Investigation of Sources, Diversity, and Variability of Bacterial Aerosols in Athens, Greece: A Pilot Study

We characterized the composition, diversity, and potential bacterial aerosol sources in Athens’ urban air by DNA barcoding (analysis of 16S rRNA genes) during three seasons in 2019. Air samples were collected using the recently developed Rutgers Electrostatic Passive Sampler (REPS). It is the first field application of REPS to study bacterial aerosol diversity. REPS samplers captured a sufficient amount of biological material to demonstrate the diversity of airborne bacteria and their variability over time. Overall, in the air of Athens, we detected 793 operational taxonomic units (OTUs), which were fully classified into the six distinct taxonomic categories (Phylum, Class, Order, etc.). These OTUs belonged to Phyla Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Fusobacteria. We found a complex community of bacterial aerosols with several opportunistic or potential pathogens in Athens’ urban air. Referring to the available literature, we discuss the likely sources of observed airborne bacteria, including soil, plants, animals, and humans. Our results on bacterial diversity are comparable to earlier studies, even though the sampling sites are different or geographically distant. However, the exact functional and ecological role of bioaerosols and, even more importantly, their impact on public health and the ecosystem requires further air monitoring and analysis.

The influence factors of mean particle size and positive quality control of bacterial filtration efficiency system

Summary Background The Coronavirus Disease 2019 (COVID-19) has swept the whole world with high mortality. Since aerosol transmission is the main route of transmission, wearing a mask serves as a crucial preventive measure. An important parameter to evaluate the performance of a mask is the bacteria filtration efficiency (BFE). Aerosol mean particle size (MPS) and positive quality control value are two key indexes of BFE system. Aim To study the major influence factors of the mean particle size of bacterial aerosols and positive quality control value of BFE system. Method and Results In this study, we investigated the influence of Anderson sampler, spray flow, medium thickness, and peristaltic pump flow on the MPS of bacterial aerosols and positive quality control value of BFE system, respectively. The results show that the machining accuracy of Anderson sampler has great influence on aerosol MPS and positive quality control value. With the increase of aerosol spray flow rate, the positive quality control value will increase gradually, but the effect on aerosol MPS is not a simple linear relationship. As the agar medium thickness increased, the positive quality control value and aerosol MPS increased gradually. With the increase of peristaltic pump flow, the positive quality control value increased gradually, while the aerosol MPS was basically in a downward trend. When the peristatic pump flow rate was 0.1mL/min, the spray flow rate was 7.2L/min, the agar plate thickness was 27mL, and the Anderson sampler of Beijing Mingjie was used for the experiment, the aerosol MPS and positive quality control value were both within the acceptable range and were the optimal parameters. Conclusions This study provides guidance for the manufacturers of the BFE system and improves the protective performance of masks, which is important for the human health, especially during the occurrence of viral pandemics such as "COVID-19".

The Association between the Concentration of Heavy Metals in the Indoor Atmosphere and Atopic Dermatitis Symptoms in Children Aged between 4 and 13 Years: A Pilot Study

Background: A correlation between the harmful effects of air pollutants and atopic dermatitis has been reported. There are few studies on the correlation between the concentration of heavy metals in the indoor atmosphere and symptoms of atopic dermatitis. Methods: Twenty-two homes of children showing atopic dermatitis symptoms were enrolled, and eighteen homes with similarly aged children without symptoms or a history of atopic dermatitis participated as a control group. We measured the concentrations of various air pollutants (particulate matter 10, carbon dioxide, carbon monoxide, formaldehyde, nitrogen dioxide, volatile organic compounds (VOCs), ozone, radon, bacterial aerosols, and mold) as well as various heavy metals, such as lead, cadmium, and mercury, in the living room and children’s bedroom of each home. Results: Lead was more commonly detected in the indoor air in houses of children with atopic dermatitis (15/22) as compared to in the control group (3/18) (chi square test, p = 0.002). In adjusted logistic regression analysis, VOCs and lead were significantly associated with atopic dermatitis (p < 0.05). Conclusion: Our study shows that lead in indoor air might be associated with atopic dermatitis, even if the concentrations of airborne lead are below the safety levels suggested by health guidelines.

Efficiency of Air Purifiers at Removing Air Pollutants in Educational Facilities: A Preliminary Study

Infectious diseases caused by airborne bacteria and viruses are a major problem for both social and economic reasons. The significance of this phenomenon is particularly noticeable during the time of the coronavirus pandemic. One of the consequences is the increased interest in the air purifier (AP) market, which resulted in a significant increase in sales of these devices. In this study, we tested the efficiency of APs in removing bacterial air contamination in the educational context in the Upper Silesia region of Poland during the “cold season” of 2018/2019. During the 6 months of measuring microbiological air quality, an 18% decrease in the concentration of microbiological pollutants as a result of the action of the APs was recorded. Additionally, the results of the particle size distribution of the bacterial aerosols showed a reduction in the share of the respirable fraction (particles with an aerodynamic diameter below 3.3 µm) by an average of 20%. The dominance of gram-positive cocci in the indoor environment indicates that humans are the main source of most of the bacteria present in the building. We conclude that the use of APs may significantly decrease the level of concentration of microbiological air pollutants and reduce the negative health effects of indoor bioaerosols; however, further work that documents this phenomenon is needed.

Physical collection and viability of airborne bacteria collected under electrostatic field with different sampling media and protocols towards rapid detection

Electrostatic samplers have been increasingly studied for sampling of viral and bacterial aerosols, and bioaerosol samplers are required to provide concentrated liquid samples with high physical collection and biological recovery, which would be critical for rapid detection. Here, the effects of sampling media and protocols on the physical collection and biological recovery of two airborne bacteria (Pseudomonas fluorescens and Micrococcus luteus) under electrostatic field were investigated using a personal electrostatic particle concentrator (EPC). Deionized (DI) water with/without sodium dodecyl sulfate (SDS) and phosphate buffered saline were tested as sampling media. A polystyrene container was mounted onto the collection electrode of the EPC for stable storage and vortexing after capture. Many bacterial cells were found to be deposited on the bottom surface of the container submerged in the media via electrophoresis, and among the tested sampling protocols, wet sampling with a container and subsequent vortexing offered the most bacteria in the collection suspension. Experiments with several sampling media showed that 0.001–0.01% SDS-DI water demonstrated the highest recovery rate in the EPC. These findings would be valuable in the field of sampling and subsequent rapid detection of bioaerosols.

Investigation of sources, diversity, and variability of bacterial aerosols in Athens, Greece: a pilot study

This study is the first attempt to describe the composition, diversity, and potential sources of bacterial aerosols in the urban air of Athens by DNA barcoding (analysis of 16S rRNA genes). It is also the first field application of the recently developed Rutgers Electrostatic Passive Sampler (REPS) to study the microbial diversity of aerosols. Three sampling campaigns 6–10 days in duration were conducted in the summer and fall of 2019. The completely passive REPS captured a sufficient amount of biological material to demonstrate the diversity of airborne bacteria and their variability over time. Overall, in the air of Athens, 793 OTUs were detected. Firmicutes, Proteobacteria, and Actinobacteria were the dominant Phyla, while the Cyanobacteria, Bacteroidetes, and Fusobacteria were the minor Phyla. The observed Phyla were further classified into 54 families. The families with high prevalence across our samples contained genera known to have pathogenic species, e.g., Streptococcus, Corynebacterium, Gemella, Pseudomonas, Staphylococcus, Neisseria; many species belonging to human or animal commensal microbiota were also detected. The paper discusses the likely sources of observed airborne bacteria, including soil, plants, animals, humans. Given the variability in bacterial composition over time, it is obvious that the contribution of those sources to airborne microbiota is dynamic. However, a more accurate linkage between the sources and airborne bacteria requires further study. Also, the exact functional and ecological role and, even more importantly, the impact of observed bacterial aerosols on public health and the ecosystem is still unknown and required further analysis.

Spatial variation and comprehensive health risk assessment of microbial indoor air quality in microenvironments of North Delhi

The high airborne microbial concentration of indoor areas may be responsible for adverse indoor air quality linked with adverse respiratory and general health effects in the form of Sick building syndromes. The current study aimed to isolate and characterize seasonal (winter and spring) levels of culturable bio-aerosols from indoor air and their impact on human health by using an epidemiological health survey. After culturing, microorganisms were identified by standard macro and microbiological protocols followed by biochemical testing and molecular techniques. Sampling results show that bacterial aerosol concentration in the winter season varies from (300–3650 CFU/m) and fugal aerosols (300–4150 CFU/m3) in different microenvironments. However, in spring bacterial aerosols ranged (450–5150 CFU/m3) and fungi (350–5070 CFU/m3). Aspergillus and Cladosporium were major recorded fungi however, Staphylococcus, Streptobacillus, and Micrococcus were major bacterial genera among all the sites. Analysis of the questionnaire survey represented that headache (28%) and allergies (20%) were major indoor health problems followed by others. Major outcomes of the current study suggested that the elevated levels of bioaerosols are a major risk factor and causing various respiratory health problems. The observed dynamics of this study will help the inhabitants to take precautionary actions to avoid hazardous bioaerosols.