The Portuguese Society of Allergology and Clinical Immunology (SPAIC) forecasts very high concentrations of pollen in the atmosphere until Thursday for all regions of mainland Portugal, moderate levels for the Azores and low in Madeira. According to the pollen bulletin prepared by SPAIC, the pollen present in the air comes mainly from holm oak, cypress and plane trees, nettles and grasses. In the interior regions of the country and in the Algarve, pollens from grasses and plantain are beginning to appear in the air and gradually gain importance, while in the North, the concentrations are of birch pollen.