The tree pollen data is based on one of the most sensitising pollens in Italy, the olive tree, as well as the birch , oak and hazel . The grass data is based on the gramineae family of grasses while the weed pollen information is based on the urticaceae (nettles, pellitory) and compositae (specifically the burdock and thistles families.

The pollen data presented above is based on an average of the main pollens present in each of the following Italian regions throughout 1999 : Alpine Region; Po Valley Region; North Adriatic Region; North Tyrrhenian Region; South Adriatic Region; South Tyrrhenian Region; Southern and the Insular Region. For more precise data on pollen types and quantities in Italy, please contact the reference for this data. [ 1 ]