Alternaria spores are pathogenic to agricultural crops, and the longest and the most severe sporulation seasons are predominantly
recorded in rural areas, e.g. the Pannonian Plain (PP) in South-Central Europe. In Poland (Central Europe),
airborne Alternaria spore concentrations peak between July and August. In this study, we test the hypothesis that the
PP is the source of Alternaria spores recorded in Poland after the main sporulation season (September–October).
Airborne Alternaria spores (2005–2019)were collected using volumetric Hirst spore traps located in 38 locations along
the potential pathways of air masses, i.e. from Serbia, Romania and Hungary, through the Czech Republic, Slovakia
and Ukraine, to Northern Poland. Three potential episodes of Long Distance Transport (LDT) were selected and characterized
in detail, including the analysis of Alternaria spore data, back trajectory analysis, dispersal modelling, and description
of local weather and mesoscale synoptic conditions.
During selected episodes, increases in Alternaria spore concentrations in Poznań were recorded at unusual times that
deviated from the typical diurnal pattern, i.e. at night or during morning hours. Alternaria spore concentrations on
the PP were very high (>1000 spores/m3) at that time. The presence of non-local Ambrosia pollen, common to the
PP, were also observed in the air. Air mass trajectory analysis and dispersal modelling showed that the northwest
part of the PP, north of the Transdanubian Mountains, was the potential source area of Alternaria spores.
Our results show that Alternaria spores are transported over long distances from the PP to Poland. These spores may
markedly increase local exposure to Alternaria spores in the receptor area and pose a risk to both human and plant
health. Alternaria spores followed the same atmospheric route as previously described LDT ragweed pollen, revealing
the existence of an atmospheric super highway that transports bioaerosols from the south to the north of Europe.