Distribution Of Bioaerosols Research Articles

Optimal location design for multiple Far-UVC lamps to enhance indoor bioaerosol disinfection by CFD-based Bayesian optimization

In occupied indoor environments, 222 nm far-UVC is a secure and effective approach for controlling the spread of infectious bioaerosols. To enhance the disinfection effectiveness, it is crucial to carefully design the placement of far-UVC lamps, by considering the impact of airflow pattern, bioaerosol distribution, and irradiance exposure. Using CFD alone for designing the locations of multiple lamps presents challenges due to the high computational cost resulting from the high number of potential combinations. Therefore, this study combined CFD with the Bayesian optimization method to improve the computational efficiency, enabling customized design for complex scenarios. The proposed method was first validated with experimental data and the results from the grid search method. Next, the validated method was applied to design the placement of multiple far-UVC lamps in a railway compartment. In the studied railway compartment, just 1 h of optimization led to 1.05-fold–2.87-fold improvement in bioaerosol disinfection efficiency compared to random selection and uniform distribution. This optimization method for customized location design can maximize the utilization of far-UVC lamps, reducing equipment investment and energy consumption while ensuring effective disinfection.

Assessment of the partial partition effect on the control of bioaerosol transmission in a one bed ward

The partition is a boundary that can effectively suppress the spread of bioaerosols. It has been widely used in public places such as restaurants and shopping malls during COVID-19 pandemic. Inspired by this, this study explored the effect of partial partitions in limiting the diffusion of bioaerosols in a typical isolation ward. In bioaerosol experiments, Serratia marcescens was used as bioaerosol releasing material to study the bioaerosol distribution. Simultaneously, the result of bioaerosol sampling was used to validate the numerical model. Furthermore, the effect of five partitions strategies on aerosol diffusion was further explore by Computational fluid dynamics. The flow patterns in the ward and the spatiotemporal distribution of aerosols were obtained and analyzed. The results showed that the best strategy could increase bioaerosol removal effectiveness index from 0.569 to 0.696, which accelerated the bioaerosol removal. Nevertheless, only selecting a reasonable size and installation position, can the partial partition play a positive role in the interruption of aerosol diffusion. Moreover, small-area partial partition can achieve efficient control of bioaerosol diffusion as well.

Spatial distribution of bioaerosols and evaluation of four ventilation method on controlling their diffusion in a typical enhanced biosafety level 2 laboratory

Biosafety laboratories are critical in many fields. However, experimenters associated the infection risk from biological aerosols. In this study, by conducting experiments on the release and collection of bioaerosols within a typical BSL-2 + laboratory, the spatial distribution of bioaerosols was tracked. Numerical calculations were employed to obtain and visualize the airflow patterns and aerosol dispersion paths of four ventilation methods. The results indicated that equipment and tables led to uneven airflow distribution within the laboratory. The comparison results of the four evaluation indicators showed that the air age distribution of UU (Upward supply and upward return) mode and CD (Cross-supply and downward return) mode was superior, with air change efficiency values of 0.595 and 0.603, respectively. Additionally, the contaminant removal index of CD mode was 1.48, significantly higher than the other ventilation methods. The statistical results of the contaminant dispersion index also indicated that CD mode was most conducive to diluting aerosols in the spatial environment. The LD (lateral supply and downward return) mode may lead to airflow short-circuiting. The UD (upward supply and downward return) mode can provide balanced protection for laboratory. Overall, CD mode performed the best among the four ventilation methods, followed by UU mode.

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.

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.

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.

Large-Scale Dust–Bioaerosol Field Observations in East Asia

Abstract The long-range transport of bioaerosols by dust events significantly impacts ecological and meteorological networks of the atmosphere, biosphere, and anthroposphere. Bioaerosols not only cause significant public health risks, but also act as efficient ice nuclei for inducing cloud formation and precipitation in the hydrological cycle. To establish risk management for bioaerosol impacts on the Earth system, a large-scale investigation of bioaerosols must be performed under different environmental conditions. For this purpose, a Dust–Bioaerosol (DuBi) field campaign was conducted to investigate the distribution of bioaerosols by collecting ∼950 samples at 39 sites across East Asia from 2016 to 2021. Concentrations and community structures of bioaerosols were further analyzed using fluorescence microscopic observations and high-throughput DNA sequencing, and these factors were compared to environmental factors, such as PM10 and aridity. The results indicated that microbial concentrations at dryland sites were statistically higher than those at humid sites, while the microbe-to-total-particle ratio was statistically lower in drylands than in humid regions. Microbial cells per microgram of PM10 decreased when PM10 increased. The proportion of airborne particles at each site did not vary substantially with season. The richness and diversity of airborne bacteria were significantly higher in drylands than in semiarid regions, while the community structures were stable among all sampling sites. The DuBi field campaign improves our understanding of bioaerosol characteristic variations along the dust transport pathway in East Asia and the changes of bioaerosols under the trend of climate warming, supporting the efforts to reduce public health risks.

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.

Study on the migration characteristics of bioaerosols and optimization of ventilation patterns in a negative pressure isolation ward considering different patient postures.

Due to the serious global harm caused by the outbreak of various viral infectious diseases, how to improve indoor air quality and contain the spread of infectious bioaerosols has become a popular research subject. Negative pressure isolation ward is a key place to prevent the spread of aerosol particles. However, there is still limited knowledge available regarding airflow patterns and bioaerosol diffusion behavior in the ward, which is not conducive to reducing the risk of cross-infection between health care workers (HCWs) and patients. In addition, ventilation layout and patient posture have important effects on aerosol distribution. In this study, the spatial and temporal characteristics as well as dispersion patterns of bioaerosols under different ventilation patterns in the ward were investigated using the computational fluid dynamics (CFD) technique. It is concluded that changes in the location of droplet release source due to different body positions of the patient have a significant effect on the bioaerosol distribution. After optimizing the layout arrangements of exhaust air, the aerosol concentration in the ward with the patient in both supine and sitting positions is significantly reduced with particle removal efficiencies exceeding 95%, that is, the ventilation performance is improved. Meanwhile, the proportion of aerosol deposition on all surfaces of the ward is decreased, especially the deposition on both the patient's body and the bed is less than 1%, implying that the risk of HCWs being infected through direct contact is reduced.

The impact of high background particle concentration on the spatiotemporal distribution of Serratia marcescens bioaerosol

Airborne transmission is a well-established mode of dissemination for infectious diseases, particularly in closed environments. However, previous research has often overlooked the potential impact of background particle concentration on bioaerosol characteristics. We compared the spatial and temporal distributions of bioaerosols under two levels of background particle concentration: heavily polluted (150–250 μg/m3) and excellent (0–35 μg/m3) in a typical ward. Serratia marcescens bioaerosol was adopted as a bioaerosol tracer, and the bioaerosol concentrations were quantified using six-stage Andersen cascade impactors. The results showed a significant reduction (over at least 62.9%) in bioaerosol concentration under heavily polluted levels compared to excellent levels at all sampling points. The temporal analysis also revealed that the decay rate of bioaerosols was higher (at least 0.654 min-1) under heavily polluted levels compared to excellent levels. These findings suggest that background particles can facilitate bioaerosol removal, contradicting the assumption made in previous research that background particle has no effect on bioaerosol characteristics. Furthermore, we observed differences in the size distribution of bioaerosols between the two levels of background particle concentration. The average bioaerosols size under heavily polluted levels was found to be higher than that under excellent levels, and the average particle size under heavily polluted levels gradually increased with time. In conclusion, these results highlight the importance of considering background particle concentration in future research on bioaerosol characteristics.

On-site investigation of the concentrations and size distributions of bioaerosols in the underground garages

Bioaerosol concentrations and sizes in indoor environment are associated with human health. Among various indoor environments, the knowledge of the bioaerosol characteristics in underground garages remains unclear. In this study, both DAPI (4′,6-diamidino-2-phenylindole) staining and culturable methods were performed to determine the concentrations and size distributions of bioaerosols in two typical underground garages (an office building (UBOB) and a commercial building (UBCB)) in Xi'an, China. Results indicated that bioaerosol concentrations showed seasonal variations in two garages. The total bioaerosol concentrations were higher in summer (UBOB: (1.07 ± 0.29) ✕105 cells/m3; UBCB: (0.59 ± 0.23) ✕105 cells/m3) than winter (UBOB: (0.34 ± 0.17) ✕105 cells/m3; UGCB: (0.38 ± 0.15)✕105 cells/m3). Higher concentrations of bioaerosols were also found during the rush hour than other times due to the elevated traffic volumes. The spatial distribution of bioaerosols was relatively even for most sampling sites in two garages. Moreover, over 80% of airborne culturable fungi and over 65% of airborne culturable bacteria were in respirable size range (<4.7 μm). Importantly, airborne culturable fungal concentrations in two garages exceeded the proposed thresholds by the World Health Organization (WHO) (500 CFU/m3), with the exceeding standard rate (ESR) of 80.28% and 82.60%, respectively, at UGOB and UGCB, implying that necessary control measures should be taken to reduce microorganism contamination in the air of underground garages. The present results may provide the scientific basis for better understanding pollution characteristics of bioaerosols and formulating prevention and control measures in underground garages.

Study on bioaerosol diffusion and deposition in a mobile BSL-4 laboratory based on air age analysis

Biosafety issues have aroused global concern, especially after the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron strain of corona virus disease 2019 (COVID-19) caused incalculable human and property losses. Laboratory-acquired infections (LAIs) caused by improper operations or accidents are frequently reported. Research is urgently needed for a mobile biosafety level-4 (BSL-4) laboratory with a high risk for exposure. Deposition characteristics and the spatial distribution of bioaerosols under two typical cases were studied in this paper. Based on the age of air and simulation of airflow pattern, a detailed analysis of infection risk and the distribution of bioaerosols was conducted. The deposition characteristics of particles on different surfaces were analyzed based on particle tracking technology. The results showed that the removal rate of bioaerosols was lower in the space area of the laboratory from 1.6 m above the ground. The distribution of high-risk areas is affected by the coupling of equipment layout and pollution sources, mainly located downstream of the main airflow in the laboratory, and the particle concentration was eight times that of the low-risk areas. More than half of bioaerosol particles are deposited on laboratory equipment and walls. The number of particles deposited on the wall was the largest, accounting for 25.02% of the total. The unit area deposition ratio of the experimental table was the highest, which was 6.14 %/m2. The main deposition area of each surface was determined, which could be of guiding significance to the determination of the key disinfection location of the mobile BSL-4 laboratory.

Comparison of airborne bacteria and fungi in different built environments in selected cities in five climate zones of China

Bioaerosols in different built environments and climate zones have unique effects on occupant health, which demands comparisons of their characteristics to make targeted control measures. This study investigated bioaerosol distribution in five different climate zones across China with four building types (n = 686 rooms). The results showed significant disparities in bioaerosol concentrations among various buildings and climate zones. The bacterial concentrations in residences (536 ± 647 CFU/m3) were significantly higher than in schools, offices, and hospitals owing to different built environments and human activities. The highest mean value of fungal concentration was found in schools (826 ± 955 CFU/m3) due to their greater landscaping area. The bacterial concentrations in the cold zone (307 ± 506 CFU/m3) and the hot summer and cold winter zone (214 ± 180 CFU/m3) were significantly lower than in the other three climate zones. The fungal concentrations in the severe cold zone (709 ± 900 CFU/m3) and the hot summer and warm winter zone (1094 ± 832 CFU/m3) were significantly higher than in the other three climate zones; the lower the indoor temperature (T) and the higher the air exchange rate, the lower the indoor airborne bacterial concentration; the lower the relative humidity (RH), the lower the indoor airborne fungi. In addition, a higher air exchange rate could also reduce the effect of occupant density on indoor bacterial concentration. The results of this study provide valuable data on bioaerosol profiles in various built environments and climate zones and highlight the significance of T, RH, and air exchange rate on indoor bioaerosol concentrations.

Size distribution and concentration of indoor culturable bacterial and fungal bioaerosols

Exposure to bioaerosols in indoor environments may adversely affect human health. Herein, we present the concentrations and size distributions of bacterial and fungal bioaerosols measured in 5 locations (café, cafeteria, building lobby, classroom, and meeting room) within one building during winter. Sampling was conducted using a six-stage Andersen cascade impactor and the size-specific concentration of culturable bioaerosols was quantified via the colony counting method. The concentration and size distribution of bioaerosols differed among locations. The highest average concentrations of bacterial and fungal bioaerosols were found in the café (170 colony-forming unit [CFU]/m 3 ) and cafeteria (205 CFU/m 3 ). In the winter indoor environment, both fungal and bacterial bioaerosols were concentrated at respirable sizes <3.3 μm, and significant levels of bacterial bioaerosols <1.1 μm were observed in the café. This quantitative characterization of the physical properties of bioaerosols in indoor environments can be used to establish effective protection measures against the health impacts of bioaerosols. • Culturable bioaerosols were determined within a building in winter. • Significant bacterial bioaerosols were observed in the café with high user density. • Bacterial and fungal bioaerosols were concentrated in inhalable sizes <3.3 μm. • Bacterial bioaerosols <1.1 μm were observed in the café and building lobby.

Understanding the influence of the bioaerosol source on the distribution of airborne bacteria in hospital indoor air

The composition and concentration of airborne microorganisms in hospital indoor air has been reported to contain airborne bacteria and fungi concentrations ranged 101–103 CFU/m3 in inpatients facilities which mostly exceed recommendations from the World Health Organization (WHO). In this work, a deeper knowledge of the performance of airborne microorganisms would allow improving the designs of the air-conditioning installations to restrict hospital-acquired infections (HAIs). A solution containing Escherichia coli (E. coli) as a model of airborne bacteria was nebulized using the Collison nebulizer to simulate bioaerosols in various hospital areas such as patients’ rooms or bathrooms. Results showed that the bioaerosol source had a significant influence on the airborne bacteria concentrations since 4.00 102, 6.84 103 and 1.39 104 CFU mL−1 were monitored during the aerosolization for 10 min of urine, saliva and urban wastewater, respectively. These results may be explained considering the quite narrow distribution profile of drop sizes around 1.10–1.29 μm obtained for urban wastewater, with much vaster distribution profiles during the aerosolization of urine or saliva. The airborne bacteria concentration may increase up to 107 CFU mL−1 for longer sampling times and higher aerosolization pressures, causing several cell damages. The cell membrane damage index (ID) can vary from 0 to 1, depending on the genomic DNA releases from bacteria. In fact, the ID of E. coli was more than two times higher (0.33 vs. 0.72) when increasing the pressure of air flow was applied from 1 to 2 bar. Finally, the ventilation air flow also affected the distribution of bioaerosols due to its direct relationship with the relative humidity of indoor air. Specifically, the airborne bacteria concentration diminished almost below 3-logs by applying more than 10 L min−1 during the aerosolization of urine due to their inactivation by an increase in their osmotic pressure.

Bioaerosol distribution characteristics and potential SARS-CoV-2 infection risk in a multi-compartment dental clinic

Dental clinics have a potential risk of infection, particularly during the COVID-19 pandemic. Multi-compartment dental clinics are widely used in general hospitals and independent clinics. This study utilised computational fluid dynamics to investigate the bioaerosol distribution characteristics in a multi-compartment dental clinic through spatiotemporal distribution, working area time-varying concentrations, and key surface deposition. The infection probability of SARS-CoV-2 for the dental staff and patients was calculated using the Wells–Riley model. In addition, the accuracy of the numerical model was verified by field measurements of aerosol concentrations performed during a clinical ultrasonic scaling procedure. The results showed that bioaerosols were mainly distributed in the compartments where the patients were treated. The average infection probability was 3.8% for dental staff. The average deposition number per unit area of the treatment chair and table are 28729 pcs/m2 and 7945 pcs/m2, respectively, which creates a possible contact transmission risk. Moreover, there was a certain cross-infection risk in adjacent compartments, and the average infection probability for patients was 0.84%. The bioaerosol concentrations of the working area in each compartment 30 min post-treatment were reduced to 0.07% of those during treatment, and the infection probability was <0.05%. The results will contribute to an in-depth understanding of the infection risk in multi-compartment dental clinics, forming feasible suggestions for management to efficiently support epidemic prevention and control in dental clinics.

Effect of environmental factors on the concentration distribution of bioaerosols with different particle sizes in an enclosed space

COVID-19 has alerted us about the need to quantify the effect of different environmental factors on the concentration distribution of bioaerosols. An experimental investigation was carried out to evaluate the effect of environmental factors, including air temperature, relative humidity, airflow speed and ultraviolet (UV) radiation, on the potential dispersion risk of bioaerosols in an enclosed space by tracking the Serratia marcescens as the tiny organisms. Research results indicated that the concentration of bioaerosols is the highest at the indoor air temperature of 25°C among the tested conditions (20°C, 25°C, 30°C and 35°C). The particle size of bioaerosols can be influenced by temperature, resulting in changes in the amount of settling. Increasing relative humidity from 50% to 80% and airflow speed from 1.5 m/s to 2.2 m/s have a negative impact on the dispersion of bioaerosols as the amount of particle settlement increases accordingly. As for the UV radiation parameters, a better disinfection efficiency was achieved at a radiation distance of 40 cm in the tested range of 20–50 cm and a radiation exposure time of 30 min in the tested range of 10–50 min. This study delivered novel data for the concentration distribution of bioaerosol under different environmental factors for creating a safe indoor environment.

How effective are face coverings in reducing transmission of COVID-19?

In the COVID-19 pandemic, among the more controversial issues is the use of face coverings. To address this we show that the underlying physics ensures particles with diameters & 1 $\mu$m are efficiently filtered out by a simple cotton or surgical mask. For particles in the submicron range the efficiency depends on the material properties of the masks, though generally the filtration efficiency in this regime varies between 30 to 60 % and multi-layered cotton masks are expected to be comparable to surgical masks. Respiratory droplets are conventionally divided into coarse droplets (> 5-10 $\mu$m) responsible for droplet transmission and aerosols (< 5-10 $\mu$m) responsible for airborne transmission. Masks are thus expected to be highly effective at preventing droplet transmission, with their effectiveness limited only by the mask fit, compliance and appropriate usage. By contrast, knowledge of the size distribution of bioaerosols and the likelihood that they contain virus is essential to understanding their effectiveness in preventing airborne transmission. We argue from literature data on SARS-CoV-2 viral loads that the finest aerosols (< 1 $\mu$m) are unlikely to contain even a single virion in the majority of cases; we thus expect masks to be effective at reducing the risk of airborne transmission in most settings.

Why should we care about high temporal resolution monitoring of bioaerosols in ambient air?

This is the first time that atmospheric concentrations of individual pollen types have been recorded by an automatic sampler with 1-hour and sub-hourly resolution (i.e. 1-minute and 1-second data). The data were collected by traditional Hirst type methods and state-of the art Rapid-E real-time bioaerosol detector. Airborne pollen data from 7 taxa, i.e. Acer negundo, Ambrosia, Broussonetia papyrifera, Cupressales (Taxaceae and Cupressaceae families), Platanus, Salix and Ulmus, were collected during the 2019 pollen season in Novi Sad, Serbia. Pollen data with daily, hourly and sub-hourly temporal resolution were analysed in terms of their temporal variability. The impact of turbulence kinetic energy (TKE) on pollen cloud homogeneity was investigated. Variations in Seasonal Pollen Integrals produced by Hirst and Rapid-E show that scaling factors are required to make data comparable. Daily average and hourly measurements recorded by the Rapid-E and Hirst were highly correlated and so examining Rapid-E measurements with sub-hourly resolution is assumed meaningful from the perspective of identification accuracy. Sub-hourly data provided an insight into the heterogenous nature of pollen in the air, with distinct peaks lasting ~5–10 min, and mostly single pollen grains recorded per second. Short term variations in 1-minute pollen concentrations could not be wholly explained by TKE. The new generation of automatic devices has the potential to increase our understanding of the distribution of bioaerosols in the air, provide insights into biological processes such as pollen release and dispersal mechanisms, and have the potential for us to conduct investigations into dose-response relationships and personal exposure to aeroallergens.

Distribution of Bioaerosols in Association With Particulate Matter: A Review on Emerging Public Health Threat in Asian Megacities

Occurrences and exposure to high levels of microbial bioaerosols such as pathogenic bacteria, fungi, fungal spores, and viruses can be linked to the deterioration of the environment and public health. This study aimed to review the results available for the unusual bioaerosol distribution scenario in the Asian regions. The amount of bioaerosol load and their environmental behavior in the atmosphere is heavily influenced by air pollution such as haze, fog, dust, and particulate matter (PM) and thus strongly affect the air quality index (AQI). Human factors such as heavy traffic, overcrowds, and biomass burning also affected the prevalence or occurrences of bioaerosols in the atmosphere. Seasonal/temporal and diurnal variation was significantly observed from these studies and in the case of South Asia, post-monsoon and winter months were incredibly concentrated with pathogenic bioaerosols. Many human infections, for example, pneumonia, tuberculosis, brucellosis, anthrax, and query fever (Q-fever), are linked to pathogenic bacterial bioaerosols. Respiratory diseases such as asthma and chronic pulmonary obstructiveness are related to fungal bioaerosols, spores, and viral infections. To facilitate the testing and monitoring appraisal of airborne bioaerosols, artificial intelligence, deep neural networks, and machine learning can be used to develop real-time PCR-based bioaerosol sensors. Moreover, mobile apps and compatible electronic gadgets can be developed for the city dwellers to real-time monitor the concentration of bioaerosols in the air they are breathing.