Intradiurnal variation of predominant airborne fungal spore biopollutants in the Central European urban environment

Fungal spores are an important cause of allergic respiratory diseases worldwide. However, little is known about the intradiurnal pattern of spore concentrations of different fungal spore types in the air of the urban area. In this study, we evaluated bihourly variation in spore concentration of eight predominant fungal spore types in the atmosphere of Bratislava city (Agrocybe, Alternaria, Cladosporium, Coprinus, Exosporium, Epicoccum, Ganoderma, Leptosphaeria) with the aim to understand the relationships between the spore concentrations against associated environmental variables. Spore samples were collected using a Hirst-type volumetric aerospore trap from January to December 2016. Alternaria, Cladosporium, Epicoccum and Exosporium peaked during the daytime period between 10:00 and 16:00, while for Agrocybe, Ganoderma, Coprinus and Leptosphaeria, the nighttime peaks (20:00 and 04:00) were observed. Effect of a complex of environmental variables on bihourly concentrations of selected airborne fungal spore taxa was evaluated through multiple regression analysis. Air temperature, wind speed, sunshine duration and precipitation were positively associated with daytime spore types, while the association with nighttime spores was negative. In contrast, relative air humidity influenced negatively Exosporium daytime spore type but positively the Leptosphaeria nighttime spore type. Moreover, a circadian cycle of light and darkness was considered as an important predictor of nighttime spore levels. Among the atmospheric pollutants, PM₁₀ was positively associated with all analysed daytime spores, while except for Leptosphaeria, O₃ was negatively associated with nighttime spore types. NO₂ and PM₁₀ had mixed effects on nighttime spore levels. In general, air temperature, PM₁₀ and wind speed were environmental parameters with great influence on airborne fungal spore concentration, being present in eight, seven and four regression models, respectively. Constructed regression models which the best explained variation in fungal spore concentrations were those for Ganoderma (R² = 0.38) and Alternaria (R² = 0.31).