Workers in a Tertiary Care Hospital in Thailand During SARS-CoV-2 Pandemic

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide transmission and healthcare worker is the risk group. Therefore, the infection rate and health risk assessment from exposure to airborne transmission for healthcare workers were performed. Methods: This cross-sectional study was carried out on 106 healthcare workers at four selected service areas in Songklanagarind Hospital, Thailand, from February to September 2021. The N6 impactor was used with simultaneous measurement of temperature, relative humidity, and wind speed. The general characteristics of subjects and hospitals were collected by questionnaire and presented by descriptive statistics. Results: Most of the participants were female and they worked more than 8 hours per day. The bacteria concentration was highest in the Pediatric Outpatient Department (1837.46±177.52 cfu/m3). The lowest chronic daily intake and hazard quotient with no threshold (4.86±3.81, 95%CI: 3.59, 6.13) were at Covid-19 Intensive Care Unit - due to negative pressure ventilation in this room was effective in reducing the airborne concentration of the pathogens. Overall, the hospital’s hazard index with no threshold (30.87±35.25, 95%CI: 23.91, 37.83) was higher than 1.0, indicating that bacterial bioaerosol may affect healthcare workers’ health. The highest confirmed Covid-19 case was at Acute Respiratory Infection Clinic (19.29±10.67 cases/week). The probability of infection by SARS-CoV-2 in healthcare workers was high at Acute Respiratory Infection Clinic (1.0) and Covid-19 Intensive Care Unit (0.998±0.002, 95%CI: 0.998, 0.999). Conclusion: Therefore, inhalation reference concentration for hospitals should be as low as possible and appropriate ventilation systems should be implemented with adherence to standards to protect healthcare workers.

Comparison of bioaerosol release characteristics between windrow and trough sludge composting plants: Concentration distribution, community evolution, bioaerosolization behaviour, and exposure risk

Windrow and trough composting are two mainstream composting methods, but the effect of composting methods on bioaerosol release from sludge composting plants is unclear. The study compared the bioaerosol release characteristics and exposure risks between the two composting methods. The results showed that the bacterial aerosol concentrations in the windrow composting plant ranged from 14,196 to 24,549 CFU/m3, while the fungal aerosol concentrations in the trough composting plant reached 5874 to 9284 CFU/m3; there were differences in the microbial community structures between the two sludge composting plants, and the composting method had a greater effect on bacterial community evolution than on fungal community evolution. The biochemical phase was the primary source of the bioaerosolization behaviour of the microbial bioaerosols. In the windrow and trough composting plants, the bacterial bioaerosolization index ranged from 1.00 to 999.28 and from 1.44 to 24.57, and the fungal bioaerosolization index ranged from 1.38 to 1.59 and from 0.34 to 7.72, respectively. Bacteria preferentially aerosolized mainly in the mesophilic stage, while the peak of the fungal bioaerosolization index appeared in the thermophilic stage. The total non-carcinogenic risks for bacterial aerosols were 3.4 and 2.4, while those for fungi were 1.0 and 3.2 in the trough and windrow sludge composting plants, respectively. Respiration is the main exposure pathway for bioaerosols. It is necessary to develop different bioaerosol protection measures for different sludge composting methods. The results of this study provided basic data and theoretical guidance for reducing the potential risk of bioaerosols in sludge composting plants.

Bioaerosol Identification by Wide Particle Size Range Single Particle Mass Spectrometry

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

Structural design and development of multilayered polymeric nanofibrous membrane for multifaceted air filtration/purification applications

ABSTRACT Developed a bilayered nanofibrous membrane, aimed to achieve a new class of air filtering media that can capture particulate matter, microbes and can also adsorb the harmful toxic gaseous components like formaldehyde (primary indoor pollutant). A layer of oriented nanofibers prepared via coaxial electrospinning with poly(m-phenylene isophthalamide) as core, polyacrylonitrile/polyethylenimine blended polymer as shell and another layer of randomly aligned nanofibers (polyacrylonitrile-silver nanoparticle nanofibers produced using single-nozzle electrospinning) were put together, to provide stable porous structure and induce multilevel filtration. The successful synthesis of this robust coaxial-based nanofibrous filter medium would not only make it a promising candidate for air filtration, but it will provide a new insight into designing and fabricating composite coaxial nanofiber-based membranes by incorporating various functional materials into shell for toxic gas adsorption related applications and the core can be of a mechanically robust material to address the easily collapsing cavity structure of nanofibers. The results revealed that the developed filter with superior mechanical property (11.88 MPa by virtue of poly(m-phenylene isophthalamide) fiber macromolecule that existed as rigid skeletal structure) can provide high removal efficiencies of 99.23% toward particulate matter, 99.6% toward bacterial aerosols, adsorb formaldehyde an indoor toxic gaseous pollutant and have potential antimicrobial effects against Escherichia coli and Bacillus subtilis while maintaining low pressure drop of 53.03 MPa, which to the best of our knowledge, has never been accomplished with a single filter medium before.

Spatial distribution of airborne bacterial communities in caged poultry houses

ABSTRACT Microbial aerosols in intensive broiler houses whose species and concentrations are closely related to human health are ubiquitous. Based on 16S rRNA gene sequencing, the aim of this study was to investigate the spatial distribution and diversity of bacterial aerosols in the air of broiler houses. Significant spatial variations in airborne bacterial concentrations were observed inside the poultry farmhouse. The results indicated that bacteria in the air samples could be grouped into a total of 1,674 OTUs. Alpha diversity analysis showed that the diversity of the microbial community at the entry of the broiler house was higher than that at the middle or the rear (p < 0.01). The Sankey diagram illustrated species dynamic changes in Proteobacteria, Firmicutes, and Actinobacteria among the different locations. From the aspect of LEfSe (LDA Effect Size) analysis, we discovered that the abundance of Planctomycetes was significantly higher in the entry than in the rear and middle. This study shows the spatial distribution of the entire bacterial community in intensive broiler houses, which offers a new perspective for studying airborne total bacteria in those environments. Implications: The bacteria contained in air aerosols from poultry houses are closely connected to animal health and production. This study aimed to investigate the spatial distribution and diversity of bacterial aerosols in the air of broiler houses. The results observed that bacterial aerosol concentrations in the examined broilers house varied greatly at different positions, and a significantly higher exposure to bacterial aerosol was observed at the middle than at the other positions (p < 0.05). The alpha diversity analysis showed that the diversity of the microbial community at the entry of the broiler house was higher than that at the middle or the rear (P<0.01). Sankey diagram illustrated species dynamic changes of Proteobacteria, Firmicutes and Actinobacteria among the different locations. The microbial communities in genus level in the samples of entry and rear were closer, while the species diversity of middle and rear samples in chicken house was highly similar (P>0.05). Altogether, results revealed that the effects of spatial factors on the diversity and abundance of bacteria in the air of closed-cage broiler houses, which poses a potential threat to the health of animals and workers in those environments.

Particle Size Matters: Distribution, Source, and Seasonality Characteristics of Airborne and Pathogenic Bacteria in Wastewater Treatment Plants

Wastewater treatment plants (WWTPs) are a crucial source of bioaerosols, which account for both environmental and health hazards. Although various culture-based studies on bioaerosols have been reported, little knowledge remains about distribution and potential risks for more omnipresent non-culturable bacterial aerosols. Here, in summer, an eight-stage Andersen air sampler was applied to capture particles of various sizes from the atmospheric environment of eight treatment units from two WWTPs in northeastern China. Particles of various sizes in aeration tank (AT) were sampled in autumn and winter. The abundance and community composition of the bacterial aerosols were investigated using 16S rRNA gene sequencing. In order to explore the importance of particle size on community composition of bacterial aerosols, this study investigated the particle size distribution of bacterial aerosols in different treatment units. The results indicated that the sludge dewatering room was the major source of bacterial aerosols in both WWTPs, with the abundance of stage VII (0.65–1.1 μm) demonstrating a 4-fold to 9-fold increase when compared to any other treatment unit. The highest relative abundance of bacterial aerosols was in autumn, while the lowest was found in winter. However, most particles detected in autumn were larger than 4.7 µm in diameter, while submicron particles (less than 1.1 µm, over 40%) were detected primarily in winter. The most 15 dominant bacterial aerosol genera in were observed at submicron level, and about half of the genera (6 and 8) were detected as human pathogens, suggesting their easier penetration to human respiratory tracts. This study demonstrates that size distribution characteristics should be crucial information for the comprehensive assessment of the potential health risks of bacterial aerosols from WWTPs.

Effect of temperature and humidity on dynamics and transmission of Pseudomonas amygdali pv. lachrymans aerosols.

Cucumber angular leaf spot (ALS) disease, caused by Pseudomonas amygdali pv. lachrymans (Pal), is an emerging disease with a high incidence that causes severe damage to cucumber worldwide. Bacterial aerosols play a crucial role in the epidemiology of greenhouse ALS disease. However, little is known about the influence of temperature and relative humidity (RH) on the dynamics of Pal in aerosols. A study was conducted to investigate the relationships between the concentration of Pal aerosols and their dependence on temperature and RH in aerosol chambers and greenhouses. The results demonstrated that temperature and RH are both significant factors influencing the release amount, survival time and infectivity of Pal in aerosols, while RH has a greater influence on particle size than temperature across the range of conditions tested. The release amount and survival time of Pal in aerosols under high RH (95%) and low temperature (≤ 25°C) conditions were significantly higher than those under low RH (35%) and high temperature (35°C) conditions. The highest release amount of Pal aerosol (96 CFU/m3) and highest survival rate (98.41%) were found at 18°C and 95% RH, while the highest disease index (DI = 60.9) caused by Pal aerosol was found at 25°C and 95% RH. In addition, Pal aerosols presented a larger diameter (4.7->7.0 μm) under high RH (95% RH) than under dry conditions (≤ 65% RH). These findings will play a crucial role in elucidating the influence of environmental parameters on the dynamics and transmission of Pal in aerosols. Based on our findings, preliminary recommendations for controlling airborne Pal spread involve controlling air temperature and RH, which will contribute to the effective alleviation and control of cucumber ALS disease.

Assessment of Bacterial Aerosols in a Herbal Processing Plant

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

COMPARATIVE ASSESSMENT OF BACTERIAL PERMEABILITY OF A PERSONAL PROTECTIVE RESPIRATORY EQUIPMENT AT DIFFERENT DURATIONS OF ITS CONTINUOUS OPERATION.

The aim: To establish the level of antibacterial protection of the studied personal protective respiratory equipment set and its main components and compare antibacterial resistance of the personal protective respiratory equipment set in the presence and absence of filtering components. Materials and methods: The proposed methodology for assessing biological protection parameters is based on testing the permeability of personal respiratory protection equipment for bacteria by the method of serial dilutions. Also additional culturing of separate components of the protective set on a separate media is carried out. The experiment was also repeated in the absence of filtering elements and when they were replaced by gauze masks. Results: The use of a fully equipped pneumatic helmet counteracted the penetration of the bacterial aerosol, which was manifested in the absence of growth on the media. The results obtained with the full configuration, as well as the indicators of the spread of bacteria when removing the filter elements and replacing them with gauze masks, showed that the device creates sufficient positive air pressure inside. The latter becomes a restraining factor that does not allow microorganisms to penetrate through the lower circuit. Conclusions: Increasing the duration of continuous operation of the conceptual model up to 24 hours, increasing the bacterial load on the filters do not lead to a deterioration in the properties of antibacterial protection. Bacterial aerosol did not penetrate into the inner space of pneumatic helmet.

EO-based mouthwashes: Is there something that should be known?

The possibility to utilize the antibacterial and antibiofilm potential of essential oils (EOs) in dentistry is recognized and best seen in the design of EO-based mouthwashes. The up-to-date results, obtained with the most commonly used formulation being consisted of thymol, eucalyptol, menthol, and methyl salicylate (Listerine), proved its efficacy against plaque and gingival inflammation. However, novel alcohol-free products remain to be further investigated. Commercially available mouthwash containing curcumin, clove oil, mentha oil, eucalyptol, thymol and tea tree oil, and the mouthwash based on ginger EO (a-zingiberene, b-bisabolene, b-sesquiphellandrene, curcumene), reduced plaque index and improved periodontal status of the patients. The plaque index was also reduced and overall healing was improved after the surgical removal of the third molar by mouthwash containing John wort oil. In addition, Cinnamomum zeylanicum EO-based mouthwash and mouthwash containing peppermint oil were efficient against stomatitis and xerostomia, respectively. In addition to beneficial effects achieved in the mouth, i.e. at the appropriate site of application, novel investigations pointed-out that EO-based mouthwashes could be recognized as efficient in the reduction of bacterial and viral aerosols. This has been shown for Listerine, and for several mouthwashes containing following active substances of plants' EO origin: a-farnesene, b-farnesene, farnesol, nerolidol, a-bulnesene, eremanthin, b-sesquiphellandrene, spiroether, cinnamylacetate, cinnamaldehyde, eugenol, menthol, and carvacrol. This finding could be of special interest, in order to be included in further clinical studies related to COVID -19 pandemic.

Protective Effect of 0.1% Chlorhexidine Gluconate Solution Pre-Rinse against Oral Bacteria and Bacterial Aerosol Contamination during Ultrasonic Scaling

Objectives: This study was conducted to determine the antibacterial effect of 0.1% chlorhexidine gluconate solution (CGS) against oral microorganism and to confirm contamination of personal protective equipment and environment of dental clinic by bacterial aerosol during ultrasonic scaling. Methods: Scaling was performed by a dental hygienist after 0.1% CGS pre-rinse to a total of 18 healthy subjects without oral inflammation. Samples were taken from personal protective equipment and environment to confirm contamination by bacterial aerosol. Results: The most contaminated area with bacterial aerosol was the dental hole towel of patient and followed by the chest, cap, gloves, and dental apron of personal protective equipment. The areas with high CGS pre-rinse effect after scaling were cap, gloves, ultrasonic scaler handle, and dental hole towel. Conclusions: 0.1% CGS pre-rinse is an effective method to consistently reduce the risk of periodontitis and contamination by bacterial aerosol in dental treatment including scaling.

Number size distribution of bacterial aerosols in terrestrial and marine airflows at a coastal site of Japan

Size-differentiated concentration of bacterial aerosols is essential for investigating their dissemination via the atmosphere. In this study, the number size distribution of bacterial aerosols was measured at a coastal site in southwestern Japan (32.324°N, 129.993°E) using a size-segregated eight-stage (>11, 7.0–11, 4.7–7.0, 3.3–4.7, 2.1–3.3, 1.1–2.1, 0.65–1.1, and 0.43–0.65μm) sampler. The results showed that the distribution differed according to the source areas: terrestrial air, oceanic air, or a combination of the two. The distribution in the long-distance transported terrestrial air from the Asian continent was monomodal, with a peak of 3.3–4.7 μm. The distribution in local land breeze air was bimodal, with the peaks at 0.43–1.1 and 3.3–4.7 μm. A similar bimodal distribution was encountered when the local island air and long-distance transported terrestrial air mixed. In contrast, the size distribution did not show clear peaks in the air from either nearby or remote marine areas. According to the air mass backward trajectories, the further the distance the air moved in the 72 h before arriving at the site, the lower the concentration of total bacterial aerosols. The estimation of dry deposition fluxes of bacterial cells showed that the deposition was dominated by cells larger than 1.1 μm with a relative contribution from 70.5 % to 93.7 %, except for the local land breeze cases, where the contributions in the size ranges larger and smaller than 1.1 μm were similar. These results show the distinctive number size distributions and removal processes of bacterial aerosols in different types of air. In addition, they indicate that size-dependent characteristics of airborne bacteria should be considered when studying their activities and roles in the atmospheric environment.

Assessment of Seasonal Variation of Microbial Aerosol and Gaseous Emissions from Wastewater Treatment Plant of Morche Khort Industrial Town

Introduction: Wastewater contains a large number of pathogenic and non-pathogenic microorganisms that can become bioaerosols during the treatment processes in different units of the treatment plant, and pose a risk to workers and nearby residents. In this study, the release of bioaerosols from a wastewater treatment plant of Morche Khort Industrial Town was investigated.&#x0D; Materials and Methods: Sampling was actively performed according to EPA standard, in two seasons of spring and summer in 2018-2019, by an environmental sampling pump with a flow rate of 15 l/min and a single-stage impactor. The data were analyzed by SPSS software version 2020.&#x0D; Results: The study results showed that the mean number of bacteria in the aeration tank was significantly higher than other points. The mean number of fungi in the aeration pond with 144 CFU/m3 had the highest concentration, and no fungal bioaerosol was observed 500 m downstream. Regarding the emission of H2S, CH4, and VOC gases, the anaerobic tank had the highest emission of these gases.&#x0D; Conclusion: Wastewater treatment plants (WWTPs) with activated sludge treatment technology and an aeration system can lead to an increase in the concentration of bacterial and fungal aerosols around the units and in surrounding areas.

Indoor bacterial and fungal aerosols as predictors of lower respiratory tract infections among under-five children in Ibadan, Nigeria.

This study aimed to investigate the association between exposure to diverse indoor microbial aerosols and lower respiratory tract infections (LRTI) among children aged 1 to 59months in Ibadan, Nigeria. One hundred and seventy-eight (178) hospital-based LRTI cases among under-five children were matched for age (± 3months), sex and geographical location with 180 community-based controls (under-five children without LRTI). Following consent from caregivers of eligible participants, a child's health questionnaire, clinical proforma and standardized home-walkthrough checklist were used to collect data. Participant homes were visited and sampled for indoor microbial exposures using active sampling approach by Anderson sampler. Indoor microbial count (IMC), total bacterial count (TBC), and total fungal count (TFC) were estimated and dichotomized into high (> median) and low (≤ median) exposures. Alpha diversity measures including richness (R), Shannon (H) and Simpson (D) indices were also estimated. Conditional logistic regression models were used to test association between exposure to indoor microbial aerosols and LRTI risk among under-five children. Significantly higher bacterial and fungal diversities were found in homes of cases (R = 3.00; H = 1.04; D = 2.67 and R = 2.56; H = 0.82; D = 2.33) than homes of controls (R = 2.00; H = 0.64; D = 1.80 and R = 1.89; H = 0.55; D = 1.88) p < 0.001, respectively. In the multivariate models, higher categories of exposure to IMC (aOR = 2.67, 95% CI 1.44-4.97), TBC (aOR = 2.51, 95% CI 1.36-4.65), TFC (aOR = 2.75, 95% CI 1.54-4.89), bacterial diversity (aOR = 1.87, 95% CI 1.08-3.24) and fungal diversity (aOR = 3.00, 95% CI 1.55-5.79) were independently associated with LRTI risk among under-five children. This study suggests an increased risk of LRTI when children under the age of five years are exposed to high levels of indoor microbial aerosols.

Distribution characteristics and potential risks of bacterial aerosol in waste transfer station

The waste transfer station (WTS) is an important link in the transfer of municipal solid waste (MSW) between the community and disposal terminals. While WTSs facilitate waste collection in communities, odorous gases and bioaerosols can escape from them, thereby negatively affecting their surroundings. In this study, the concentration, particle size distribution, pathogen population, and health risks of bioaerosols were analyzed at different locations in a transfer station. The results showed that the highest viable bacterial aerosol concentration was 10,353 ± 3701 CFU/m3, which was at 5 m from the disposal site. Fifty-three bacterial species, including pathogens, were detected. Of these, 39 were human pathogenic bacteria directly originating from the WTS. Furthermore, health risk assessments indicated unacceptable levels of non-carcinogenic risk for operational workers caused by bacterial aerosols of the WTS work area. In addition, bacterial aerosols may pose a severe health risk to children within a 15 m area of the WTS. The results of this study provide a scientific basis to control and reduce the risk associated with bioaerosol exposure in solid WTSs.

Seasonal dynamics in bacterial communities of closed-cage broiler houses.

The bacteria contained in air aerosols from poultry houses are closely connected to animal health and production. This study aimed to investigate the seasonal factors on microbial aerosol concentration, particle size and bacterial spectrum composition inside a closed-cage broiler house. Then, 16S rDNA sequencing technology was applied to analyze the characteristics of bacterial abundance and diversity. The results indicated that the concentration of bacterial aerosol in the broiler house varied significantly in different seasons, with a concentration range of 5.87-15.77 × 103 CFU/m3, and the highest and lowest concentrations in the summer and winter, respectively. Microbiological analysis showed that the proportion of Gram-negative bacteria in autumn was significantly higher than that in summer (P < 0.05). In addition, the floral structure of potential pathogenic bacterial genera also differed by season. Escherichia-Shigella, Streptococcus, Acinetobacter, Pseudomonas were identified in the bacterial aerosols. Importantly, the relative abundance of Firmicutes in spring and autumn was much higher. In contrast, the relative abundance of Proteobacteria in spring and autumn was lower than that in summer and winter. Altogether, results revealed the effects of seasonal factors on the diversity and abundance of bacteria and the distribution characteristics of major opportunistic pathogens in the air of closed-cage broiler houses. These results will provide important information for exploring the potential risk of aerosols from poultry houses all four seasons.

Impact of Different Air Pollutants (PM10, PM2.5, NO2, and Bacterial Aerosols) on COVID-19 Cases in Gliwice, Southern Poland.

Many studies have shown that air pollution may be closely associated with increased morbidity and mortality due to COVID-19. It has been observed that exposure to air pollution leads to reduced immune response, thereby facilitating viral penetration and replication. In our study, we combined information on confirmed COVID-19 daily new cases (DNCs) in one of the most polluted regions in the European Union (EU) with air-quality monitoring data, including meteorological parameters (temperature, relative humidity, atmospheric pressure, wind speed, and direction) and concentrations of particulate matter (PM10 and PM2.5), sulfur dioxide (SO2), nitrogen oxides (NO and NO2), ozone (O3), and carbon monoxide (CO). Additionally, the relationship between bacterial aerosol (BA) concentration and COVID-19 spread was analyzed. We confirmed a significant positive correlation (p < 0.05) between NO2 concentrations and numbers of confirmed DNCs and observed positive correlations (p < 0.05) between BA concentrations and DNCs, which may point to coronavirus air transmission by surface deposits on bioaerosol particles. In addition, wind direction information was used to show that the highest numbers of DNCs were associated with the dominant wind directions in the region (southern and southwestern parts).