Nowadays, there is an increasing emphasis on the problem of invasive species. In areas where the tree of heaven (Ailanthus altissima) appears and multiplies, the original vegetation degrades and transforms.

The tree of heaven of great importance in urban environments, where it causes building damage, static problems and endangers utilities. In addition, it is worth mentioning that the pollen of Ailanthus altissima is an allergenic, although less important than ragweed pollen.

Pollen concentration of tree of heaven was measured in three counties of the Southern Great Plain region (Bács-Kiskun county, Csongrád-Csanád county, Békés county) with the 7-day Hirst-type (Burkard) pollen trap. The highest annual total pollen count was detected in 2018 in Bács-Kiskun county (131 pieces) and Csongrád-Csanád county (36 pieces), while in Békés county (16 pieces) in 2020. In Békés county, a trap error was detected when measuring the pollen count of A. altissima in 2019, therefore the results cannot be used.