Evaluation of exposure-response relationships for health effects of microbial bioaerosols - A systematic review

Characterization of bioaerosol exposures in wastewater treatment plant workers and serum levels of lung and inflammatory markers

Wastewater treatment plant (WWTP) workers are exposed to bioaerosols containing bacteria, fungi, and endotoxin, potentially posing health risks to workers. This study quantified personal exposure levels to airborne bacteria and fungi, endotoxin, and dust among 44 workers during two seasons at four WWTPs. Associations between the exposure measurements and serum levels of biomarkers CRP, SAA, and CC16 were also assessed. The potential deposition of viable microorganisms in workers' airways were explored using stationary fractionating samplers. Microbial communities were characterized using long-read nanopore amplicon sequencing and MALDI-TOF mass spectrometry to identify species, including pathogenic or allergenic microorganisms. We found that bacterial and fungal exposure levels were significantly associated with work task (p < 0.001 and p = 0.00041, respectively), with high exposure variability within and between tasks. Workshop, sewer system inspection, and sewer cleaning were associated with the highest exposure levels. A significant positive correlation was found between CRP and bacterial exposure (p = 0.013), while significant negative correlations were found between CRP and endotoxin and dust exposures (p = 0.012 and p = 0.018, respectively). No significant associations were found between SAA or CC16 and the exposure measures. Microbial community composition in bioaerosols differed significantly between some work tasks while others showed similar compositions. Viable hazardous microorganisms such as Clostridium perfringens and Aspergillus fumigatus were found in workers' exposures and in respiratory fractions of stationary air samples, indicating potential lung deposition. Further research is needed to assess possible long-term health risks from bioaerosol exposure at WWTPs.

Microbial exposure during recycling of domestic waste: a cross-sectional study of composition and associations with inflammatory markers

OBJECTIVES

This study aims to investigate (1) the microbial community composition by work characteristics and (2) the association between microbial genera level and inflammatory markers among recycling workers.

METHODS

In this cross-sectional study, inhalable dust was collected with personal samplers from 49 production (86 samples) and 10 administrative workers (15 samples). Four groups of micro-organisms were identified down to species-level (aerobic and anaerobic bacteria, and fungi grown at 25°C and 37°C). Inflammatory markers were measured in serum collected at the end of the work shift. Microbial community composition was investigated using redundancy analysis and heatmaps. Associations between the most prevalent microbial genera and inflammatory markers were explored by mixed-effects regression.

RESULTS

Community composition of all groups of micro-organisms except fungi (37°C) differed between production and administrative workers and by type of waste and season among the production workers. Overall, Bacillus, Staphylococcus, Aspergillus and Penicillium were the most prevalent genera. CC16 concentrations increased with Penicillium genus level, C reactive protein and serum amyloid A with Staphylococcus, interleukin 2 (IL-2) and tumour necrosis factor with Bacillus, and IL-8 with Aspergillus. IL-1B decreased with Staphylococcus genus level. Remaining analyses showed no statistically significant associations between microbial genera level and inflammatory markers.

CONCLUSIONS

Recycling workers are exposed to different compositions of microbial species than administrative workers depending on the type of waste handled and season. Specific systemic inflammatory effects were suggested for a limited number of microbial genera that need to be corroborated by future studies.

Analysis of water and aerosol samples of tunnel car washes operated with recycled water for Legionella with culture, qPCR and viability-qPCR

Due to the generation of large quantities of aerosol and the recycling of water, tunnel car washes are discussed as potential sources of legionellosis. Additionally, occupational health and safety aspects are important for tunnel car washes as they are often workplaces. A total of 17 different tunnel car washes were investigated for the presence of Legionella. In the process, 78 water samples and 63 air samples were taken. This comprised samples of municipal and recycled water as well as aerosol from the car wash tunnel and the workplace. The analysis for Legionella included culture method in combination with an immunochromatographic test, qPCR and viability-qPCR. Where possible, Legionella species were identified by sequencing of mip gene. Using the culture method Legionella were detected in 9 of 78 water samples (91 to 10,800 CFU/100 mL). In contrast, quantifiable concentrations of viable Legionella spp. were found in 68 of 78 water samples with viability-qPCR. The median concentration was 9.2 × 105(n = 16) and 7.2 × 105 GU/100 mL (n = 17) for the recycled water from the storage tank and the nozzles in the car wash tunnel. Viable Legionella spp. were detectable in the aerosol at the workplace in 38.1 % of the samples (n = 21). Concentration was between 155 and 3829 GU/m3 (n = 7). L. pneumophila non-serogroup 1 were quantitatively detectable in the recycled water of one car wash, using qPCR methods and culture. Aerosolisation of this species was not detected. The presence of viable Legionella spp. in most water and many aerosol samples as well as the identification of species related to infection suggests that there is a risk of legionellosis through exposure to bioaerosols released from tunnel car washes. Comparison of conventional culture method with qPCR methods showed a considerable underestimation of Legionella concentrations by culture.

Airborne concentrations of bacteria and mold in Korean public-use facilities: measurement, systematic review, meta-analysis, and probabilistic human inhalation risk assessment

Bioaerosols adversely affect human health posing risk to users of public facilities in Korea. Between October 2021 and May 2022, airborne bacteria and mold were measured in 1,243 public-use facilities across 23 categories. A systematic review and meta-analysis were performed on these and other studies from June 2004 to May 2021, and the non-carcinogenic risks to humans were assessed using Monte Carlo simulations. For bacteria, the maximum 95th percentile concentration was 584.4 cfu/m3 and 1384.8 cfu/m3 for mold. The heterogeneity statistic I2 was over 50% in all facilities, and for subway station bacteria, there was a significant difference according to the measurement method. The 95th percentile of hazard by population group was 8.83 × 10-2 to 3.42 × 10-1 for bacteria, and 1.31 × 10-1 to 3.55 × 10-1 for mold. The probability of a hazard quotient exceeding 1 for some population groups was derived from exposure to bacteria and mold in the air resulting from the use of all public facilities. The most powerful explanatory factor for risk was exposure time to the facility, both within (up to 0.922 for bacteria and up to 0.960 for mold) and between populations (up to 0.543 for bacteria and 0.483 for mold). This study identified populations at risk of bioaerosol exposure in Korean public-use facilities and estimated the influencing factors, highlighting the need for comprehensive improvement in bioaerosol control in public-use facilities.

Tracking bioaerosol exposure among municipal solid waste workers using hematological and inflammatory biomarkers

High levels of bioaerosols may exist in the air of municipal solid waste (MSW) management facilities, constituting a significant occupational hazard for workers. In this study, we investigated the potential association between exposure to bioaerosols and inflammatory biomarkers among municipal solid waste workers (MSWWs) at both the landfill site and the municipal solid waste transfer station (MSWTS), in comparison to a control group without exposure. Air sampling was conducted at six points around the landfill, two points at the MSWTS, and one point in a public park (as a control area) during the spring and summer of 2019. The results of our study revealed that airborne pathogens were highly prevalent at the sampling points, especially in the active zone and leachate collection pond. Aspergillus species were the predominant fungal species detected in this study, with the highest occurrence observed for Aspergillus flavus (83.3%), Aspergillus niger, and Aspergillus fumigatus (75.0%). Furthermore, Staphylococcus species accounted for over 75% of the total bacterial bioaerosols detected across all study areas. The blood test results of workers revealed a significant increase in platelets (PLT), immunoglobulin G (IgG), white blood cells (WBC), neutrophils, basophils, and high-sensitivity C-reactive protein (hs-CRP) compared to the control group. Conversely, platelet distribution width (PDW), mean platelet volume (MPV), and platelet-large cell ratio (P-LCR) in the exposed subjects exhibited a decreasing trend compared to the control group. These findings suggest a potential association between exposure to bioaerosols, particularly in the vicinity of open dumpsites, and elevated levels of hematologic and inflammatory markers in circulation. Furthermore, the influence of smoking status and confounding factors appears to be significant in both the control and exposure groups.

Transmission of human-pet antibiotic resistance via aerosols in pet hospitals of Changchun

In recent years, aerosols have been recognized as a prominent medium for the transmission of antibiotic-resistant bacteria and genes. Among these, particles with a particle size of 2 μm (PM2.5) can directly penetrate the alveoli. However, the presence of antibiotic-resistant genes in aerosols from pet hospitals and the potential risks posed by antibiotic-resistant bacteria in these aerosols to humans and animals need to be investigated. In this study, cefotaxime-resistant bacteria were collected from 5 representative pet hospitals in Changchun using a Six-Stage Andersen Cascade Impactor. The distribution of bacteria in each stage was analyzed, and bacteria from stage 5 and 6 were isolated and identified. Minimal inhibitory concentrations of isolates against 12 antimicrobials were determined using broth microdilution method. Quantitative Polymerase Chain Reaction was employed to detect resistance genes and mobile genetic elements that could facilitate resistance spread. The results indicated that ARBs were enriched in stage 5 (1.1-2.1 μm) and stage 3 (3.3-4.7 μm) of the sampler. A total of 159 isolates were collected from stage 5 and 6. Among these isolates, the genera Enterococcus spp. (51%), Staphylococcus spp. (19%), and Bacillus spp. (14%) were the most prevalent. The isolates exhibited the highest resistance to tetracycline and the lowest resistance to cefquinome. Furthermore, 56 (73%) isolates were multidrug-resistant. Quantitative PCR revealed the expression of 165 genes in these isolates, with mobile genetic elements showing the highest expression levels. In conclusion, PM2.5 from pet hospitals harbor a significant number of antibiotic-resistant bacteria and carry mobile genetic elements, posing a potential risk for alveolar infections and the dissemination of antibiotic resistance genes.

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.

The composition of the bacterial communities collected from the PM10 samples inside the Seoul subway and railway station

Health implications of indoor air quality (IAQ) have drawn more attention since the COVID epidemic. There are many different kinds of studies done on how IAQ affects people's well-being. There hasn't been much research that looks at the microbiological composition of the aerosol in subway transit systems. In this work, for the first time, we examined the aerosol bacterial abundance, diversity, and composition in the microbiome of the Seoul subway and train stations using DNA isolated from the PM10 samples from each station (three subway and two KTX stations). The average PM10 mass concentration collected on the respective platform was 41.862 µg/m3, with the highest average value of 45.95 µg/m3 and the lowest of 39.25 µg/m3. The bacterial microbiomes mainly constituted bacterial species of soil and environmental origin (e.g., Acinetobacter, Brevundimonas, Lysinibacillus, Clostridiodes) with fewer from human sources (Flaviflexus, Staphylococcus). This study highlights the relationship between microbiome diversity and PM10 mass concentration contributed by outdoor air and commuters in South Korea's subway and train stations. This study gives insights into the microbiome diversity, the source, and the susceptibility of public transports in disease spreading.

Aeromicrobiology: A global review of the cycling and relationships of bioaerosols with the atmosphere

Airborne microorganisms and biological matter (bioaerosols) play a key role in global biogeochemical cycling, human and crop health trends, and climate patterns. Their presence in the atmosphere is controlled by three main stages: emission, transport, and deposition. Aerial survival rates of bioaerosols are increased through adaptations such as ultra-violet radiation and desiccation resistance or association with particulate matter. Current research into modern concerns such as climate change, global gene transfer, and pathogenicity often neglects to consider atmospheric involvement. This comprehensive review outlines the transpiring of bioaerosols across taxa in the atmosphere, with significant focus on their interactions with environmental elements including abiotic factors (e.g., atmospheric composition, water cycle, and pollution) and events (e.g., dust storms, hurricanes, and wildfires). The aim of this review is to increase understanding and shed light on needed research regarding the interplay between global atmospheric phenomena and the aeromicrobiome. The abundantly documented bacteria and fungi are discussed in context of their cycling and human health impacts. Gaps in knowledge regarding airborne viral community, the challenges and importance of studying their composition, concentrations and survival in the air are addressed, along with understudied plant pathogenic oomycetes, and archaea cycling. Key methodologies in sampling, collection, and processing are described to provide an up-to-date picture of ameliorations in the field. We propose optimization to microbiological methods, commonly used in soil and water analysis, that adjust them to the context of aerobiology, along with other directions towards novel and necessary advancements. This review offers new perspectives into aeromicrobiology and calls for advancements in global-scale bioremediation, insights into ecology, climate change impacts, and pathogenicity transmittance.

Editorial for Special Issue: "Airborne Microbes and Their Potential Influence"

Airborne microbes, comprising a diverse range of bacteria and fungi, are a pervasive component of the atmosphere, with concentrations typically ranging from 102 to 107 cells per cubic meter [...].

Dynamic human exposure to airborne bacteria-associated antibiotic resistomes revealed by longitudinal personal monitoring data

Airborne antibiotic-resistant bacteria (ARB) can critically impact human health. We performed resistome profiling of 283 personal airborne exposure samples from 15 participants spanning 890 days and 66 locations. We found a greater diversity and abundance of airborne bacteria community and antibiotic resistomes in spring than in winter, and temperature contributed largely to the difference. A total of 1123 bacterial genera were detected, with 16 genera dominating. Of which, 7/16 were annotated as major antibiotic resistance gene (ARG) hosts. The participants were exposed to a highly dynamic collection of ARGs, including 322 subtypes conferring resistance to 18 antibiotic classes dominated by multidrug, macrolide-lincosamide-streptogramin, β-lactam, and fosfomycin. Unlike the overall community-level bacteria exposure, an extremely high abundance of specific ARG subtypes, including lunA and qacG, were found in some samples. Staphylococcus was the predominant genus in the bacterial community, serving as a primary bacterial host for the ARGs. The annotation of ARG-carrying contigs indicated that humans and companion animals were major reservoirs for ARG-carrying Staphylococcus. This study contextualized airborne antibiotic resistomes in the precision medicine framework through longitudinal personal monitoring, which can have broad implications for human health.

The Presence of Legionella in Water Used for Car Washing: Implications for Public Health

Although today all of the aspects of Legionella are better understood than in the past, in many countries the interest is still mainly focused on healthcare and tourism facilities. Other at-risk areas are less explored, such as those where workers are often in contact with water during their activities. In reality, any water system capable of producing aerosols can be considered a potential source of Legionella transmission, including car washes, where a large number of users work and flow through annually. From January to May 2022, 120 samples were carried out in 30 car washes located in Messina (Italy): 60 samples of water and 60 of aerosols. The aim of this investigation was to evaluate the risk of legionellosis in car washing workers exposed to potentially contaminated aerosols. To increase the probability of finding Legionella, the sample collections were organized on different days of the week. Of the total samples taken, 10 (8.3%) were positive for Legionella: seven (11.7%) water (range 100-1000 CFU) and three (5%) aerosol (range 10-150 CFU) samples. Detected serogroups were L. pneumophila sgr 1, 7, 10 and Legionella gormanii. Given the results obtained, preventative measures should be implemented in such facilities in order to protect the health of users and car wash operators.

Bioaerosol dispersion and environmental risk simulation: Method and a case study for a biopharmaceutical plant of Gansu province, China

Pathogenic bacteria pose a great threat to global public health from environmental and public health perspectives, especially regarding the impact of the COVID-19 pandemic worldwide. As a result, the increased risk of pathogenic bioaerosol exposure imposes a considerable health burden and raises specific concerns about the layout and location of vaccine manufacturers. This study proposed a grid computing method based on the CALPUFF modelling system and population-based environmental risks to reduce bioaerosol-related potential risks. We previously used the CALPUFF model to quantify the diffusion level, the spatial distribution of emissions, and potential environmental risks of bioaerosol leakage in Gansu province's Zhongmu Lanzhou biopharmaceutical plant from July 24, 2019, to August 20, 2019. By combining it with publicly available test data, the credibility was confirmed. Based on our previous research, the CALPUFF model application combined with the environmental population-based environmental risks in two scenarios: the layout and site selection, was explored by using the leakage accident of Zhongmu Lanzhou biopharmaceutical plant of Gansu province as a case study. Our results showed that the site selection method of scenario 2 coupled with the buffer area was more reasonable than scenario 1, and the final layout site selection point of scenario 2 was grid 157 as the optimal layout point. The simulation results demonstrated agreement with the actual survey. Our findings could assist global bioaerosol manufacturers in developing appropriate layout and site selection strategies to reduce bioaerosol-related potential environmental risks.

Intensive poultry farming: A review of the impact on the environment and human health

Poultry farming is one of the most efficient animal husbandry methods and it provides nutritional security to a significant number of the world population. Using modern intensive farming techniques, global production has reached 133.4 mil. t in 2020, with a steady growth each year. Such intensive growth methods however lead to a significant environmental footprint. Waste materials such as poultry litter and manure can pose a serious threat to environmental and human health, and need to be managed properly. Poultry production and waste by-products are linked to NH₃, N₂O and CH₄ emissions, and have an impact on global greenhouse gas emissions, as well as animal and human health. Litter and manure can contain pesticide residues, microorganisms, pathogens, pharmaceuticals (antibiotics), hormones, metals, macronutrients (at improper ratios) and other pollutants which can lead to air, soil and water contamination as well as formation of antimicrobial/multidrug resistant strains of pathogens. Dust emitted from intensive poultry production operations contains feather and skin fragments, faeces, feed particles, microorganisms and other pollutants, which can adversely impact poultry health as well as the health of farm workers and nearby inhabitants. Fastidious odours are another problem that can have an adverse impact on health and quality of life of workers and surrounding population. This study discusses the current knowledge on the impact of intensive poultry farming on environmental and human health, as well as taking a look at solutions for a sustainable future.

Safe use of PHI6 IN the experimental studies

Surrogate viruses theoretically provide an opportunity to study the viral spread in an indoor environment, a highly needed understanding during the pandemic, in a safe manner to humans and the environment. However, the safety of surrogate viruses for humans as an aerosol at high concentrations has not been established. In this study, Phi6 surrogate was aerosolized at high concentration (Particulate matter_2.5: ∼1018 μg m^-3) in the studied indoor space. Participants were closely followed for any symptoms. We measured the bacterial endotoxin concentration of the virus solution used for aerosolization as well as the concentration in the room air containing the aerosolized viruses. In addition, we measured how the bacterial endotoxin concentration of the sample was affected by different traditional virus purification procedures. Despite the purification, bacterial endotoxin concentration of the Phi6 was high (350 EU/ml in solution used for aerosols) with both (two) purification protocols. Bacterial endotoxins were also detected in aerosolized form, but below the occupational exposure limit of 90 EU/m³. Despite these concerns, no symptoms were observed in exposed humans when they were using personal protective equipment. In the future, purification protocols should be developed to reduce associated bacterial endotoxin levels in enveloped bacterial virus specimens to ensure even safer research use of surrogate viruses.

Quantitative microbial risk assessment with nasal/oral breathing pattern for S. aureus bioaerosol emission from aeration tanks and residual sludge storage yard in a wastewater treatment plant

A large number of pathogenic bioaerosols are generated during the treatment process of wastewater treatment plants (WWTPs), and they can pose potential risks to human health. Therefore, this study systematically analyzed the emission characteristics of Staphylococcus aureus bioaerosols released from an inverted umbrella aeration tank, a microporous aeration tank, and a residual sludge storage yard in a WWTP, and quantitatively evaluated the health risks of four kinds of exposed populations with nasal/oral breathing patterns under optimistic and conservative estimations. The results displayed that the bioaerosol concentration in inverted umbrella aeration tank was higher than that in microporous aeration tank and residual sludge storage yard. Aerosolization ratio in residual sludge storage yard was an order of magnitude lower than that in aeration tanks. Sludge workers were at higher health risks than the other three exposed populations. The health risks of nasal breathers (infection risk: 1.62 × 10^-5-2.56 × 10^-3 pppy; disease burden: 4.24 × 10^-8-6.72 × 10^-6 DALYs pppy) were 0.61-0.63 times higher than those of oral breathers (infection risk: 9.95 × 10^-6-1.59 × 10^-3 pppy; disease burden: 2.61 × 10^-8-4.18 × 10^-6 DALYs pppy). For female field engineers using oral breathing, laboratory technicians, and researchers without personal protective equipment (PPE), infection risk and disease burden had the opposite results, which indicated that satisfying one certain benchmark did not mean absolute safety. In addition, health risks of exposed populations were reduced by an order of magnitude after wearing PPE. This study can provide a reliable theoretical basis for the risk prevention of bioaerosols and supply data support for the strategies of health risk control perspectives for local sewage utilities.

Assessing the health risk of living near composting facilities on lung health, fungal and bacterial disease in cystic fibrosis: a UK CF Registry study

AIM

To explore the health risk of living near permitted composting sites (PCSs) on disease severity in children and adults with cystic fibrosis (CF) across the UK.  METHODS: A semi-individual cross-sectional study was used to examine the risk of disease severity in people with CF (pwCF) within and beyond 4 km of PCSs in the UK in 2016. All pwCF registered in the UK CF Registry were eligible for this study. Linear and Poisson regressions, adjusted for age, gender, genotype, BMI, Pseudomonas aeruginosa and deprivation, were used to quantify associations between distance to a PCS and percent predicted forced expiratory volume in one second (ppFEV₁), pulmonary exacerbations (#IVdays), and fungal and bacterial infections.

RESULTS

The mean age of the 9,361 pwCF (3,931 children and 5,430 adults) studied was 20.1 (SD = 14.1) years; 53.3% were male; and 49.2% were homozygous F508del. Over 10% of pwCF (n = 1,015) lived within 4 km of a PCS. We found no statistically significant difference in ppFEV₁ and #IVdays/year in children. However, in adults, ppFEV₁ was -1.07% lower (95% confidence interval (CI): -2.29%, 0.16%) and #IVdays/year were 1.02 day higher (95%CI: 1.01, 1.04) within 4 km of a PCS. Furthermore, there were statistically significant differences in mean ppFEV₁ in CF adults with Aspergillus fumigatus (58.2.% vs 62.0%, p = 0.005) and Candida spp. (56.9% vs 59.9%, p = 0.029) residing within 4 km of a PCS. No associations were identified for allergic bronchopulmonary aspergillosis, P. aeruginosa or Staphylococcus aureus.

CONCLUSIONS

This novel national study provides evidence that adults with CF living near a PCS may experience small reductions in lung function, an increased risk of pulmonary exacerbations, and more frequent fungal infections. If confirmed by studies using refined exposure assessment methods accounting for bioaerosol dispersion, these results could have important implications for the living environment of pwCF.

Kinetics and mechanism analysis on self-decay of airborne bacteria:biological and physical decay under different temperature

Bioaerosol as an important medium has aroused widespread concern on its potential hazards in disease transmission and environment biosafety. However, little is known about the duration and self-decay of airborne bacteria in the atmosphere environment. Further, the self-decay process is proposed to include biological-decay and physical-decay. At present, there are many reports on the bacteria apoptosis mechanism and airborne particle migration. However, few studies focus on self-decay during the physical movement of airborne bacteria. The present study investigated self-decay laws and efficiencies of airborne bacteria in the sealed reactor under room temperature (18 ± 2 °C, RT) and low temperature (3 ± 2 °C, LT). The self-decay rate constants of 0.0089, 0.0133, 0.0092, and 0.0122 min^-1 were obtained under RT-E. coli, LT-E. coli, RT-S. aureus and LT-S. aureus, respectively. There was no significant difference between the self-decay efficiency of gram-negative and gram-positive bacteria under the same conditions. Nevertheless, gram-negative bacteria were more sensitive to temperature change compared with gram-positive bacteria, where the self-decay efficiency of gram-negative under LT was 49% higher than that under RT, and the value of gram-positive was 32% at the same condition. Furthermore, the laws of biological-decay and physical-decay conformed to the first-order kinetic model by theoretical derivation. Biological-decay accounted for 59.5% at RT and 88.5% at LT among self-decay, which is mainly caused by energy absorption, environmental stress, and bacterial structure changes. Physical-decay mainly caused by gravity settlement accounting for 40% at RT and 10% at LT among self-decay, approximately. Meanwhile, the influence of environmental factors on self-decay was mainly reflected in the biological-decay process. Overall, it is of great significance for clarifying the changing laws of bioaerosol and controlling the transmission of airborne bacteria.

Global Meta-analysis of Airborne Bacterial Communities and Associations with Anthropogenic Activities

Airborne microbiome alterations, an emerging global health concern, have been linked to anthropogenic activities in numerous studies. However, these studies have not reached a consensus. To reveal general trends, we conducted a meta-analysis using 3226 air samples from 42 studies, including 29 samples of our own. We found that samples in anthropogenic activity-related categories showed increased microbial diversity, increased relative abundance of pathogens, increased co-occurrence network complexity, and decreased positive edge proportions in the network compared with the natural environment category. Most of the above conclusions were confirmed using the samples we collected in a particular period with restricted anthropogenic activities. Additionally, unlike most previous studies, we used 15 human-production process factors to quantitatively describe anthropogenic activities. We found that microbial richness was positively correlated with fine particulate matter concentration, NH₃ emissions, and agricultural land proportion and negatively correlated with the gross domestic product per capita. Airborne pathogens showed preferences for different factors, indicating potential health implications. SourceTracker analysis showed that the human body surface was a more likely source of airborne pathogens than other environments. Our results advance the understanding of relationships between anthropogenic activities and airborne bacteria and highlight the role of airborne pathogens in public health.

Seasonal variation of quantitative microbial risk assessment for three airborne enteric bacteria from wastewater treatment plant emissions

Airborne E. coli, fecal coliform, and Enterococcus are all related to sewage worker's syndrome and therefore used as target enteric bioaerosols about researches in wastewater treatment plants (WWTPs). However, most of the studies are often inadequately carried out because they lack systematic studies reports bioaerosols emission characteristics and health risk assessments for these three enteric bacteria during seasonal variation. Therefore, quantitative microbial risk assessment based on Monte Carlo simulation was utilized in this research to assess the seasonal variations of health risks of the three enteric bioaerosols among exposure populations (academic visitors, field engineers, and office staffs) in a WWTP equipped with rotating-disc and microporous aeration modes. The results show that the concentrations of the three airborne bacteria from the rotating-disc aeration mode were 2-7 times higher than the microporous aeration mode. Field engineers had health risks 1.5 times higher than academic visitors due to higher exposure frequency. Health risks of airborne Enterococcus in summer were up to 3 times higher than those in spring and winter. Similarly, health risks associated to E. coli aerosol exposure were 0.3 times higher in summer compared to spring. In contrast, health risks associated with fecal coliform aerosol were between 2 and 19 times lower in summer compared to spring and winter seasons. Data further suggest that wearing of N95 mask could minimize health risks by 1-2 orders of magnitude. This research shed light on seasonal variation of health risks associated with bioaerosol emission from wastewater utilities.

Safety Level of Microorganism-Bearing Products Applied in Soil-Plant Systems

The indiscriminate use of chemical fertilizers adversely affects ecological health and soil microbiota provoking loss of soil fertility and greater pathogen and pest presence in soil-plant systems, which further reduce the quality of food and human health. Therefore, the sustainability, circular economy, environmental safety of agricultural production, and health concerns made possible the practical realization of eco-friendly biotechnological approaches like organic matter amendments, biofertilizers, biopesticides, and reuse of agro-industrial wastes by applying novel and traditional methods and processes. However, the advancement in the field of Biotechnology/Agriculture is related to the safety of these microorganism-bearing products. While the existing regulations in this field are well-known and are applied in the preparation and application of waste organic matter and microbial inoculants, more attention should be paid to gene transfer, antibiotic resistance, contamination of the workers and environment in farms and biotech-plants, and microbiome changes. These risks should be carefully assessed, and new analytical tools and regulations should be applied to ensure safe and high-quality food and a healthy environment for people working in the field of bio-based soil amendments.

MRSA Colonization in Workers from Different Occupational Environments—A One Health Approach Perspective

Staphylococcus aureus and particularly methicillin-resistant S. aureus (MRSA) infections are currently associated with extremely high morbidity and mortality rates worldwide. The global escalation in the development of antibiotic-resistant human pathogens and S. aureus ability in developing new clones with the capacity to invade community settings, leads to an urgent need to develop accurate and efficient assessments of S. aureus colonization in occupational settings, particularly those with increased risk of human and animal colonization and food contamination. Here we present cross-sectional studies with the aim to assemble crucial information regarding MRSA prevalence in workers from five different Portuguese occupational environments (bakeries, swineries (humans and animals), ambulance crews, veterinary clinics and healthcare facilities). Our data demonstrated high prevalence of S. aureus asymptomatic carriers among bakery workers (40%; 75% MSSA and 25% MRSA), swinery workers (54%; 8% MSSA and 46% MRSA), firefighters (48.5%; 24% MSSA and 21% MRSA) and healthcare workers (Study 1: 42.2%; 18.4% MSSA and 23.7% MRSA, Study 2: 43.3% MRSA). S. aureus prevalence in veterinary staff was 7.1% (MSSA), lower than the results obtained in control groups (33.3% S. aureus; MRSA 4% to 10%). The present study sustains the urge to develop accurate and efficient assessment of S. aureus human and animal colonization, particularly in high risk occupational settings, with proper guidelines and validated procedures in order to avoid potential hazardous health outcomes associated with bioaerosol exposure and associated infectious diseases.

Long-Term Studies of Biological Components of Atmospheric Aerosol: Trends and Variability

Background: Biological components of atmospheric aerosol affect the quality of atmospheric air. Long-term trends in changes of the concentrations of total protein (a universal marker of the biogenic component of atmospheric aerosol) and culturable microorganisms in the air are studied. Methods: Atmospheric air samples are taken at two locations in the south of Western Siberia and during airborne sounding of the atmosphere. Sample analysis is carried out in the laboratory using standard culture methods (culturable microorganisms) and the fluorescence method (total protein). Results: Negative trends in the average annual concentration of total protein and culturable microorganisms in the air are revealed over more than 20 years of observations. For the concentration of total protein and culturable microorganisms in the air, intra-annual dynamics is revealed. The ratio of the maximum and minimum values of these concentrations reaches an order of magnitude. The variability of concentrations does not exceed, as a rule, two times for total protein and three times for culturable microorganisms. At the same time, for the data obtained in the course of airborne sounding of the atmosphere, a high temporal stability of the vertical profiles of the studied concentrations was found. The detected biodiversity of culturable microorganisms in atmospheric air samples demonstrates a very high variability at all observation sites. Conclusions: The revealed long-term changes in the biological components of atmospheric aerosol result in a decrease in their contribution to the atmospheric air quality index.

Environmental Factors and the Risk of Developing Type 1 Diabetes-Old Disease and New Data

Simple Summary

Despite many studies, the risk factors of type 1 diabetes (T1DM) in children and adolescents are still not fully understood and remain a big challenge. Therefore, an extensive online search for scientific research on factors related to diabetes has been performed for the identification of new factors of unexplained etiology. A better understanding of the role of viral, bacterial, and yeast-like fungi infections related to the risk of T1DM in children and adolescents and the identification of new risk factors, especially those spread by the droplet route, is of great importance for people and families with diabetes.

Abstract

The incidence of type 1 diabetes (T1D) is increasing worldwide. The onset of T1D usually occurs in childhood and is caused by the selective destruction of insulin-producing pancreatic islet cells (β-cells) by autoreactive T cells, leading to insulin deficiency. Despite advanced research and enormous progress in medicine, the causes of T1D are still not fully understood. Therefore, an extensive online search for scientific research on environmental factors associated with diabetes and the identification of new factors of unexplained etiology has been carried out using the PubMed, Cochrane, and Embase databases. The search results were limited to the past 11 years of research and discovered 143 manuscripts published between 2011 and 2022. Additionally, 21 manuscripts from between 2000 and 2010 and 3 manuscripts from 1974 to 2000 were referenced for historical reference as the first studies showcasing a certain phenomenon or mechanism. More and more scientists are inclined to believe that environmental factors are responsible for the increased incidence of diabetes. Research results show that higher T1D incidence is associated with vitamin D deficiency, a colder climate, and pollution of the environment, as well as the influence of viral, bacterial, and yeast-like fungi infections. The key viral infections affecting the risk of developing T1DM are rubella virus, mumps virus, Coxsackie virus, cytomegalovirus, and enterovirus. Since 2020, i.e., from the beginning of the COVID-19 pandemic, more and more studies have been looking for a link between Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and diabetes development. A better understanding of the role of viral, bacterial, and yeast-like fungi infections related to the risk of T1DM in children and adolescents and the identification of new risk factors, especially those spread by the droplet route, is of great importance for people and families with diabetes.

Drug Resistance and Epigenetic Modulatory Potential of Epigallocatechin-3-Gallate Against Staphylococcus aureus

Antimicrobial resistance of human pathogens, such as methicillin-resistant Staphylococcus aureus, is described by the World Health Organization as a health global challenge and efforts must be made for the discovery of new effective and safe compounds. This work aims to evaluate epigallocatechin-3-gallate (EGCG) epigenetic and modulatory drug potential against S. aureus in vitro and in vivo. S. aureus strains were isolated from commensal flora of healthy volunteers. Antibiotic susceptibility and synergistic assay were assessed through disk diffusion accordingly to EUCAST guidelines with and without co-exposure to EGCG at final concentrations of 250 µg/ml, 100 µg/ml, 50 µg/ml, and 25 µg/ml. Transcriptional expression of orfx, spdC, and WalKR was performed through qRT-PCR. A 90-day interventional study was performed with daily consumption of 225 mg of EGCG. Obtained data revealed a high prevalence of S. aureus colonization in healthcare workers and clearly demonstrated the antimicrobial and synergistic potential of EGCG as well as divergent resistant phenotypes associated with altered transcriptional expression of epigenetic and drug response modulators genes. Here, we demonstrate the potential of EGCG for antimicrobial treatment and/or therapeutic adjuvant against antibiotic-resistant microorganisms and report divergent patterns of epigenetic modulators expression associated with phenotypic resistance profiles.

Multiplexed Workplace Measurements in Biogas Plants Reveal Compositional Changes in Aerosol Properties

Anaerobic digestion is an emerging technology producing energy from renewable resources or food waste. Exposure screenings, comprising hazardous substances and biological agents, at different workplaces are necessary for a comprehensive overview of potential hazards in order to assess the risk of employees in biogas plants. In order to analyse these parameters, workplace measurements were conducted in seven full-scale anaerobic digesters. Personal and stationary sampling was performed for inhalable and respirable particles, volatile organic compounds, ammonia, hydrogen sulphide, carbon monoxide, and carbon dioxide. Furthermore, concentrations of the total cell count, endotoxins, and fungi-down to species level-were determined in comparison to windward air. Sequencing of the 16S rRNA genes was utilized for the determination of the bacterial composition inside the biogas plants. Measurements of hazardous substances show hardly values reaching the specific occupational exposure limit value, except ammonia. An approximate 5-fold increase in the median of the total cell count, 15-fold in endotoxins, and 4-fold in fungi was monitored in the biogas plants compared with windward air. Specifying the comparison to selected workplaces showed the highest concentrations of these parameters for workplaces related to delivery and cleaning. Strikingly, the fungal composition drastically changed between windward air and burdened workplaces with an increase of Aspergillus species up to 250-fold and Penicillium species up to 400-fold. Sequence analyses of 16S rRNA genes revealed that many workplaces are dominated by the order of Bacillales or Lactobacillales, but many sequences were not assignable to known bacteria. Although significant changes inside the biogas plant compared with windward air were identified, that increase does not suggest stricter occupational safety measures at least when applying German policies. However, exposure to biological agents revealed wide ranges and specific workplace measurements should be conducted for risk assessment.

The emergency discharge of sewage to the Bay of Gdańsk as a source of bacterial enrichment in coastal air

The purpose of this research was to study the presence of potential pathogenic bacteria in the seawater and air in five coastal towns (Hel, Puck, Gdynia, Sopot, Gdańsk-Brzeźno) as well as the enrichment of bacteria from the seawater into the coastal air after an emergency discharge of sewage into the Bay of Gdańsk. A total of 594 samples of air and seawater were collected in the coastal zone between spring and summer (between 2014 and 2018). Air samples were collected using the impact method with a SAS Super ISO 100. The multivariate analysis, conducted using contingency tables, showed a statistically significant variation between the concentration of coliforms, psychrophilic and mesophilic bacteria in the seawater microlayer and air in 2018, after an emergency discharge of sewage into the Bay of Gdańsk, compared to 2014-2017. Moreover, we detected a marine aerosol enrichment in psychrophilic, mesophilic bacteria, coliforms and Escherichia coli. We also showed a statistically significant relationship between the total concentration of bacteria and humidity, air temperature, speed and wind direction. This increased concentration of bacteria in the seawater and coastal air, and the high factor of air enrichment with bacteria maybe associated with the emergency discharge of wastewater into the Bay of Gdańsk. Therefore, it is suggested that in the event of a malfunction of a sewage treatment plant, as well as after floods or sudden rainfall, the public should be informed about the sanitary and epidemiological status of the coastal waters and be recommended to limit their use of coastal leisure areas.

Staphylococci and fecal bacteria as bioaerosol components in animal housing facilities in the Zoological Garden in Chorzów

Zoos are places open for a large number of visitors, adults and children, who can admire exotic as well as indigenous animal species. The premises for animals may contain pathogenic microbes, including those exhibiting antibiotic resistance. It poses a threat to people remaining within the zoo premises, both for animal keepers who meet animals on a daily basis and visitors who infrequently have contact with animals. There are almost no studies concerning the presence on the concentration of airborne bacteria, especially staphylococci and fecal bacteria in animal shelters in the zoo. There is no data about antibiotic resistance of staphylococci in these places. The results will enable to determine the scale of the threat that indicator bacteria from the bioaerosol pose to human health within zoo premises. This study conducted in rooms for 5 animals group (giraffes, camels, elephants, kangaroos, and Colobinae (species of monkey)) in the Silesian Zoological Garden in Chorzów (Poland). The bioaerosol samples were collected using a six-stage Andersen cascade impactor to assess the concentrations and size distribution of airborne bacteria. Staphylococci were isolated from bioaerosol and tested for antibiotic resistance. In our study, the highest contamination of staphylococci and fecal bacteria was recorded in rooms for camels and elephants, and the lowest in rooms for Colobinae. At least 2/3 of bacteria in bioaerosol constituted respirable fraction that migrates into the lower respiratory tract of the people. In investigated animal rooms, the greatest bacteria contribution was recorded for bioaerosol fraction sized 1.1-3.3μm. Bacterial concentrations were particularly strong in spring and autumn, what is related to shedding fur by animals. Among the isolated staphylococci which most often occurred were Staphylococcus succinus, S. sciuri, and S. vitulinus. The highest antibiotic resistance was noted in the case of Staphylococcus epidermidis, while the lowest for S. xylosus. In addition to standard cleaning of animal rooms, periodic disinfection should be considered. Cleaning should be carried out wet, which should reduce dust, and thus the concentrations of bacteria in the air of animal enclosures.

Proliferation of antibiotic-resistant microorganisms and associated genes during composting: An overview of the potential impacts on public health, management and future

Antibiotic residues together with non-antibiotic drugs and heavy metals act as a selective pressure for the spread of antibiotic-resistant microorganisms (ARMs), antibiotic-resistant genes (ARGs), and mobile genetic elements (MGEs) during composting of livestock manure. ARMs, ARGs and MGEs have become emerging contaminants since they are regularly implicated in the majority of compost produced from livestock manure. The prevalence of these contaminants in agricultural soil receiving compost has drawn huge attention globally due to the risks they pose to the total environment. Although a large body of literature exists on the application of composting methods in minimizing the relative abundance of these contaminants, there is a paucity of information on the robustness, limitations and opportunities and threats of various composting protocols currently deployed. To address this knowledge gap, the current review compiled literature on the origin and mechanisms of the proliferation of ARMs, ARGs, and MGEs during composting of livestock manure. The effectiveness of current composting protocols in the reduction or removal of emerging contaminants was evaluated. Furthermore, the potential environmental impacts and human health risks of these contaminants following land application of compost were also presented. Finally, we propose some strategic approaches for the reduction of ARGs and MGEs during composting of livestock manure.

Application of impedance measurement to investigate in vitro inhalation toxicity of bacteria

BACKGROUND

Workers of agriculture and intensive life stock farming are exposed to highly contaminated workplaces. Bioaerosol exposures are suspected to trigger respiratory health effects of the workers. So far, risk evaluation of bioaerosols has been assessed through the infectivity of comprising biological agents that is classified in Europe by four risk groups according to the criteria of Directive 2000/54EC of the European Parliament. However, this directive additionally requires the risk assessment of allergenic and toxigenic effects without further elaboration. The aim of our study was to establish an in vitro screening system that is able to measure inhalative toxic effects of bacteria and their metabolites.

METHODS

In this study, we analyzed three bacterial toxins and five culture supernatants of selected bacteria with known toxicity as model agents exposed to the lung epithelial cell line NuLi-1. We used electrical cell-substrate impedance sensing (ECIS) method to monitor real-time cell changes and the viability test Prestoblue™.

RESULTS

We confirmed concentration dependent cytotoxic effects of the selected toxins in NuLi-1 cells over a period of up to 48 h. Each toxin resulted in a different but specific impedance profile over time according to their mode of action, whereas viability assay showed the metabolic activity of the cells at a chosen time point without revealing any information on their mode of action. Furthermore, dose-response-relationships were monitored. Tested model bacteria (Streptoccous pneumoniae, Acinetobacter radioresistens, Aerococcus viridans, Aeromonas hydrophila) reacted according to their expected toxicity except one bacterium (Enterococcus faecalis). The established assays revealed the concentration dependent onset and intensity of bacterial cytotoxicity and the viability of the cells at 24 h and 48 h exposure.

CONCLUSION

Impedance measurement and the viability assay Prestoblue™ in combination are suitable as sensitive screening methods to analyze toxic potential of bacteria and can therefor support the risk assessment of workplaces in terms of the directive 2000/54/EC.

Production of composted recycled manure solids from a Canadian dairy farm: Impact on microbial air quality in experimental conditions

Recycled manure solids (RMS) produced in dairy farms from fresh manure need to be sanitized before using them as bedding material. However, the impact on air quality of composting RMS remains unknown. Four RMS composting methods were tested during a 10-day aging of piles in experimental chambers: static windrow (SW), turned windrow (TW), SW following drum composting for 24 h (DC24) or SW following drum composting for 72 h (DC72). Air samples were collected using a SASS®3100 Dry Air Sampler on days 0 (pilling of the RMS), 5, and 10. Bacteria (16S rRNA genes), Penicillium/Aspergillus, A fumigatus, and 11 human pathogenic bacteria (e.g. Klebsiella pneumonia) were quantified by qPCR while endotoxins and dust particles were, respectively, measured by LAL assays and with a DustTrak^TM DRX Aerosol Monitor. On day 0, RMS produced by SW and TW yielded the lowest concentrations of airborne bacteria, while DC24 resulted in the lowest levels of Penicillium/Aspergillus and dust particles. SW method led on day 5 to the lowest concentration of bacteria and Penicillium/Aspergillus, and DC24 and DC72 to the lowest concentration of airborne dust. On day 10, SW and TW piles were associated with the lowest levels of Penicillium/Aspergillus and dust particles. A significant difference was observed between concentration of airborne bacteria, Penicillium/Aspergillus and endotoxins before and during the turnover of TW piles. None of the studied human pathogens was detected in the air samples. Results of the present study suggest that SW and TW are the most promising methods for the production of composted RMS with respect to microbial air quality. However, the experimental chambers do not accurately represent commercial dairy barns and further research on these composting methods is necessary. Finally, the study highlights that bedding material and its management may be determinant factors for air quality in dairy barns.Implications: The research evaluated the impact on microbial air quality of composting recycled manure solids (RMS) produced from fresh cow manure. RMS need to be composted or sanitized before using them as bedding material for animals. The impact on animal health of RMS still needs to be confirmed, while the effect on air quality and the health of dairy farmers is unknown. In the present study, microbial air quality associated with four RMS composting methods was investigated. Data revealed that two methods resulted in lower aerosolization of dust particles, endotoxins, molds, and bacteria.

Mold and Yeast-Like Fungi in the Seaside Air of the Gulf of Gdańsk (Southern Baltic) after an Emergency Disposal of Raw Sewage

The aim of this study was to determine the correlation between the meteorological factors and the number of molds and yeast-like fungi in the air in the five coastal towns in the years 2014-2017, and in 2018, after emergency disposal of raw sewage to the Gdańsk Gulf. In the years 2014-2018, a total number of 88 air samples were collected in duplicate in the five coastal towns of Hel, Puck, Gdynia, Sopot, and Gdańsk-Brzeźno. After the application of the (PCA) analysis, this demonstrated that the first principal component (PC1) had a positive correlation with the water temperature, wind speed, air temperature, and relative humidity. The second principal component (PC2) had a positive correlation with the relative humidity, wind speed, wind direction, and air temperature. In 2018, potentially pathogenic mold and yeast-like fungi (Candida albicans, Stachybotrys chartarum complex, Aspergillus section Fumigati) were detected in the seaside air. While the detected species were not observed in the years 2014-2017. We suggest that it is advisable to inform residents about the potential health risk in the event of raw sewage disposal into the water. Moreover, in wastewater treatment plants, tighter measures, including wastewater disinfection, should be introduced.

Pollen and Fungal Spores Evaluation in Relation to Occupants and Microclimate in Indoor Workplaces

Indoor air quality depends on many internal or external factors mutually interacting in a dynamic and complex system, which also includes indoor workplaces, where subjects are exposed to many pollutants, including biocontaminants such as pollen and fungal spores. In this context, the occupants interact actively with their environment through actions, modifying indoor environmental conditions to achieve their own thermal comfort. Actions such as opening/closing doors and windows and turning on/off air conditioning could have effects on workers’ health. The present study explored the contribution of human occupants to pollen and fungal spore levels in indoor workplaces, combining aerobiological, microclimate, and worker monitoring during summer and winter campaigns. We evaluated the overall time spent by the workers in the office, the workers’ actions regarding non-working days and working days, and non-working hours and working hours, during two campaigns of pollen and fungal spore monitoring. Our results showed that the biocontaminant values depend on many mutually interacting factors; hence, the role of all of the factors involved should be investigated. In this regard, aerobiological monitoring should be a valid tool for the management of occupational allergies, providing additional information to improve occupational health protection strategies.

Development of a size-selective sampler combined with an adenosine triphosphate bioluminescence assay for the rapid measurement of bioaerosols

In this study, a size-selective bioaerosol sampler was built and combined with adenosine triphosphate (ATP) bioluminescence assay for measuring the bioaerosol concentration more rapidly and easily. The ATP bioaerosol sampler consisted of a respirable cyclone, an impactor to collect bioaerosols onto the head of a swab used for ATP bioluminescence assay, a swab holder, and a sampling pump. The collection efficiency of the impactor was tested using aerosolized sodium chloride particles and then the particle diameter corresponding to the collection efficiency of 50% (cut-off diameter) was evaluated. The experimental cut-off diameter was 0.44 μm. The correlations between ATP bioluminescence (relative light unit; RLU) from commercially available swabs (UltraSnap and SuperSnap, Hygiena, LLC, U.S.A.) and colony forming unit (CFU) were examined using Escherichia coli (E. coli) suspension and then the conversion equations from RLU to CFU were obtained. From the correlation results, the R² values of UltraSnap and SuperSnap were 0.53 and 0.81, respectively. The conversion equations were the linear function and the slopes of UltraSnap and SuperSnap were 633.6 and 277.78, respectively. In the lab and field tests, the ATP bioaerosol sampler and a conventional Andersen impactor were tested and the results were compared. In the lab tests, concentrations of aerosolized E. coli collected using the sampler were highly correlated to those from the Anderson impactor (R² = 0.85). In the field tests, the concentrations measured using the ATP bioaerosol sampler were higher than those from the Andersen impactor due to the limitations of the colony counting method. These findings confirm the feasibility of developing a sampler for rapid measurement of bioaerosol concentrations, offering a compact device for measuring exposure to bioaerosols, and an easy-to-use methodological concept for efficient air quality management.

A cohort study of cucumber greenhouse workers' exposure to microorganisms as measured using NGS and MALDI-TOF MS and biomarkers of systemic inflammation

Work in greenhouses entails exposure to airborne fungi and bacteria. The aims of this study are to obtain knowledge about whether exposure to fungal and bacterial genera and species during work in a cucumber greenhouse is affected by work tasks, and whether a cohort of greenhouse workers' serum levels of serum amyloid A (SAA) and C-reactive protein (CRP), biomarkers of systemic inflammation, are associated with this. Data on personal exposure to airborne fungal and bacterial species measured over 4 years as well as serum levels of SAA and CRP sampled over two years were analyzed. For data analysis, the main work tasks were grouped into three different groups, called 'grouped work task'. Microorganisms were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) and next-generation sequencing (NGS). The 'daily exposure' of greenhouse workers' were as follows: 4.8 × 10⁴ CFU bacteria/m³, 1.4 × 10⁶ CFU fungi/m³, and 392 EU/m³ of endotoxin. Workers were exposed to many different microbial species including several species within the genera Acinetobacter, Bacillus, Microbacterium, Pseudomonas, Staphylococcus, and Streptomyces. The genera Ralstonia and Cladosporium were found in most samples. The exposure levels as well as the microbial composition were associated significantly with grouped work task and season with high exposures during tasks in close contact with mature and old plants and in the autumn. CRP and SAA levels were also associated with exposure level and grouped work tasks. The Shannon-Wiener indices were not different in the 3 'grouped work tasks'. Several specific species including e.g. Halomonas elongata, Stenotrophomonas maltophilia, Podosphaera fusca, and Wallemia spp. were found frequently or in high concentrations in the exposures associated with the highest levels of CRP and SAA. The microorganisms S. maltophilia, P. fusca, and Wallemia spp. were also found on the cucumber plant leaves. In conclusion, both exposure level and the species composition seem to have an effect on the serum levels of CRP and SAA of exposed workers. The greenhouse workers were exposed to only a few species characterized as human pathogens.

Bioaerosols in the landfill environment: an overview of microbial diversity and potential health hazards

Landfilling is one of the indispensable parts of solid waste management in various countries. Solid waste disposed of in landfill sites provides nutrients for the proliferation of pathogenic microbes which are aerosolized into the atmosphere due to the local meteorology and various waste disposal activities. Bioaerosols released from landfill sites can create health issues for employees and adjoining public. The present study offers an overview of the microbial diversity reported in the air samples collected from various landfill sites worldwide. This paper also discusses other aspects, including effect of meteorological conditions on the bioaerosol concentrations, sampling techniques, bioaerosol exposure and potential health impacts. Analysis of literature concluded that landfill air is dominated by microbial dust or various pathogenic microbes like Enterobacteriaceae, Staphylococcus aureus, Clostridium perfringens, Acinetobacter calcoaceticus and Aspergillus fumigatus. The bioaerosols present in the landfill environment are of respirable sizes and can penetrate deep into lower respiratory systems and trigger respiratory symptoms and chronic pulmonary diseases. Most studies reported higher bioaerosol concentrations in spring and summer as higher temperature and relative humidity provide a favourable environment for survival and multiplication of microbes. Landfill workers involved in solid waste disposal activities are at the highest risk of exposure to these bioaerosols due to their proximity to solid waste and as they practise minimum personal safety and hygiene measures during working hours. Workers are recommended to use personal protective equipment and practise hygiene to reduce the impact of occupational exposure to bioaerosols.

Bioaerosols in the Athens Metro: Metagenetic insights into the PM10 microbiome in a naturally ventilated subway station

To date, few studies have examined the aerosol microbial content in Metro transportation systems. Here we characterised the aerosol microbial abundance, diversity and composition in the Athens underground railway system. PM₁₀ filter samples were collected from the naturally ventilated Athens Metro Line 3 station "Nomismatokopio". Quantitative PCR of the 16S rRNA gene and high throughput amplicon sequencing of the 16S rRNA gene and internal transcribed spacer (ITS) region was performed on DNA extracted from PM₁₀ samples. Results showed that, despite the bacterial abundance (mean = 2.82 × 10⁵ 16S rRNA genes/m³ of air) being, on average, higher during day-time and weekdays, compared to night-time and weekends, respectively, the differences were not statistically significant. The average PM₁₀ mass concentration on the platform was 107 μg/m³. However, there was no significant correlation between 16S rRNA gene abundance and overall PM₁₀ levels. The Athens Metro air microbiome was mostly dominated by bacterial and fungal taxa of environmental origin (e.g. Paracoccus, Sphingomonas, Cladosporium, Mycosphaerella, Antrodia) with a lower contribution of human commensal bacteria (e.g. Corynebacterium, Staphylococcus). This study highlights the importance of both outdoor air and commuters as sources in shaping aerosol microbial communities. To our knowledge, this is the first study to characterise the mycobiome diversity in the air of a Metro environment based on amplicon sequencing of the ITS region. In conclusion, this study presents the first microbial characterisation of PM₁₀ in the Athens Metro, contributing to the growing body of microbiome exploration within urban transit networks. Moreover, this study shows the vulnerability of public transport to airborne disease transmission.

Impact of negative pressure system on microbiological air quality in a Central Sterile Supply Department

OBJECTIVE

Guidelines recommend that the cleaning area in a Central Sterile Supply Department (CSSD) maintain a negative pressure of the environmental air, but how much this system can impact the contamination of the air by bioaerosols in the area is not known. The objective of this study was to assess the impact of negative pressure on CSSD by evaluating the microbiological air quality of this sector.

METHODS

Microbiological air samples were collected in two CSSD in the same hospital: one with and one without a negative air pressure system. Outdoor air samples were collected as a comparative control. Andersen six-stage air sampler was used to obtain the microbiological air samples.

RESULTS

The concentration of bioaerosols in the CSSD without negative pressure was 273.15 and 206.71 CFU/m3 , while in the CSSD with negative pressure the concentration of bioaerosols was 116.96 CFU/m3 and 131.10 CFU/m3 . The number of isolated colonies in the negative pressure CSSD was significantly lower (P = .01541).

CONCLUSION

The findings showed that the negative pressure system in the CSSD cleaning area contributed to the quantitative reduction in bioaerosols. However, the concentration of bioaerosols was lower than that established in the guideline for indoor air quality of many countries. Therefore, it cannot be concluded that CSSDs which do not have a negative pressure system in their cleaning area offer occupational risk.

Indoor exposure levels of bacteria and fungi in residences, schools, and offices in China: A systematic review

Microbes in buildings have attracted extensive attention from both the research community and the general public due to their close relationship with human health. However, there still lacks comprehensive information on the indoor exposure level of microbes in China. This study systematically reviews exposure levels, the community structures, and the impact factors of airborne bacteria and fungi in residences, schools, and offices in China. We reviewed the major literature databases between 1980 and 2019 and selected 55 original studies based on a set of criteria. Results show that the concentration of indoor bacteria varies from 72.5 to 7500 CFU/m³ , with a median value of 1000 CFU/m³ , and the concentration of fungi varies from 12 to 9730 CFU/m³ , with a median value of 526 CFU/m³ . The concentration level of microbes varies in different climate zones, with higher bacterial concentrations in the severe cold zone, and higher fungal concentrations in the hot summer and warm winter zone. Among different buildings, classrooms have the highest average bacteria and fungi levels. This review reveals that a unified assessment system based on health effects is needed for evaluating the exposure levels of bacteria and fungi.

Aerosol-to-Hydrosol Sampling and Simultaneous Enrichment of Airborne Bacteria For Rapid Biosensing

Rapid monitoring of biological particulate matter (Bio-PM, bioaerosols) requires an enrichment technique for concentrating the Bio-PM dispersed in the air into a small volume of liquid. In this study, an electrostatic air sampler is employed to capture aerosolized test bacteria in a carrier liquid (aerosol-to-hydrosol (ATH) enrichment). Simultaneously, the captured bacteria are carried into a fluid channel for hydrosol-to-hydrosol (HTH) enrichment with Concanavalin A coated magnetic particles (CMPs). The ATH enrichment capacity of the air sampler was evaluated with an aerosol particle counter for the following test bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Acinetobacter baumannii. Then, the HTH enrichment capacity for the ATH-collected sample was evaluated using the colony-counting method, scanning electron microscopy based image analysis, fluorescence microscopy, electrical current measurements, and real-time quantitative polymerase chain reaction (qPCR). The ATH and HTH enrichment capacities for the given operation conditions were up to 80 000 and 14.9, respectively, resulting in a total enrichment capacity of up to 1.192 × 10⁶. Given that air-to-liquid enrichment required to prepare detectable bacterial samples for real-time qPCR in field environments is of the order of at least 10⁶, our method can be used to prepare a detectable sample from low-concentration airborne bacteria in the field and significantly reduce the time required for Bio-PM monitoring because of its enrichment capacity.

A Comparative Study of Associated Microbiota Between Pig Farm and Pig Slaughterhouse in Guangdong, China

The goal of this study was to compare the microbiota in different pig-present settings in China. Bioaerosol samples from pig farms and slaughterhouses and nasal samples from pig farmers and slaughterhouse workers were collected in Guangdong, southern China. The bacterial genomic DNA was isolated and subjected to 16S sequencing. The data were analyzed using QIIME2 with the DADA2 pipeline. A total of 14,923,551 clean reads and 2785 operational taxonomic units (OTUs) were obtained, which were mostly grouped into 4 phyla (Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria) and 220 families. The microbiota richness of nasal samples in pig-present workers was higher than that of bioaerosols collected in the vicinity of the pig enclosures. There were 31.7% (620/1954) shared OTUs between pig farm bioaerosols and pig farmers which was higher than that between pig slaughterhouses and slaughterhouse workers (23.4%, 364/1553) (p < 0.001). Acinetobacter and Pseudomonas were the most abundant in pig-present bioaerosols, and Staphylococcus, Pseudomonas, and Corynebacterium were dominant bacterial genus in pig farmers. The bacterial patterns are also specific to the location of sample collected. The results suggest that bioaerosol microbiota interact with human nasal microbes in the vicinity of the pig farm enclosures, providing the basis for further analysis of microbial transmission across hosts in pig-present settings.

Enhanced removal of antibiotic resistance genes and mobile genetic elements during sewage sludge composting covered with a semi-permeable membrane

Transmission of antibiotic resistance genes (ARGs) via air media, such as particulate matter, has been intensively investigated due to human exposure through inhalation. However, whether particulate matter originating from the atmospheric environment of composting plants can impact ARG abundance during composting is unknown. Here, we investigated the effects of the atmospheric environment of composting plants on ARG abundance during sewage sludge composting using semi-permeable membrane-covered thermophilic composting (smTC) and conventional thermophilic composting (cTC). After smTC treatment, the total abundances of ARGs and mobile genetic elements (MGEs) decreased by 42.1 % and 38.1 % compared with those of the initial phase, respectively, but they increased by 4.5- and 1.6-fold after cTC, respectively. This result suggested that smTC was more efficient at decreasing ARGs and MGEs than cTC, mainly due to a significant reduction in bacterial contamination from the atmospheric environment of composting plants that accelerated the resurgence of ARGs and MGEs. Furthermore, culture experiments demonstrated that the abundance and diversity of antibiotic-resistant bacteria during the mature phase of smTC were also significantly (P <  0.05) lower than those in the cTC treatment. Thus, covering composting with a semi-permeable membrane could decrease the risk of ARGs spreading.

Size-resolved dynamics of indoor and outdoor fluorescent biological aerosol particles in a bedroom: A one-month case study in Singapore

This study evaluated the interrelations between indoor and outdoor bioaerosols in a bedroom under a living condition. Two wideband integrated bioaerosol sensors were utilized to measure indoor and outdoor particulate matter (PM) and fluorescent biological airborne particles (FBAPs), which were within a size range of 0.5-20 μm. Throughout this one-month case study, the median proportion of FBAPs in PM by number was 19% (5%; the interquartile range, hereafter) and 17% (3%) for indoors and outdoors, respectively, and those by mass were 78% (12%) and 55% (9%). According to the size-resolved data, FBAPs dominated above 2 and 3.5 μm indoors and outdoors, respectively. Comparing indoor upon outdoor ratios among occupancy and window conditions, the indoor FBAPs larger than 3.16 μm were dominated by indoor sources, while non-FBAPs were mainly from outdoors. The occupant dominated the indoor source of both FBAPs and non-FBAPs. Under awake and asleep, count- and mass-based mean emission rates were 45.9 and 18.7 × 10⁶ #/h and 5.02 and 2.83 mg/h, respectively. Based on indoor activities and local outdoor air quality in Singapore, this study recommended opening the window when awake and closing it during sleep to lower indoor bioaerosol exposure.

Monitoring antibiotic resistomes and bacterial microbiomes in the aerosols from fine, hazy, and dusty weather in Tianjin, China using a developed high-volume tandem liquid impinging sampler

Accurate quantification of the airborne antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) is critically important to assess their health risks. However, the currently widely used high-volume filter sampler (HVFS) often causes the desiccation of the sample, interfering with subsequent bacterial culture. To overcome this limitation, a high-volume tandem liquid impinging sampler (HVTLIS) was developed and optimized to investigate the airborne bacterial microbiomes and antibiotic resistomes under different weathers in Tianjin, China. Results revealed that HVTLIS can capture significantly more diverse culturable bacteria, ARB, and ARGs than HVFS. Compared with fine and hazy weathers, dusty weather had significantly more diverse and abundant airborne bacteria, ARGs, and human opportunistic pathogens with the resistance to last-resort antibiotics of carbapenems and polymyxin B, implicating a potential human health threat of dusty bioaerosols. Intriguingly, we represented the first report of Saccharibacteria predominance in the bioaerosol, demonstrating that the potential advantage of HVTLIS in collecting airborne microbes.

Bioaerosols at plants processing materials of plant origin-a review

Due to the dynamic development of industry, related to the processing of plant materials and a subsequent significant increase in the number of employees working in this kind of industry, the indoor air quality is of great importance for the human health. The premises of plants processing plant materials are a specific environment, related to exposure to biological agents. The major sources of microbial contamination of premises are employees' activities and the operation of devices used in the production process, quality of plant materials, technological processes, construction materials, ventilation (air-conditioning) systems, and outdoor air. Biological agents (primarily bacteria and fungi) transported in the air can cause numerous adverse health outcomes in exposed workers.

Workplace Biological Risk Assessment: Review of Existing and Description of a Comprehensive Approach

Biological risks potentially affect workers in multiple occupational sectors through their exposure to pathogenic agents. These risks must be carefully assessed to prevent adverse health effects. This article identifies and critically analyzes approaches that manage the qualitative evaluation of biological risk (EvBR) as part of occupational health and safety prevention, for which no standard method yet exists. Bibliographic and computing references were searched to identify qualitative EvBR approaches, which were then analyzed based on defined criteria, such as the risks studied and the type of assessment. Approaches proposing the most representative types of assessment were analyzed. EvBR approaches in an occupational setting were identified in 32 sources. “Workstation analysis” combined with “assessment by risk level” were the most common approaches. The predominant risk descriptors (RDs) were defined in a characterized and quantifiable way, and a variety of hazard levels and exposure indices were created. Overall, the risk was determined by summing or multiplying the hazard level and exposure indicators. The results confirmed that no methodological consensus currently exists regarding the EvBR and no approach has yet been described that integrates all the parameters to allow for a full assessment of biological risk. Based on the detailed analysis of the existing data, the present paper proposes a general approach.

Fingerprinting ambient air to understand bioaerosol profiles in three different environments in the south east of England

Molecular and chemical fingerprints from 10 contrasting outdoor air environments, including three agricultural farms, three urban parks and four industrial sites were investigated to advance our understanding of bioaerosol distribution and emissions. Both phospholipid fatty acids (PLFA) and microbial volatile organic compounds (MVOC) profiles showed a different distribution in summer compared to winter. Further to this, a strong positive correlation was found between the total concentration of MVOCs and PLFAs (r = 0.670, p = 0.004 in winter and r = 0.767, p = 0.001 in summer) demonstrating that either chemical or molecular fingerprints of outdoor environments can provide good insights into the sources and distribution of bioaerosols. Environment specific variables and most representative MVOCs were identified and linked to microbial species emissions via a MVOC database and PLFAs taxonomical classification. While similar MVOCs and PLFAs were identified across all the environments suggesting common microbial communities, specific MVOCs were identified for each contrasting environment. Specifically, 3,4-dimethylpent-1-yn-3-ol, ethoxyethane and propanal were identified as key MVOCs for the industrial areas (and were correlated to fungi, Staphylococcus aureus (Gram positive bacteria) and Gram negative bacteria, R = 0.863, R = 0.618 and R = 0.676, respectively) while phthalic acid, propene and isobutane were key for urban environments (correlated to Gram negative bacteria, fungi and bacteria, R = 0.874, R = 0.962 and R = 0.969 respectively); and ethanol, 2-methyl-2-propanol, 2-methyl-1-pentene, butane, isoprene and methyl acetate were key for farms (correlated to fungi, Gram positive bacteria and bacteria, R = 0.690 and 0.783, R = 0.706 and R = 0.790, 0.761 and 0.768). The combination of MVOCs and PLFAs markers can assist in rapid microbial fingerprinting of distinct environmental influences on ambient air quality.