Bioaerosols in an industrial park and the adjacent houses: Dispersal between indoor/outdoor, the impact of air purifier, and health risk reduction

Effects and health risk assessments of different spray disinfectants on microbial aerosols in chicken houses

This study aims to explore the effects of spray processes with four different disinfectants on airborne culturable and pathogenic microbial concentrations, microbial community compositions and health risk assessments in chicken houses. Results indicate that compared to the microbial concentrations before spraying, hypochlorous acid, glutaraldehyde-decamethonium bromide and sodium dichloroisocyanate increase culturable bacteria, culturable fungi, airborne Staphylococcus and Candida albicans, respectively. Beyond that, the spray processes with different disinfectants have no significant effects on the microbial concentrations. The total relative abundances (RAs) of the screened out 46 pathogenic bacterial genera decrease after spraying with povidone iodine, while increase after spraying with the other three disinfectants, which is opposite for the 35 pathogenic fungal genera. The core bacterial or fungal genera principally interrelate with each other through cooperation. Ammonia (NH3) concentrations, relative humidity (RH) and temperature (T) influence bacterial communities in aerosols; while fungal communities are mainly affected by T, particulate matters and nitrous oxide (N2O) concentrations. Long-term exposure to aerosols in chicken houses have potential adverse effects on human health and the spray processes with different disinfectants exacerbate the health risks of aerosols via inhalation. Hence, different spray disinfectants cannot significantly reduce the microbial aerosols in real chicken farm environments and the cleaning procedures should be comprehensively reviewed and optimized in livestock and poultry farms.

Pollution profiles, pathogenicity, and toxicity of bioaerosols in the atmospheric environment of urban general hospital in China

Airborne microorganisms in hospitals present significant health risks to both patients and employees. However, their pollution profiles and associated hazards in different hospital areas remained largely unknown during the extensive use of masks and disinfectants. This study investigated the characteristics of bioaerosols in an urban general hospital during the COVID-19 pandemic and found that airborne bacteria and fungi concentrations range from 87 ± 35 to 1037 ± 275 CFU/m3 and 21 ± 15 to 561 ± 132 CFU/m3, respectively, with the outpatient clinic and internal medicine ward showing the highest levels. The operating room (OR) and clinical laboratory (LA) had lower bioaerosol levels but higher microbial activities, suggesting that disinfection procedures used to clean bioaerosols may change them into a viable but non-culturable state. The dominant fungi were Cladosporium, Aspergillus, and Penicillium, while the most common viruses were human associated gemykibivirus 2 and human alpha herpesvirus 1. Besides, the dominant pathogens were Staphylococcus aureus, Salmonella enterica, and Pseudomonas aeruginosa. Bacitracin and macrolides resistance genes bacA and ermC were the most prevalent subtypes of antibiotic resistance genes. Compared to the control sample, hospital-acquired bioaerosols, particularly from the outpatient examination room and emergency room can trigger higher levels of inflammatory factors and cell toxicity but lower cell proliferation rates. Lower cell toxicity was observed in low-risk areas (intensive care unit, LA, and OR). This study provides a new method for assessing bioaerosol health risks and enhances understanding of nosocomial and opportunistic infections and their control.

Distribution characteristics and seasonal variation of microbial communities in powdered infant formula processing environment

The powdered infant formula (PIF) processing environment, as an industrial production site, provides a habitat conducive to microbial aggregation and colonization. However, the distribution and dynamics of microbial communities within this environment remain inadequately characterized. In this study, microbial community analysis was conducted using high-throughput sequencing on samples collected from the full production chain of 8 PIF factories. The sampling encompassed various types (raw milk, staff, air, equipment, wall and ground, and others) during two different seasons (summer and winter). The microbial diversity, composition, and dominant species varied across different groups. Potential source tracking analysis revealed close interactions between staff, air, and surface samples, indicating a potential risk of microbial transfer between staff and the processing environment. The β-nearest taxon index based null model showed that stochastic processes predominantly governed microbial community assembly across all groups. Positive interspecies interactions within the network structure, observed across different seasons and sample types, played a vital role in stabilizing and assembling microbial communities. Notably, the microbiota association networks of summer were more complex but demonstrated higher susceptibility to external disturbances. Conversely, the network structure of surface samples was more robust than that of other types of samples. These findings have improved our understanding of the microbial community distribution patterns in PIF processing environments, facilitating the prospective prediction and assessment of potential microbial sources and contamination risks in the processing chain, which in turn guides the implementation of refined control measures.

Concentration, pathogenic composition, and exposure risks of bioaerosol in large indoor public environments: A comparative study of urban and suburban areas

Biological contamination in larger indoor environments can lead to the outbreak of various infectious diseases. This study aimed to compare the pollution profiles and associated health risks of airborne microorganisms in different indoor settings between urban and suburban areas by culturing, sequencing, and toxicological evaluation. The results indicated that the average level of culturable bacteria was higher in urban areas (955 ± 259 CFU/m3) compared to suburban areas (850 ± 85 CFU/m3), with the highest concentrations found in the market (2170 ± 798 CFU/m3) and gymnasium (2010 ± 300 CFU/m3). Conversely, the total number of airborne bacteria was higher in classroom (2.09 × 105) and laboratory (1.95 × 105 copies/m3), likely due to the presence of viable but non-culturable cells. Additionally, the concentrations of 0.5-2.0 μm total particles were higher in the market and cafeteria. Dominant airborne genera included Acinetobacter and Pseudomonas for bacteria, Cladosporium and Aspergillus for fungi, as well as Geneviridae and Herpesviridae for viruses. Bacterial and viral diversity and richness were significantly higher in suburban areas compared to urban areas, with distinct viral communities observed in hospital. Cytotoxicity assays revealed lower viability of cells in response to bioaerosols from the library (52.3 %) and laboratory (54.5 %); while lower proliferation rates were found for the cells exposed to bioaerosol from gymnasium (5.4 %) and market (6.0 %), suggesting higher toxicity of these environments. Additionally, bioaerosol exposure may impair cellular innate immunity by increasing the expression of IL-6, IL-8, TNF-α, IFN-γ. Our findings provide valuable information for assessing and controlling bioaerosol-related health risks in indoor environments.

Exploring the long-term performance of air purifiers in removing particulate matter and formaldehyde across different residential environments

Household air purifiers are widely used to enhance indoor air quality. However, limited information exists regarding the factors that influence their long-term performance. This study investigates the impact of various residential environments on the long-term efficacy of air purifiers. We deployed household air purifiers in three distinct environments: oily fumes (Group A), non-oily fumes (Group C), and a mixture of oily and non-oily fumes (Groups B-I and B-II). The selected air filter consisted of melt-blown polypropylene and activated carbon, materials commonly employed in commercial applications. The results demonstrated that the control efficiency of air purifiers in non-oily fume environments surpassed that in oily fume environments. After 12 months of operation, particulate matter (PM) concentrations rose by 92.7% and 76.5% in oily and non-oily fume environments, respectively. This increase was primarily attributed to the loss of electrostatic attraction in the polypropylene material due to the organic matter in oily particulate matter. After operating for 1000 h, the clean air delivery rate (CADR) attenuation rates for particulate matter were 70.6%, 19.9%, 16.7%, and 12.5% in Groups A, B-I, B-II, and C, respectively. The CADR attenuation rates for formaldehyde were 80.6%, 48.4%, 38.9%, and 37.3% in the same groups. Additionally, we developed a real-time prediction model for the service life of air purifiers using data from online sensors. When operated for 12 h daily at varying PM concentrations, the filters had an expected service life of 29-97 days in non-oily fume environments and 66-220 days in oily fume environments.

Associations of indoor airborne microbiome with lung function: evidence from a randomized, double-blind, crossover study of microbial intervention

Microorganisms constitute an essential component of the indoor ecosystem and may pose potential health risks after inhalation. However, evidence regarding the impact of indoor airborne microbiome on general respiratory health is scarce. Additionally, while air purification has been shown to be an effective strategy for controlling culturable bioaerosols, its impact on indoor airborne microbiome remains unclear. To determine the impact of indoor airborne microbial exposure on lung function, and whether and how air purification can modify indoor airborne microbiome, we conducted a randomized, double-blind, crossover study employing air purification intervention among 68 healthy young adults in Beijing, China. Indoor airborne bacteria and fungi were characterized using amplicon sequencing technology and quantified by qPCR. Our results indicated positive associations between indoor airborne microbial α-diversity and lung function indices; however, adverse effects from total microbial load were observed. Males were more susceptible to microbial exposure than females. Beneficial effects from richness in Actinobacteria, Bacteroidia, Oxyphotobacteria, Bacilli, Clostridia, Alphaproteobacteria, Gammaproteobacteria, Dothideomycetes, and Sordariomycetes, and detrimental effects from five Proteobacteria genera, including Dechloromonas, Hydrogenophaga, Klebsiella, Pseudomonas, and Tolumonas, were also identified. Air purification contributed to decreased fungal diversity and total fungal load, but not the overall microbial community structure. Our study demonstrates the significant role of indoor airborne microbiome in regulating human respiratory health and provides inspiration for improving health through manipulation of indoor microbiome. Meanwhile, our study also underscores the importance of balancing the potential benefits from decreased microbial load and the underlying risks from reduced microbial diversity while applying environmental microbial interventions.

A potential bioaerosol source from kitchen chimneys in restaurants

Bioaerosols are ubiquitous and have a substantial impact on the atmosphere and human health. Despite the identification of numerous bioaerosol emission sources, the contribution of anthropogenic sources remains inadequately understood. In kitchens, oil stains accumulated at the vent may discharge microorganisms into the environment with airflow, potentially discharging bioaerosol pollution. This putative anthropogenic source of bioaerosols has been long ignored. To investigated whether kitchen chimneys can be a potential source for bioaerosols, air samples, oil stains from in/out chimneys, and surface sand samples were collected near several commercial restaurants. PCoA showed that sampling sites significantly impacted microbiomes, whereas SourceTracker analysis led to the finding that waste grease significantly contributed to bioaerosol composition. Both findings agree with the kitchen chimney as a source of microbes in bioaerosols in the surrounding environment. Furthermore, despite the low biodiversity, a high proportion of stress-tolerant and potential pathogenic bacteria and fungi were found in residual culinary grease, which may escape into the air causing potential risks to human beings. These results led to the proposal that airborne microbiota can originate from cooking waste grease. Immediate actions should be taken into account to enhance disinfection and sterilization aimed at fume vents.

Indoor/Outdoor airborne microbiome characteristics in residential areas across four seasons and its indoor purification

Bioaerosols are more likely to accumulate in the residential environment, and long-term inhalation may lead to a variety of diseases and allergies. Here, we studied the distribution, influencing factors and diffusion characteristics of indoor and outdoor microbiota pollution in six residential buildings in Guangzhou, southern China over a period of one year. The results showed that the particle sizes of bioaerosol were mainly in the range of inhalable particle size (<4.7 μm) with a small difference among four seasons (74.61 % ± 2.17 %). The microbial communities showed obvious seasonal differences with high abundance in summer, but no obvious geographical differences. Among them, the bacteria were more abundant than the fungi. The dominant microbes in indoor and outdoor environments were similar, with Anoxybacillu, Brevibacillus and Acinetobacter as the dominant bacteria, and Cladosporium, Penicillium and Alternaria as the dominant fungi. The airborne microbiomes were more sensitive to temperature and particulate matter (PM2.5, PM10) concentrations. Based on the Sloan neutral model, bacteria were more prone to random diffusion than fungi, and the airborne microbiome can be randomly distributed in indoor and outdoor environments and between the two environments in each season. Bioaerosol in indoor was mainly from outdoor. The health risk evaluation showed that the indoor inhalation risks were higher than those outdoor. The air purifier had a better removal efficiency on 1.1-4.7 μm microorganisms, and the removal efficiency on Gram-negative bacteria was better than that on Gram-positive bacteria. This study is of great significance for the risk assessment and control of residential indoor bioaerosol exposure.

The abundance and pathogenicity of microbes in automobile air conditioning filters across the typical cities of China and Europe

Bioaerosols are widely distributed in urban air and can be transmitted across the atmosphere, biosphere, and anthroposphere, resulting in infectious diseases. Automobile air conditioning (AAC) filters can trap airborne microbes. In this study, AAC filters were used to investigate the abundance and pathogenicity of airborne microorganisms in typical Chinese and European cities. Culturable bacteria and fungi concentrations were determined using microbial culturing. High-throughput sequencing was employed to analyze microbial community structures. The levels of culturable bioaerosols in Chinese and European cities exhibited disparities (Analysis of Variance, P < 0.01). The most dominant pathogenic bacteria and fungi were similar in Chinese (Mycobacterium: 18.2-18.9 %; Cladosporium: 23.0-30.2 %) and European cities (Mycobacterium: 15.4-37.7 %; Cladosporium: 18.1-29.3 %). Bartonella, Bordetella, Alternaria, and Aspergillus were also widely identified. BugBase analysis showed that microbiomes in China exhibited higher abundances of mobile genetic elements (MGEs) and biofilm formation capacity than those in Europe, indicating higher health risks. Through co-occurrence network analysis, heavy metals such as zinc were found to correlate with microorganism abundance; most bacteria were inversely associated, while fungi exhibited greater tolerance, indicating that heavy metals affect the growth and reproduction of bioaerosol microorganisms. This study elucidates the influence of social and environmental factors on shaping microbial community structures, offering practical insights for preventing and controlling regional bioaerosol pollution.

The impact of bioaerosol trajectories on microbial community assembly and physicochemical dynamics in the atmosphere

This study explored the assembly mechanisms and physicochemical dynamics of microbial communities within atmospheric bioaerosols, focusing on the influence of different aerial trajectories. Over two years, samples near Seoul were classified into 'North', 'Southwest', and 'Others' categories based on their aerial trajectories. Physicochemical analysis of the PM2.5 particles revealed distinct ion compositions for each cluster, reflecting diverse environmental influences. Microbial community analysis revealed that shared dominant bacterial phyla were present in all clusters. However, distinct taxonomic profiles and biomarkers were also evident, such as coastal bacteria in the 'Southwest' cluster correlating with wind speed, and arid soil-originated bacteria in the 'North' cluster correlating with cations. These findings demonstrate that biomarkers in each cluster are representative of the distinct environments associated with their aerial trajectories. Notably, cluster 'Southwest' the highest microbial diversity and a strong alignment with the neutral community model, suggesting a large influence of passive dispersal from marine environments. Contrarily, 'North' and 'Others' were more influenced by niche-dependent factors. This study highlights the complex interplay between environmental factors and microbial dynamics in bioaerosols and provides important insights for environmental monitoring and public health risk assessment.

Characteristics and health impacts of bioaerosols in animal barns: A comprehensive study

Bioaerosols produced during animal production have potential adverse effects on the health of workers and animals. Our objective was to investigate characteristics, antibiotic-resistance genes (ARGs), and health risks of bioaerosols in various animal barns. Poultry and swine barns had high concentrations of airborne bacteria (11156 and 10917 CFU/m3, respectively). Acinetobacter, Clostridium sensu stricto, Corynebacterium, Pseudomonas, Psychrobacter, Streptococcus, and Staphylococcus were dominant pathogenic bacteria in animal barns, with Firmicutes being the most abundant bacterial phylum. Based on linear discriminant analysis effect size (LEfSe), there were more discriminative biomarkers in cattle barns than in poultry or swine barns, although the latter had the highest abundance of bacterial pathogens and high abundances of ARGs (including tetM, tetO, tetQ, tetW sul1, sul2, ermA, ermB) and intI1). Based on network analyses, there were higher co-occurrence patterns between bacteria and ARGs in bioaerosol from swine barns. Furthermore, in these barns, relative abundance of bacteria in bioaerosol samples was greatly affected by environmental factors, mainly temperature, relative humidity, and concentrations of CO2, NH3, and PM2.5. This study provided novel data regarding airborne bio-contaminants in animal enclosures and an impetus to improve management to reduce potential health impacts on humans and animals.

Acid etching post-treatment enhanced fungal sterilization performance of copper-manganese-cerium oxide in liquid and aerosol: Materials and molecular biological mechanisms

Bioaerosol is one of the main ways to spread respiratory infectious diseases. In order to further improve the sterilization efficiency of copper-manganese-cerium oxide (CuMnCeOx), the post-treatment method based on acid etching was adopted. The results showed that sterilization efficiency of the treated CuMnCeOx could reach 99% in aerosol with space velocity of 1400 h-1. L(+)-ascorbic acid successfully promoted the formation of Cu+, oxygen vacancies and the generation of reactive oxygen species (ROS) on the surface of the treated CuMnCeOx. During sterilization in liquid system, the transcriptome identified 316 differentially expressed genes, including 270 up-regulated genes and 46 down-regulated genes. Differentially expressed genes were significantly enriched in cell wall (GO:0005618) and external encapsulating structure (GO:0030312). Up-regulated genes were shown in regulation of reactive oxygen species biosynthetic processes (GO:1903409, GO:1903426, GO:1903428) and positive regulation all of reactive oxygen species metabolic process (GO:2000379), indicating that ROS induced cell death by destroying cell wall.

Bioaerosols in the coastal region of Qingdao: Community diversity, impact factors and synergistic effect

Atmospheric bioaerosols are influenced by multiple factors, including physical, chemical, and biotic interactions, and pose a significant threat to the public health and the environment. The nonnegligible truth however is that the primary driver of the changes in bioaerosol community diversity remains unknown. In this study, putative biological association (PBA) was obtained by constructing an ecological network. The relationship between meteorological conditions, atmospheric pollutants, water-soluble inorganic ions, PBA and bioaerosol community diversity was analyzed using random forest regression (RFR)-An ensemble learning algorithm based on a decision tree that performs regression tasks by constructing multiple decision trees and integrating the predicted results, and the contribution of different rich species to PBA was predicted. The species richness, evenness and diversity varied significantly in different seasons, with the highest in summer, followed by autumn and spring, and was lowest in winter. The RFR suggested that the explanation rate of alpha diversity increased significantly from 73.74 % to 85.21 % after accounting for the response of the PBA to diversity. The PBA, temperature, air pollution, and marine source air masses were the most crucial factors driving community diversity. PBA, particularly putative positive association (PPA), had the highest significance in diversity. We found that under changing external conditions, abundant taxa tend to cooperate to resist external pressure, thereby promoting PPA. In contrast, rare taxa were more responsive to the putative negative association because of their sensitivity to environmental changes. The results of this research provided scientific advance in the understanding of the dynamic and temporal changes in bioaerosols, as well as support for the prevention and control of microbial contamination of the atmosphere.

Seasonal variations of airborne microbial diversity in waste transfer stations and preventive effect on Streptococcus pneumoniae induced pulmonary inflammation

Environment, location, and season are important factors that influence the microbiological community, yet, little research on airborne microorganisms in waste transfer stations (WTSs). Here, the airborne bacterial and fungal communities at four WTSs during different seasons were analyzed by high-throughput sequencing. The bacteria were isolated by cultural method and screened bacterium alleviate inflammation induced by Streptococcus pneumoniae (Spn) by regulating gut microbiome. The results revealed that collected bioaerosols from the WTSs varied significantly by location and season. Proteobacteria and Pseudomonadota are prevalent in summer and winter, respectively. Ascomycota was predominant in two seasons. Hazard quotients for adults from four WTSs were below one. Three selected potential probiotics were formulated into a microbial preparation with a carrier that effectively prevented inflammation in bacterial and animal experiments. The expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α in Pre group (0.11, 0.17, and 0.48-fold) were significantly lower than Spn group (2.75, 1.71, and 5.01-fold). These mechanisms are associated with changes in gut microbiota composition and short-chain fatty acids (SCFAs) levels, such as affecting Lachnospiraceae lachnospira abundance and acetic acid content. This study provides insights into the potential application of probiotics derived from WTSs as an alternative approach to preventing respiratory infections.

Electroactive, Antibacterial, and Biodegradable Poly(lactic acid) Nanofibrous Air Filters for Healthcare

Poly(lactic acid) (PLA)-based nanofibrous membranes (NFMs) hold great potential in the field of biodegradable filters for air purification but are largely limited by the relatively low electret properties and high susceptibility to bacteria. Herein, we disclosed a facile approach to the fabrication of electroactive and antibacterial PLA NFMs impregnated with a highly dielectric photocatalyst. In particular, the microwave-assisted doping (MAD) protocol was employed to yield Zn-doped titanium dioxide (Zn-TIO), featuring the well-defined anatase phase, a uniform size of ∼65 nm, and decreased band gap (3.0 eV). The incorporation of Zn-TIO (2, 6, and 10 wt %) into PLA gave rise to a significant refinement of the electrospun nanofibers, decreasing from the highest diameter of 581 nm for pure PLA to the lowest value of 264 nm. More importantly, dramatical improvements in the dielectric constants, surface potential, and electret properties were simultaneously achieved for the composite NFMs, as exemplified by a nearly 94% increase in surface potential for 3-day-aged PLA/Zn-TIO (90/10) compared with that of pure PLA. The well regulation of morphological features and promotion of electroactivity contributed to a distinct increase in the air filtration performance, as demonstrated by 98.7% filtration of PM_0.3 with the highest quality factor of 0.032 Pa^-1 at the airflow velocity of 32 L/min for PLA/Zn-TIO (94/6), largely surpassing pure PLA (89.4%, 0.011 Pa^-1). Benefiting from the effective generation of reactive radicals and gradual release of Zn²⁺ by Zn-TIO, the electroactive PLA NFMs were ready to profoundly inactivate Escherichia coli and Staphylococcus epidermidis. The exceptional combination of remarkable electret properties and excellent antibacterial performance makes the PLA membrane filters promising for healthcare.

Preliminary Investigation on Hygienic-Sanitary Quality of Food Vending Machines

The consumption of hot drinks dispensed from vending machines has become a common practice, both in workplaces and during free time. Every day, millions of bulk drinks are sold, but the quality of the products distributed may not always be guaranteed, as it is related to many factors such as the quality of the water, the raw materials used, and the effectiveness of the equipment's cleaning system. The purpose of this study is to evaluate the hygienic-sanitary requirements of hot drinks and vending machine surfaces. The investigation highlighted the microbial contamination of both coffee and vending machine surfaces. Although the "coffee break" is usually considered a moment of pleasure, apparently not subject to specific jurisdiction, the products dispensed can represent a health risk if the hygienic conditions are not fully respected. Therefore, official controls carried out by the Prevention Department represent a suitable way for evaluating and guaranteeing the hygienic-sanitary requirements, providing for corrective actions, when needed, to protect consumers.