Aerobiology

Global environmental change is rapidly altering the dynamics of terrestrial vegetation, with consequences for the functioning of the Earth system. Recent studies show that climate change is influencing the phenology and distribution of plants. Airborne pollen reflects the flowering period of the plant, which is influenced by meteorological variables such as temperature and rainfall. The analysis of pollen trends is a very useful tool for understanding the effects of climate change on vegetation. In fact, it is accepted that the onset and peak abundance of certain pollen types should be used as possible bioindicators of climate change. The aim of the work is to analyze the presence of various pollen in Rome—from their release from the anthers to their permanence in the atmosphere, the trends of phenological (start, length, and end of the pollen season) and production (pollen abundance and pollen peaks) pollen indicators, the trends of the meteorological variables mainly involved (temperature and precipitation), and any relationships between pollen and meteorological variables, also based on the variation in vegetation. In the period considered, the analysis of the pollen spectra shows an increasing trend in herbaceous taxa, probably attributed to a gradual abandonment of farming practices in the neighboring area, which in recent years has been the subject of intense new construction activity and to a progressive deterioration in the maintenance of green areas. Full article

This paper addresses the study of synoptic-scale meteorological conditions that favor long-range pollen transport in southern South America combining airborne pollen counts, modeled three-dimensional backward trajectories, and synoptic and surface meteorological data. Alnus pollen transport trajectories indicate origins predominantly in montane forests of the Yungas between 1500 and 2800 m altitude. The South American Low-Level Jet is the main meteorological feature that explains 64% of the detected pollen arrival at the target site. Podocarpus and Nothofagus pollen instead are linked primarily to the widespread Subantartic forests in southern Patagonia. Their transport patterns are consistent with previous studies, which show an association with synoptic patterns related to cold front passages carrying pollen in the free atmosphere (27% for Nothofagus and 25% for Podocarpus). These results show the significance of understanding long-distance pollen transport for disciplines such as climate change reconstruction and agriculture, emphasizing the need for further research to refine atmospheric circulation models and refine interpretations of past vegetation and climate dynamics. Full article

Bioaerosols constitute a crucial component of atmospheric particulate matter, encompassing physical and chemical aerosol properties along with biological characteristics. They can influence global ecosystems, climate change dynamics, and air quality. Notably, bioaerosols serve as a significant pathway for transmitting respiratory infectious diseases, garnering widespread attention worldwide following major pandemics such as COVID-19. Thanks to the development of high-throughput sequencing technologies, studies on bioaerosols have flourished in recent years. Understanding the interconnectedness of sources, spatial and temporal distributions, influencing factors, and health risks associated with bioaerosols is imperative for devising pollution mitigation strategies and preventing the spread of related epidemics. This review provides an overview of bioaerosol sources while elucidating distribution patterns within their community structure across various source types. Lastly, this overview offers insights into future advancements in the field of bioaerosols along with corresponding recommendations. Full article

The role that aquatic aerosols might play in inter-ecosystem exchanges in freshwater riparian environments has largely been understudied. In these environments, where freshwater streams are used both as drinking water and for treated waste disposal, water features like waterfalls, downed trees, and increased streamflow can serve as bioaerosol producers. Such water features could have an important role in the bacterial colonization of surrounding surfaces, including the riparian phyllosphere. In this study, we explore the influence of a freshwater stream’s bacterial community composition and micropollution on riparian maple leaves exposed to bioaerosols produced from that stream. Using culture-based and non-culture-based techniques, we compared phylloplane microbial communities in riparian zones, adjacent non-riparian forested zones, and the surface waters of the stream. In this system, riparian zone maple leaf surfaces had higher bacterial counts than non-riparian zone trees. Using metagenomic profiling of the 16S rRNA gene, we found that, while microbial communities on leaves in both the riparian zone and forested sites were diverse, riparian zone bacterial communities were significantly more diverse. In addition, we found that riparian leaf bacterial communities shared more amplicon sequence variants (ASVs) with stream bacterial communities than forest leaves, indicating that the riparian zone phyllosphere is likely influenced by bioaerosols produced from water surfaces. Full article

This study aims to investigate the seasonal variation and source identification of fluorescent aerosol particles at the monitoring site of the University of Salento in Lecce, southeastern Italy. Utilizing a wideband integrated bioaerosol sensor (WIBS), this research work analyzes data from two specific monitoring days: one in winter (10 January 2024), marked by significant transport of anthropogenic particles from Eastern Europe, and another in early spring (6 March 2024), characterized by marine aerosol sources and occasional desert dust. This study focuses on the seven WIBS particle categories (A, B, C, AB, AC, BC, ABC), which exhibited distinct characteristics between the two days, indicating different aerosol compositions. Winter measurements revealed a predominance of fine-mode particles, particularly soot and bacteria. In contrast, spring measurements showed larger particles, including fungal spores, pollen fragments, and mineral dust. Fluorescence intensity data further emphasized an increase in biological and organic airborne material in early spring. These results highlight the dynamic nature of fluorescent aerosol sources in the Mediterranean region and the necessity of continuous monitoring for air quality assessments. By integrating WIBS measurements with air mass back-trajectories, this study effectively identifies fluorescent aerosol sources and their seasonal impacts, offering valuable insights into the environmental and health implications of aerosol variability in the investigated Mediterranean area. Full article

Indoor microclimate conditions and air pollutant concentrations (O₃, TVOC, CO, CO₂, and particulate matter mass concentrations in six size bins) were measured in the Greek Archaeological Museum of Abdera, which houses priceless works of art from the birthplace of the ancient philosopher Democritus. The monitoring campaign took place during the spring and summer months, when there were the greatest number of visitors. In the exhibition rooms, daily variations in relative humidity ranged from 4% to 10%, and daily variations in air temperature ranged from 0.9 °C to 2.6 °C. These uncontrolled changes may endanger the housed antiquities. The microclimate in the storage rooms varied substantially less than in the exhibition halls due to dehumidifiers and the lack of visitors. Concerning air pollution, indoor O₃ concentrations were higher than the recommended limit values for the conservation of artwork. Even more worrisome are particulate matter mass concentrations above the air quality guidelines. Despite the fact that the building is well insulated and that only artificial lighting is used in the exhibition halls, it is difficult to achieve adequate conditions for the protection of the works of art. Full article

Our study aimed to quantify the pollen trapped by the seeds and relate it with the airborne pollen concentrations. Individual Populus spp. tuft-like seeds were sampled while suspended twice a day in 2017 and 2018 during the seed dispersal season. The seeds were submitted to laboratory treatment for pollen extraction, which was quantified using an optical microscope. Airborne pollen was monitored using a seven-day Hirst-type volumetric spore sampler. A correlation analysis was performed between the airborne pollen, the pollen on the seeds, and the meteorological parameters. A total of 26 pollen grains/mg was counted in the airborne tuft-like seeds, with 26 different taxa being identified, compared with the 18 pollen taxa identified in the airborne samples. Quercus, Poaceae, Urticaceae, Pinus, and Platanus were the most frequent pollen found on the seeds, while in the atmosphere, pollen from Urticaceae, Quercus, and Cupressaceae were the most representative. A tendency of higher pollen concentrations found in the afternoon samples, both airborne and on the seeds, was observed. Correlations between the meteorological parameters and pollen concentration found airborne and in the seeds were overall not significant. Thus, airborne poplar tuft-like seeds can trap and transport pollen, most of which has been recognized to induce respiratory allergies. Full article

About 40% of cedar pollinosis patients living in the Yamagata Prefecture showed pollinosis symptoms before the first day of the pollen season, which was determined by Durham samplers, the standard sampler for pollen information in Japan. The amount of Cry j 1 (major cedar pollen allergen) per cedar pollen is reported to be six pg. This amount is difficult to measure using the ELISA method, so we applied the highly sensitive ESR radical immunoassay method to measure the allergen; now we can provide information for sensitive patients. It revealed that Cry j 1 exists in orbicles and tapetum. It is presumed that it is smaller than pollen, so it comes from a place where cedar are already in bloom. It is desirable to obtain real-time information on an hourly basis. Currently, information from automatic cedar pollen monitors is becoming main-stream. However, this monitor may count during snowfalls, Asian dust flying, etc., even when there was no apparent pollen examined with a microscope. This paper describes the current status of automatic cedar pollen monitors, their usefulness, and their advantages and disadvantages in comparison with results obtained by other methods of measurement. Lastly, the paper describes expectations for cedar pollen information in the future. Full article

Although studies focusing on the physicochemical properties of aerosols/clouds have not been performed extensively, even less attention has been given to hailstones and their biological composition. Here, we present the results of the physical and microbiological characterisation of 20 hailstones collected in Southern Brazil originating from two storms. Nearly half of the hailstones (9 out of 20, or 45%) did not contain any cultivable bacteria or fungi. A total of 18 bacterial species were found in hailstones from both storms, and the genus Bacillus was found in 5 out of the 11 hailstones, with Bacillus cereus being the most frequent bacterial species. Fungi, on the other hand, were only present in four hailstones derived from a single storm, with three fungal species identified and Epicoccum nigrum being the most frequent fungal species. HYSPLIT modelling indicated the different flow of air masses from the Amazon and Pacific Ocean that contributed to the loading of microorganisms found in the clouds at the time of the two storms. Our findings suggest that ca. 50% of hailstones have cultivable bacterial or fungal species, which came mainly from the local landscape with intrusions of air masses derived from the Amazon and the Pacific Ocean. Full article

UV irradiation has shown potential in reducing bacterial and viral loadings. This is a pilot study aimed at investigating the antimicrobial effect of a novel pulsed UVA and UVC technology on bacteria and human coronavirus 229E. The selection of these microorganisms is based on their relevance and significance in real-world scenarios. This study consists of independent experiments for the assessment of antibacterial and antiviral activities by using a lawn plate approach, measuring levels of adenine triphosphate (ATP) in three bacterial strains, Escherichia coli, Staphylococcus epidermidis and Bacillus subtilis, and performing Median Tissue Culture Infectious Dose (TCID₅₀) of HCoV-229E on MRC-5 human lung fibroblast cell line. The results demonstrated the ability of UVA and UVC irradiation to reduce levels of adenine triphosphate (ATP) over a 12 h exposure period in all three bacterial strains, comparative to dark and artificial/natural light conditions using non-pulsing experiments. In addition to this, there was a reduction in colonies exposed to UVA and UVC pulsing experiments for E. coli K12 and S. epidermis compared to bacteria stored in artificial/natural and dark conditions. Furthermore, using dose-dependent modelling, it was demonstrated that the cross-contamination risk was reduced by 50% using E. coli as a typical model. Regarding the antiviral assay, the results showed that TCID₅₀ of HCoV-229E was reduced after the first cycle of UV engagement. No cytopathic effect (CPE) was detected after three cycles using Protocol 1. The findings showed that UVA and UVC were effective under the conditions outlined in this paper for a reduction in the number of bacteria with additional applications to viruses. Full article

Avian influenza virus (AIV) can have a serious impact on both human and animal health. In this study, we used an environmentally controlled chamber and a hemagglutination assay (HA) to evaluate the ability of membrane-less electrolyzed water (MLEW) spraying to inactivate H6N1 AIV aerosol. MLEW was generated by electrolyzing sodium chloride solution, and then sprayed into the chamber at free available chlorine (FAC) concentrations of 50, 100 and 200 mg/L by means of high-pressure air pumping to inactivate airborne H6N1 AIV aerosols individually. The results showed that MLEW spraying effectively neutralized H6N1 AIV aerosol. In addition, the virucidal ability of MLEW increased as the FAC concentration increased. Five minutes after MLEW spraying at an FAC concentration of 200 mg/L, the H6N1 viral HA titer decreased from 2⁴ to 2⁰. Our work provides important new evidence of the value of spraying with MLEW disinfectant to protect against AIV, which may be further applied for indoor decontamination purposes to promote animal and human health. Full article

Allergic diseases are a global health problem; their prevalence has increased in recent decades. The presence of allergenic airborne pollen is one of the main triggers of this disorder. For this reason, the first pollen calendar of Toluca City was developed. Daily and bihourly airborne pollen samplings with a Hirst-type Burkard Trap were performed from August 2009 to December 2013. Annual Pollen Integral (APIn), Main Pollen Season (MPS) and Diurnal Pattern (DP) were determined. Relationships with meteorological parameters were investigated. Tree pollen grain presented higher concentrations, with Cupressaceae as the most abundant taxon (52.6%), followed by Alnus sp. (13.3%), Pinaceae (7.3%), Fraxinus sp. (6.0%) and Quercus sp. (2.0%), which presented a definite seasonality. Urticaceae (3.7%) was the most abundant herbaceous pollen taxon registered. The DP obtained showed that pollen grains of most taxa are frequently found after midday and afternoon. Regression models showed the influence of environmental variables on all taxa. This study will allow us the enhancement of preventive actions and improvement of the regional design of patient tests. Full article

Background: It has been recognized from the early days of allergology that aerobiological investigations have an important role to play in the development of respiratory allergic diseases. An increasing number of allergic complaints occurred among the atopic population during the blooming season of Kans grass, Saccharum spontaneum (SS), an obnoxious weed growing in and around suburban West Bengal. The present study aimed to identify SS pollen as a potential aero allergen through aerobiological, clinical, statistical, and biochemical analyses. Methods: An aerobiological survey was conducted for 2 years followed by a clinical diagnosis of 134 local atopic patients suffering from a respiratory allergy by a standard questionnaire survey and the skin prick test (SPT) using SS antigens. The antigenic protein profile was analyzed by SDS-PAGE and the allergizing potential of this pollen was investigated by an in vitro enzyme-linked immunosorbent assay to recognize the presence of the sero-reactive proteins which were the suspected cause of the respiratory allergy. A Box-plot and regression analysis were performed to establish the significance of clinical data. Results: SS pollen was found to evoke about 70.14% sensitivity among the atopic population causing early spring hay fever, allergic rhinitis, and seasonal allergic conjunctivitis. A regression analysis for the pollen antigen for estimating the total IgE value of a patient’s sera from their specific IgE value was a novel approach by our study. The antigenic extract of pollen resolved into more than 15 distinct protein bands ranging from 14.4 to 116 kDa, some of which were found to be glycosylated. The results showed that SS pollen has a significant presence in the atmosphere, which may trigger an allergic response in immunocompromised patients. Conclusions: This is, to our knowledge, the first attempt to identify allergens from Kans pollen causing seasonal pollinosis among the Indian atopic population using an immuno-clinical approach. Full article

Over 1 million Syrian refugees have fled war to seek asylum in Lebanon. The population has been placed in substandard conditions which could lead to adverse health effects, particularly in vulnerable subgroups, notably due to evident chronic dampness and inadequate ventilation potentially leading to indoor mold growth. To investigate whether the types and conditions of Syrian refugee shelters influence indoor mold populations, a cross-sectional indoor environmental study was performed in 4 provinces of Lebanon. Accordingly, a total of 80 refugee households and 20 host population households (baseline) were selected. Mold air sampling and moisture measurements of shelter material were performed in residential, non-residential, and non-permanent shelters. Results revealed that although non-residential shelters had the highest mean total indoor count (1112 CFU/m³), Aspergillus, Stachybotrys, and Penicillium spp. were strongly associated with non-permanent shelters (p < 0.001). Additionally, occupancy was found to be strongly associated with Cladosporium (p < 0.05), Ulocladium (p < 0.05), and Stachybotrys spp. (p < 0.001). As for shelter conditions, the highest total indoor count (1243 CFU/m³) was reported in unfinished structures. These findings suggest that shelter category, condition and occupancy significantly influence indoor mold concentrations, increasing respiratory health risks for Syrian refugees in Lebanon. Full article

Introduction-Aims: Fungi are ubiquitous microorganisms that are easily dispersed through the air. In healthcare environments, indoor air can favor the spread of healthcare-associated fungal infections, compromising mainly immunocompromised hospitalized individuals. Therefore, this study aimed to evaluate indoor air contamination in healthcare environments, investigating mainly the presence of potentially pathogenic yeasts. Method: Indoor air samples were collected from 12 healthcare environments (hospital and medical clinics). After the growth, isolation, and purification of the yeast colonies, the isolates were identified by polymerase chain reaction using species-specific primers for yeasts of the genus Candida and sequencing of D1/D2 domains of the large ribosomal subunit (LSU rRNA). Results and interpretation: Fourteen yeast species were identified, including emerging pathogens. Species of clinical importance such as Candida parapsilosis, Candida glabrata, and Rhodotorula mucilaginosa were present. C. parapsilosis was the most prevalent species, followed by Rhodotorula mucilaginosa. In addition, we report the first occurrence of Candida orthopsilosis, Trichosporon mucoides, Fereydounia khargensis, and Hortaea werneckii in indoor air samples collected in healthcare environments. The present study shows that potentially fungal pathogens were present in air samples from healthcare environments, proving the role of indoor air in spreading infections. Therefore, monitoring air quality in healthcare environments is a fundamental approach to developing infection control measures, especially those related to invasive fungal infections. Full article