Since 2009 the web based Patient’s Hay-fever Diary (PHD, www. pollendiary.com) has been used in ten European countries by over 25,000 users. PHD allows users to document their polleninduced symptoms of nose, eyes and bronchi, as well as their overall health, the medication used and their location. Regional pollen data supplied by the European Aeroallergen Network (https://ean.polleninfo.eu/Ean) allows analysis between pollen counts and pollen-induced symptoms. The correlation of pollen count data and pollen-induced symptoms enables determinations of personal threshold values for all major pollen species such as birch, grass and ragweed (i.e. the number of pollen grains recorded in the region that are needed to induce allergic symptoms). The severity of organspecific symptoms for the nose, eye and bronchi can be predicted using the combined results of PHD and a forecast for atmospheric concentrations of allergenic pollen. This personal pollen information (PPI) can then be sent to the user via a newly developed application (APP) for mobile devices. This will aid hay fever sufferers to avoid exposure to atmospheric concentrations of allergenic pollen and help them plan medication.