Bioaerosol Concentrations Research Articles

Exploring toilet plume bioaerosol exposure dynamics in public toilets using a Design of Experiments approach

Bioaerosols generated during toilet flushing can contribute to the spread of airborne pathogens and cross-contamination in indoor environments. This presents an increased risk of fomite-mediated or aerosol disease transmission. This study systematically investigated the factors contributing to increased bioaerosol exposure following toilet flushing and developed an empirical model for predicting the exposure-relevant bioaerosol concentration. Air in a toilet cubicle was sampled by impaction after seeding with Clostridium difficile spores. Design of Experiments (DoE) main effects screening and full factorial design approaches were then employed to investigate the significant factors that heighten the risk of exposure to bioaerosols post-flush. Our findings reveal that the inoculated bacterial concentration (C), time elapsed after flushing (t), lateral distance (d), and mechanical ventilation (v) are significant predictors of bioaerosol concentration, with p-values < 0.05. The interaction term, C × d showed a marked increase in bioaerosol concentration up to 232 CFU/m3 at the closest proximity and highest pathogen load. The interplay of C and t (C × t) demonstrated a time-dependent attenuation of bioaerosol viability, with concentrations peaking at 241 CFU/m3 immediately post-flush and notably diminishing over time. The lateral distance and time post-flush (d × t) interaction also revealed a gradual decrease in bioaerosol concentration, highlighting the effectiveness of spatial and temporal dilution in mitigating bioaerosol exposure risks. Furthermore, there is an immediate rise in relative humidity levels post-flush, impacting the air quality in the toilet environment. This study not only advances our understanding of exposure pathways in determining bioaerosol exposure, but also offers pivotal insights for designing targeted interventions to reduce bioaerosol exposure. Recommendations include designing public toilets with antimicrobial surfaces, optimizing ventilation, and initiating timely disinfection protocols to prioritise surfaces closest to the toilet bowl during peak exposure periods, thereby promoting healthier indoor environments and safeguarding public health in high-traffic toilet settings.

Characteristics of bioaerosol emissions from a municipal wastewater treatment plant: Health risk assessment and microbial composition

Bioaerosols released from municipal wastewater treatment plants (MWWTPs) contain pathogenic microorganisms, if dispersed into the atmosphere, which pose potential health risks to humans. In this study, the concentrations and size distribution of bioaerosol, factors on the bioaerosol emission, exposure risk, and microbial composition in different treatment units of a MWWTP were investigated. The results showed that bioaerosol was released to different degrees in each treatment unit, with the concentrations of bioaerosol varied widely, ranging from 978 to 3710 CFU/m3. FG and PST were primary bioaerosol emission sources in MWWTP. COD concentration, wind speed (WS) and relative humidity (RH) significantly influenced bioaerosol concentrations. The proportion of inhalable particles (< 4.7 μm) ranged from 51.35 % to 83.33 %, and bioaerosol emitted from WWTP caused a non-carcinogenic risk to children by the exposure risk assessment (HI > 1), which need to be paid more attention. Bacterial, fungal and actinomycete aerosols were detected in each treatment unit of MWWTP. Among these bioaerosols, bacterial aerosol was dominant. Importantly, several pathogenic bacteria including Sphingobium, Brevundimonas, Romboutsia, Arcobacter, Acinetobacter, and Mycobacterium were identified within the airborne bacteria population, most of which originated from wastewater or sludge, particularly in the ambient air of AeT. Pathogenic bacteria from MWWTP should be studied further to determine their long-term behavior and possible health risks.

Integrated assessment of bioaerosol dispersion patterns and infection risk in a typical urban environment: Implications for urban biosecurity management

Exposure to bioaerosols in high-density urban environments will pose a severe threat to human life and health and present significant challenges to the sustainability and resilience of cities. In this study, the aerodynamic dispersion patterns of bioaerosols at two release locations (open and dense areas) under both thermal conditions in Zhongguancun, Beijing, are investigated. By coupling a dose-response model and an improved cellular automaton, the infection risk within exposed populations was assessed, and emergency evacuation strategies for distinct populations in high-risk areas were devised. This study reveals that bioaerosol distribution is notably influenced by factors such as thermal conditions, release locations and pedestrian height. Bioaerosol concentration above the release source decreases with increasing pedestrian height at two release locations. Under the same exposure time, the infection probability of different groups in this area declines with pedestrian height increases, with adult males having the highest and elderly females having the lowest probability. Thermal conditions and building layout near the release source were second only to exposure time in influencing infection probability and evacuation path. Proximity to the release source indicates a high infection probability but a short evacuation distance to safe areas, while downstream areas exhibit lower infection probability but require longer evacuation distances. The layout of buildings near the release source has the most significant effect on evacuation time. Evacuation for high-risk populations should be prioritized upstream or either side of the mainstream. This study aims to mitigate potential biological threats, address challenges in enhancing urban biosecurity management, and enable sustainable urban development.

Variability and health impact of air pollutants and bioaerosols in multi-functional indoor environments with mechanical ventilation system

The condition of indoor environments significantly impacts human daily life and health, where exposure to harmful substances affects the resilience of occupants. To understand the dynamics of indoor air quality and its implications for occupant health thus this study evaluated air pollutant concentration (TVOC, NO2, O3, CO, CO2, PM10, PM2.5, and PM1) and bioaerosol in mechanically ventilated offices, laboratories, corridors, a library and a mechanical workshop. Simultaneous measurements of all air pollutants were performed for 24 h, including non-working hours, while bioaerosol was sampled for fungal identification and quantified via the colony counting method. High concentrations of PM10, PM2.5, PM1, O3 and bioaerosol were found in the mechanical workshop, where these pollutants were strongly related to humidity (p < 0.05) and indoor source contributions. Other air pollutants such as TVOC had the highest concentrations in the office areas during working hours with an average concentration of 361 ± 14.8 μg m−3, while for CO, the highest concentration was observed in the laboratories for both working hours (442 ± 26.0 ppb) and 24 h average concentration (438 ± 22.1 ppb). Dominant species identified in bioaerosol were Aspergillus sp., Geotrichum sp., Fusarium sp., and Penicillium sp., where the exposure to bioaerosol was found to be of low risk to all workers as the hazard quotient (HQ) was <1 for all multi-functional indoor environments. The results from this study suggest that indoor air pollutants and bioaerosol concentrations have a variety of characteristics and source contributions, especially from human activities and indoor sources.

Framework for assessing collection-based photocatalytic oxidation systems in HVAC applications for bioaerosol control

We use a non-dimensional framework to examine the applicability of photocatalytic oxidation (PCO) to reduce bioaerosol concentration in heating, ventilation, and air conditioning (HVAC) systems. Two non-dimensional parameters: collection efficiency and dimensionless photon flux were used to evaluate the performance of two PCO reactor geometries: 1) honeycomb (HC) and 2) parallel plate (PP) since bioaerosol deposition and photon utilization are prerequisites for effective inactivation in collection based PCO systems. Collection efficiencies of the HC for bioaerosols (0.01–10 μm) were modeled by varying aspect ratios from 25 to 100, air velocities from 0.5 to 2 m/s, and charge numbers from 10 to 10000. The collection efficiencies and the photon fluxes of HC and PP were compared using prior literature studies. The modeling results show that larger bioaerosols (5–10 μm) have a higher collection efficiency than other aerosols for low velocities and longer channels. Larger aspect ratios (channels that are longer for a given diameter) are needed than those found in most commercial HC products, since the effects of gravitational settling and diffusion are inadequate for bioaerosol collection. Furthermore, using ionizers to increase the collection efficiency of PCO systems proved ineffective. The efficiency only increased 2 to 5 times for 0.01–1 μm bioaerosols for charge numbers on the order of 1000. These charge numbers may be impractical to obtain for this size range. PP requires longer channel lengths than HC to achieve the same collection efficiencies. However, the PP configuration has better photon utilization characteristics than HC.

Investigating the Impact of Green Space Ratio and Layout on Bioaerosol Concentrations in Urban High-Density Areas: A Simulation Study in Beijing, China

The COVID-19 pandemic significantly impacted global development. Through bioaerosols emitted by human respiration, respiratory infectious diseases, including COVID-19, are transmitted. The bioaerosol concentrations can be affected by the urban climate and morphology. However, the effects of urban green spaces on bioaerosol concentrations remain unclear. Focusing on the dormitory area of Beijing Forestry University, this study first investigated the influence of different green space ratios on the average bioaerosol concentrations using the ENVI-met software. Moreover, both overall and local green space layouts were analyzed for their impact on bioaerosol concentrations. The results indicated that ventilation conditions were the primary factor influencing bioaerosol concentrations. During peak congestion, a 10% increase in the green space ratio resulted in a 2% rise in the average bioaerosol concentration. Furthermore, a distributed layout resulted in a 1.3% higher average bioaerosol concentration than a concentrated layout with an equivalent green space ratio. Enacting strategies such as Roadside Green Spaces Retreat, Road Spaces Expansion, and Intersection Green Spaces Chamfering led to reductions in local bioaerosol concentrations by up to 17.7%, 18.44%, and 12.69%, respectively. This study highlights the importance of adjusting green space layouts in urban high-density areas after the pandemic, reducing the risk of population exposure to bioaerosol concentrations.

Evaluation of pathogen spread risk from excavated landfill

Landfill is a huge pathogen reservoir and needs special attention. Herein, the distribution and spread risk of pathogen were assessed in excavated landfill scenario. The results show that landfill excavation will greatly increase the risk of environmental microbial contamination. The highest total concentration of culturable bacteria among landfill refuse, topsoil and plant leaves was found to be as high as 1010 CFU g−1. Total coliforms, Hemolytic bacteria, Staphylococcus aureus, Salmonella, Enterococci, and Fecal coliforms were detected in the landfill surrounding environment. Notably, pathogens were more likely to adhere to plant leaves, making it an important source of secondary pathogens. The culturable bacteria concentration in the air samples differed with the landfill zone with different operation status, and the highest culturable bacteria concentration was found in the excavated area of the landfill (3.3 × 104 CFU m−3), which was the main source of bioaerosol release. The distribution of bioaerosols in the downwind outside of the landfill showed a tendency of increasing and then decreasing, and the highest concentration of bioaerosols outside of the landfill (6.56 × 104 CFU m−3) was significantly higher than that in the excavated area of the landfill. The risk of respiratory inhalation was the main pathway leading to infection, whereas the HQin (population inhalation hazardous quotient) at 500 m downwind the excavation landfill was still higher than 1, indicating that the neighboring residents were exposed to airborne microbial pollutants. The results of the study provide evidence for bioaerosols control protective measures taken to reduce health risk from the excavated landfill.

Concern about the risk of aerosol contamination from ultrasonic scaler: a systematic review and meta-analysis

BackgroundMany instruments used in dentistry are rotary, such as handpieces, water syringes, and ultrasonic scalers that produce aerosols. The spray created by these instruments can carry, in addition to water, droplets of saliva, blood, and microorganisms, which can pose a risk of infections for healthcare professionals and patients. Due to the COVID-19 pandemic, this gained attention.ObjectiveThe aim was to carry out a systematic review of the evidence of the scope of the aerosol produced by ultrasonic scaler in environmental contamination and the influence of the use of intraoral suction reduction devices.DesignScientific literature was searched until June 19, 2021 in 6 databases: Pubmed, EMBASE, Web of science, Scopus, Virtual Health Library and Cochrane Library, without restrictions on language or publication date. Studies that evaluated the range of the aerosol produced by ultrasonic scaler during scaling/prophylaxis and the control of environmental contamination generated by it with the use of low (LVE) and high (HVE) volume evacuation systems were included.ResultsOf the 1893 potentially relevant articles, 5 of which were randomized controlled trials (RCTs). The meta-analysis of 3 RCTs showed that, even at different distances from the patient’s oral cavity, there was a significant increase in airborne bacteria in the dental environment with the use of ultrasonic scaler. In contrast, when meta-analysis compared the use of HVE with LVE, there was no significant difference (P = 0.40/CI -0.71[-2.37, 0.95]) for aerosol produced in the environment.ConclusionsThere is an increase in the concentration of bioaerosol in the dental environment during the use of ultrasonic scaler in scaling/prophylaxis, reaching up to 2 m away from the patient’s mouth and the use of LVE, HVE or a combination of different devices, can be effective in reducing air contamination in the dental environment, with no important difference between different types of suction devices.

Effect of Dhupana (medicated fumigation) on the microbial concentration in the indoor air in Kumaragara (pediatric OPD and IPD): an experimental study

Abstract Introduction: Bioaerosols causing infectious diseases are a major concern for the environmental safety in hospital indoors. Chemical fumigation used for controlling infectious bioaerosols leads to several health hazards such as allergic reactions, hyperbilirubinemia, carcinogenicity, and toxicity. Corrosion of metal surfaces, bleaching of fabrics, risk of accidental consumption, high cost, unpleasant odor, flammability, and formation of toxic gases are other concerns. In Ayurveda, Dhupana (medicated fumigation) is advocated for controlling invisible agents capable of disease transmission. It can be a safer alternative to chemical fumigation. However, many ingredients of classical Dhupana preparations are rare or impractical to use; hence, a novel “Shodashanga Dhupa” (16-ingredient fumigation preparation) was formulated using easily accessible ingredients of classical Dhupana formulations. Materials and Methods: The antimicrobial and antifungal activities of Shodashanga Dhupa were ascertained by enumerating colony-forming units (CFUs) in the passive air samples obtained from hospital rooms before and after 1 h of Dhupana. These samples were collected on suitable agar media, and the settle plate method was carried out. Results: There was improvement in the Index of Microbial Air Contamination and a statistically significant reduction in bacterial CFUs in the pediatric outpatient department (P = 0.000218) and in the Panchakarma therapy room (P = 0.000218). There was a statistically significant reduction in fungal CFUs (P = 0.0137) in the pediatric outpatient department and in the Panchakarma therapy room (P = 0.00109) after 1 h of Dhupana. Conclusion: The study suggests that fumigation with common herbs and spices is effective in decreasing bacterial and fungal bioaerosol concentration in the indoor air of hospital rooms, and it can be used as an economical, hassle-free, and safe method of disinfection.

Effect of airflow rate on CO2 concentration in downflow indoor ventilation

We perform direct numerical simulations to study the effect of increasing airflow rate on CO2 concentration in downflow and displacement ventilation in a room with one occupant. Often, CO2 concentration is used as a proxy for the concentration of bio-aerosols of respiratory droplets, and therefore, tracking the CO2 concentration in ventilation strategies can be useful to understand and quantify the risk of spread of communicable respiratory illnesses. At low to moderate airflow rates, the flow in the downflow setup is not mixed, but stratified. The CO2 concentration in the upper and lower layers is determined by the strength of the thermal plume originating from the occupant. We provide a simple theoretical model to predict the height of the stratified interface, the volumetric flux of the ascending plume, and the CO2 concentration in the lower and upper layers. At very high airflow rates, the flow is well-mixed and the average CO2 concentration in the room can be predicted with the mixing ventilation assumption. We demonstrate that at low to moderate airflow rates, displacement ventilation more effectively maintains lower CO2 concentrations in the lower layer compared to downflow ventilation.

Forecasting and alert of atmospheric bioaerosol concentration profile based on adaptive genetic algorithm back propagation neural network, atmospheric parameter and fluorescence lidar

Bioaerosols are biologically originated particles in the atmosphere, which is mainly composed of bacteria, fungi, viruses, pollen, spores, and the fragmentation and disintegration of plants and animals. Bioaerosols are easy to be spread in the lower atmosphere and cause various epidemic diseases, which is harmful to human health. The forecasting and alert of bioaerosols have important scientific significance and reality needs. In this paper, a method is proposed for estimating and predicting the concentration profile of atmospheric bioaerosols using fluorescence lidar observational data. Using the powerful nonlinear prediction ability of artificial neural networks and through repeated training, a mathematical model can be established for the relationship among atmospheric environment, meteorological parameters, and bioaerosol concentration profiles. The input parameters are temperature and humidity, aerosol extinction coefficient, backscatter coefficient, PM2.5, PM10, SO2, NO2, CO, O3, and wind speed, and outputs the concentration profile of bioaerosols. The prediction results with the measurement relative deviation of genetic algorithm back propagation (GA-BP) neural network and adaptive genetic algorithm back propagation (AGA-BP) neural network were analyzed. The results indicate that the AGA-BP neural network can effectively predict the concentration distribution of bioaerosols, and the predicted concentrations of bioaerosols are 1793 particles × m−3, 3088 particles × m−3, 5261 particles × m−3, 7410 particles × m−3 and 9133 particles × m−3 for air quality with superior, fine, mild contamination, middle level pollution and heavy pollution at an altitude of 0.315 km, respectively. We found that the predicted concentration of pollution weather is much higher than that of good weather. Furthermore, the AGA-BP neural network was used to predict the concentration profiles of atmospheric bioaerosols under different weather conditions, which provided a new research method for forecasting and alert of atmospheric bioaerosols.

Study on the concentration, composition, and recovery rate of bacterial bioaerosols after rainfall in Ho Chi Minh City.

Aerosolized microorganisms have become an important factor in assessing air quality. To determine the characteristics of bacterial bioaerosols in air and rainwater, as well as calculate the recovery rate of bacteria after rains in Ho Chi Minh City, our study was performed using the SKC Biostage sampler for airborne bacteria and Plate Count Agar (PCA) medium for bacterial concentration. Subsequently, the study determined the bacterial community composition at the phylum and order levels using the 16S rRNA (16S metabarcoding) method. Before the rain, bacterial concentrations in the air ranged from 263.39 ± 21.00 to 277.39 ± 78.99CFU/m3, and in rainwater 264.89 ± 51.17 to 285.72 ± 28.00CFU/m3. Following rains, the bacterial concentrations decreased to their lowest levels within the first 1-2h and gradually increased thereafter, reaching their peak after 9h for heavy rain and after 12h for light and moderate rains. The bacterial bioaerosols recovery rate was determined to be 100% for light and moderate rains and 94.6% for heavy rain. The change in bacterial concentration after rainfall showed a positive correlation with temperature (r = 0.85) and CO2 concentration (r = 0.70) and a negative correlation with relative humidity (r = - 0.79). Bacterial composition analysis revealed that the Actinobacteria, Firmicutes, and Proteobacteria phyla were dominant and characteristic of the humid tropical climate in Vietnam. Notably, Firmicutes were the most prevalent phylum both before and after rains. The increased prevalence of certain bacterial orders, particularly Staphylococcus, could contribute to the spread of pathogens, particularly foodborne pathogens. In addition to rain, relative humidity contributed to reducing bacterial bioaerosols concentration and their recovery rate after the rain.

Effects of extreme precipitation on bacterial communities and bioaerosol composition: Dispersion in urban outdoor environments and health risks

Concerns about contaminants dispersed by seasonal precipitation have grown due to their potential hazards to outdoor environments and human health. However, studies on the crucial environmental factors influencing dispersion changes in bacterial communities are limited. This research adopted four-season in situ monitoring and sequencing techniques to examine the regional distribution profiles of bioaerosols, bacterial communities, and risks associated with extreme snowfall versus rainfall events in two monsoon cities. In the early-hours of winter snowfall, airborne cultivable bioaerosol concentrations were 4.1 times higher than the reference exposure limit (500 CFU/m3). The concentration of ambient particles (2.5 μm) exceeded 24,910 particles/L (97 μg/m3), positively correlating with the prevalence of cultivable bioaerosols. These bioaerosols contained cultivable bacterial species such as pathogenic Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Escherichia coli. Bioaerosol concentrations increased by 53.0% during 50-mm snow extremes. Taxonomic analysis revealed that Pseudomonas, Staphylococcus, and Veillonella were the most abundant bacterial taxa in the initial snowmelt samples during winter precipitation. However, their abundance decreased by 87.6% as snowing continued (24 h). Reduced water base cation concentration also led to a 1.15-fold increase in the Shannon index, indicating a similar yet heightened bacterial diversity. Seasonally, Pedobacter and Massilia showed higher relative abundance (25% and 18%, respectively), presenting increased bacterial transmission to the soil. Furthermore, Pseudomonas was identified in 60% of spring snowstorm samples, suggesting long-distance dispersal of pathogenic bacteria. When these atmospheric aerosol particles carrying biological entities (0.65–1.1 μm) penetrated human alveoli, the calculated hazard ratio was 0.55, which as observed in inhalation exposures. Consequently, this study underscores the risk of seasonal precipitation-enhanced ambient bacterial transmission.

Characterizing bioaerosols in PM2.5 in a semi-arid region experiencing desert dust events

Introduction: Fine particulate matter (PM2.5) pollution is a global public health concern, particularly in arid and semi-arid regions that experience dust events. Exposure to PM2.5 has been associated with various short- and long-term health effects, which can be attributed to the composition of the fine particles. This study aimed to assess the concentration of bacteria and fungi in PM2.5 in the air of Isfahan, Iran which experiences air pollution.Methods: A total of thirty-nine PM2.5 samples were collected over 1 year. Bacterial and fungal concentrations associated with PM2.5 were measured using both culture-based method and real-time polymerase chain reaction (PCR).Results: The average concentration of PM2.5 was found to be 56 μg m−3, with many samples exceeding the recommended limit of 15 μg m−3 set by the World Health Organization for PM2.5 in ambient air. The mean culturable bacterial and fungal concentrations were 39 and 4 CFU m−3, respectively which showed a significant difference compared to the results obtained through real-time PCR. No significant correlation was found between the levels of bacterial and fungal cells and PM2.5 concentrations. The dominant phyla found in PM2.5 were Firmicutes and Actinobacteria, while Proteobacteria as Gram-negative bacteria were rarely detected.Discussion: The findings suggest that the climate conditions in Isfahan, characterized by its semi-arid nature with low humidity content, influences the activity and viability of microbial populations, resulting in low concentrations of bioaerosols in PM2.5. Furthermore, it seems that desert dust events do not contribute to increasing the potential health risks associated with bacterial and fungal bioaerosols in PM2.5.

Spatial and temporal distribution of bioaerosols produced by patients with different postures in a negative pressure isolation ward under different ventilation modes

The high concentration of viral bioaerosols within the negative pressure isolation wards could pose a challenge to preventing potential cross-infection amongst healthcare workers (HCWs) and patients. Using the Euler–Lagrange methodology, this study numerically simulated the spatial and temporal distribution characteristics of bioaerosols in a typical negative pressure isolation ward as well as determined the interaction of ventilation mode and patient posture on ward ventilation performance. The removal effect of particle groups produced by two respiratory behaviours (breathing and coughing) was quantitatively analyzed, and the effect of exhaust air ratio and air exchange rate on particle distribution was discussed. The results showed that the migration characteristics of bioaerosol particles were sensitive to both the ventilation pattern and patient posture, which showed significant interactions. On this basis, the ventilation pattern with the best ventilation performance was evaluated, showing a particle removal effect of 70–85%. Due to the initial momentum difference, the diffusion behaviour of cough and breath particles was not consistent, but optimizing the airflow distribution near the exhaust outlet could improve their removal efficiency in the meantime. Further studies found that equal exhaust air velocity ratio facilitated the removal of aerosol particles, and an appropriate increase in the air exchange rate could also reduce the particle content.

Bioaerosol assessment in indoor and outdoor environments: a case study from India

Exposure to bioaerosols has been associated with the occurrence of a variety of health impacts, including infectious illnesses, acute toxic effects, allergies, and cancer. This study aimed at evaluating airborne bacteria and fungi populations at different indoor and outdoor sites on a college campus in Bengaluru, India. Bioaerosol samples were collected using a two-stage Andersen air sampler; and isolates were identified using standard procedures. Six air samples and meteorological data were collected in March and April 2014 to examine the effects of temperature and relative humidity on bioaerosol concentration using linear regression modeling. Among all sites, the canteen showed the highest bioaerosol levels both indoors and outdoors. Specific bacterial identification was not possible, but gram staining and microscopic analysis helped to identify gram positive and gram negative bacteria. The most prevalent fungal species in the samples were Cladosporium, Aspergillus niger, Penicillium, Rhizopus, Fusarium, Mucor, and Alternaria. Due to the impact of weather conditions, such as temperature and relative humidity, the bioaerosol concentration varied greatly at each site according to the regression model. The indoor bioaerosol concentrations at all sites exceeded the values established by the American Industrial Hygiene Association (< 250 CFU/m3 for total fungi and < 500 CFU/m3 for total bacteria). Higher concentrations of bioaerosols may be attributed to the transportation of microbes from the ground surface to suspended particles, the release of microbes from the respiratory tract, higher rate of shredding of human skin cells, and many other factors.

How dominant the load of bioaerosols in PM2.5 and PM10: a comprehensive study in the IGP during winter.

The winter period is most ideal for studying near-surface aerosols in the Indo-Gangetic plains (IGP) of India, since this period is inundated with significantly higher concentrations of aerosols across the unique geographical domain because of shallow atmospheric boundary layer. This study focuses on analysing the concentration of the biotic component of aerosols (bioaerosols) in a central location of the IGP and estimating their dominance in ambient particulate matter (PM) from 2021 to 2023. Observations showed that bioaerosol concentrations also increased significantly with the increasing concentrations of PM2.5 and PM10, suggesting that bioaerosols are a dominant component of the total aerosol load in the atmosphere. The total microbe's concentration (collectively fungi and bacteria) was found to be 94 to 226 cfu m-3 in PM2.5 and 167 to 375 cfu m-3 in PM10 where bacteria contributed 81.12 and 79.99%, respectively. The contribution of fungal spores in PM2.5 and PM10 remained as 18.88 and 20.01%, respectively, in the total microbes in the respective particulate matter. In the bioaerosols, fungi, namely Aspergillus, Cladosporium, and Penicillium, were dominant, and bacteria, namely E. coli, Mammaliicoccus and Enterobacter, were prevalent in both the PM size regimes. The most prominent microbial presence was observed when the temperature ranged between 16 and 20°C and relative humidity between 80 and 85%. The outcomes of the present study will be useful for further research on the health effect of the bioaerosols in the IGP.

Assessment of exposure to fungi in archives and libraries based on analyses of filter and nasal samples: preliminary investigation

The aim of this study was to characterize the occupational exposure to inhalable dust and airborne fungi among archive and library workers based on qualitative and quantitative analyses of stationary and personal filter samples as well as nasal swabs. The study was carried out in 3 archives and 2 libraries and involved 9 workers of these institutions. Airborne fungi and inhalable dust samples were collected by stationary and personal measurements using filter samplers. Additionally, the nasal swabs from workers were taken after work-shift and microbiologically analysed. The average concentrations of inhalable dust and airborne fungi were 49 µg/m3 (SD = 91) and 299 CFU/m3 (SD = 579), respectively. Both dust and bioaerosol concentrations obtained using personal measurements were significantly higher than that measured by stationary sampling. The correlation analysis showed strong relationships between the concentrations of inhalable dust and airborne fungi (R = 0.57; p < 0.001). The fungal concentrations in swab samples from archive workers (median: 104 CFU/ml) were significantly higher than that in swabs from librarians (median: 1.4 CFU/ml). Among the airborne fungi, the widest spectrum of species was found among Penicillium and Aspergillus (including pathogenic A. fumigatus) genera. However, in samples from archives, yeast-like fungi from Sporidiobolus and Candida (including pathogenic C. albicans) genera predominated among isolated mycobiota. The results of this study revealed that airborne fungi were able to efficiently contaminate the nasal cavity of archive and library employees. The analysis of nasal swabs can be considered as an important analytical tool supporting the assessment of workers’ exposure to bioaerosols.

Distribution Characteristics and Factors Influencing Culturable Bacterial Bioaerosols on a Dairy Farm in Northern China

Studying the distribution characteristics of bioaerosols and their interaction with the environment is crucial for dairy farms. The distribution of aerosols differs in dairy farming from farming of other livestock, and their sensitivity to environmental factors varies across sites. Field experiments were conducted in an intensive commercial dairy farm in Northern China to investigate the horizontal and vertical distribution of culturable bacterial bioaerosols. Concentration levels and particle size ranges were analyzed, and the impact of multiple environmental factors on culturable bacterial bioaerosols was assessed. Significant variations in culturable bacterial bioaerosol concentrations were observed across eight functional zones, ranging from 1.14 × 103 to 7.35 × 103 CFU/m3. Culturable bacterial bioaerosols exhibited consistent carrier distribution patterns across six different size ranges. Vertical analysis revealed significantly higher culturable bacterial bioaerosol concentrations at a 1 m height compared to 4 m (p &lt; 0.05), while similar size distributions were observed at different heights of the same sampling location. The top three environmental factors influencing culturable bacterial bioaerosol concentrations were PM100 concentration, wind direction, and air temperature. This study provides insights into the distribution characteristics of culturable bacterial bioaerosols on dairy farms and their response to environmental factors. The findings serve as a reference for evaluating bioaerosol emissions and establishing daily disinfection management measures on dairy farms.

A novel strategy for bioaerosol rapid detection based on broad-spectrum high-efficiency magnetic enrichment and separation combined with ATP bioluminescence

Bioaerosol detection technology represented by laser-induced fluorescence (LIF) cannot effectively detect bioaerosols in the presence of interferents such as plant-derived smoke, industrial waste gas, pollen and pollen debris which can produce strong non-biological fluorescence interference. To overcome this drawback, in this study, a novel method based on broad-spectrum high-efficiency magnetic enrichment and separation combined with adenosine triphosphate (ATP) bioluminescence was proposed for Escherichia coli (E. coli) bioaerosols rapid detection. First, E. coli bioaerosols mixed with interferents were collected. Core-shell Fe3O4@Polydopamine@Polyethyleneimine magnetic particles were used as bioaerosol enrichment materials to enrich E. coli bioaerosol sampling solutions. Subsequently, an ATP bioluminescence assay was performed to determine the concentration of E. coli. A linear relationship was observed between ATP bioluminescence intensity after enrichment and the E. coli bioaerosol concentration in the range of 870–49,098 particles per liter; the bioluminescence intensity measured after enrichment was significantly higher than that before enrichment, and this enrichment method provide a 6-fold better sensitivity in bioaerosol detection. More importantly, this method efficiently enriched and detected bioaerosols in plant-derived smoke. This method can effectively improve the sensitivity of ATP bioluminescence detection, and possesses the advantages of convenient operation and strong anti-interference ability. It also provides a foundation for the effective detection of bioaerosols mixed with interfering substances, and a reference for evaluating the sensitivity and anti-interference of LIF-based instruments.