The pollen present in the air in the mainland regions comes essentially from olive, cork oak and oak trees and also from nettles, grasses, plantain and sorrel.

Forecasts up to May 18 indicate that in the regions of the Algarve, Alentejo, Lisbon and Setúbal the pollination of the chenopodium will predominate.

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 nearly the end of the month (in the central-north regions).

Every week, the pollen bulletin publishes the levels of pollen in the atmosphere, collected by reading posts in various regions of the country.