Pollen from birch trees was carried along with dust from the Sahara Desert on strong winds that originated in Eastern Europe.

As many allergy-sufferers across Finland may have already suspected, birch pollen levels were very high on Wednesday, according to the University of Turku.

Spiking levels of birch pollen around much of the state are also being seen during an early spring in Anchorage this week, as doctors deal with an influx of allergy and asthma patients.

Alder catkins (the pollen-rich flowers on alder trees) haven't reached their peak yet, but there are a lot of them. There can be four to five million pollen particles in a single catkin.