Nice photos of a turbine blade.
So air flows through those holes and comes out the other end.
So dust is light enough to float in the air at very high altitudes and manages to flow into the cooling channels and out the other end.
Too much dust and problems begin to develop oh so slowly at first.
It's a good thing that too much of a bad thing doesn't occur very often.
Now if we could only get birds down to the size of dust specs.
It's the melting of the dust and replating that's the problem, but fortunately that's pretty rare if you manage your flight path around the worst of the clouds.