After my recent visit to the USA, I returned to this scene in my apartment:
Turns out I had shut the window, but not latched it closed. They had some strong winds while I was away, combined with the "yellow storms" and plain old rain. You can see the line of dust left by the yellow wind. Not visible are the small warped bumps on my sofa arm (it is wooden and contains a small drawer). That'll teach me.
While I am not a good housekeeper, and don't dust and vacuum often enough, I can assure you that this dust photo is indeed yellow wind from China, and NOT the result of my poor cleaning.