Brussels High amounts of spores of meadow and wood mushrooms (Basidomycetes) are present in the air. Persons allergic to the fungal spores of the genus Cladosporium should stay careful as these spores are still present in the air. Follow us too on Twitter @AirAllergy ! Good to know Indiviual sensitivity may vary a lot. It is reported in literature that 3000 spores of Cladosporium per m³ are enough to induce allergy symptoms to sensitized persons.