The pollen season has now begun for the early pollen producers, writes the National Museum of Natural History in its pollen report.
It is hazel that has started to bloom in Götaland and southern Svealand, and in the Jönköping region, in Skåne and Blekinge alder is blooming.
Even up in Gävle, low levels of pollen have been discovered.
What many people are allergic to is birch pollen, which comes later in April, but if you are allergic to birch, you can also react to alder, according to Naturhistoriska.
Right now there is an "increased risk of high levels" of pollen in southern Sweden, which is the second highest level on the three-point scale that the museum uses.
As the weather gets warmer in the spring, the levels will continue to rise.
See more in the player above.