Intact fungal spores and smaller fungal fragments such as hyphae are sources of airborne allergens. Information on the distribution of sub-spore allergenic particles in the atmosphere is however limited. Therefore, the main aim of this study was to explore the behaviour of Alternaria aeroallergens in the atmosphere of Ankara, central Turkey. Aerobiological monitoring was carried out in the 2020 season. A Burkard volumetric spore trap was used for fungal spore collection, and a high-volume cascade impactor for allergen collection. The Alt a 1 levels in two air fractions (particulate matter (PM) > 10 mu m and 10 > PM > 2.5 mu m) were measured by an enzyme-linked immunosorbent assay. The seasonal spore integral (SSIn) was 1846 spore day/m(3). In the same period, a total of 95.71 pg/m(3) Alt a 1 concentration was recorded, of which 93% was recorded in PM>10 and 7% in PM10-2.5 air fraction. The amount of allergen per spore was 5.18 x 10(-2) pg/spore/m(3). The highest concentration for both spores and allergens was observed on 30 June, i.e. before the local crop harvest. Four days with highest spore levels occurred about one week after the rainfall (> 1 mm). Hot and humid weather probably contributed to the intensive development of fungi and an increase in the concentration of spores in the atmosphere. Our findings suggest that in areas with semi-arid climate, such as central Turkey, the weather conditions have a greater effect on behaviour of the distribution of Alternaria aeroallergens than agricultural practices.