Population exposure to allergens has been increasing not only in Slovenia but also worldwide. This phenomenon is influenced by the increase in average air temperature. Higher average air temperature results in a longer growing season and thus the longer presence of allergenic pollen in the air. Particularly noteworthy is to mention the pollen of alder, birch, grasses and ambrosia. The severity of exposure to the allergen pollen of alder, birch, grasses and ambrosia shows large annual fluctuations, with distinct differences between the continental Slovenia and the littoral area.