Pollen falling... forever?

I just completed building a honey farm, at y=85. Beneath it is some dirt and rock and then my storage area at y=61. After building the honey farm I noticed pollen particles falling through my storage area. Hmmm... that's odd, but ok. Beneath that is a work area, y=48. I noticed pollen still falling through the room. This is a total of 37 levels including more than 10 levels of solid blocks broken into at least 3 separate groups.

How far is pollen supposed to travel?