The society says that due to the possibility of rain over the next week, "the effect of "cleaning the atmosphere" may occur, temporarily reducing the concentration of pollen in the air".

Despite this, moderate to very high levels are expected for the mainland, with pollen predominating in the air, essentially from olive trees, cork oaks and oaks, and also from parietaria herbs, nettles, grasses, plantain and sorrel.

According to SPAIC, during the month of May there will be a very high concentration of atmospheric pollen from olive trees in mainland Portugal.

The pollen peak of this species has already started in the south-central regions and will last until near the end of the month in the central-north regions.