We'd get them every few years when I lived in the Saudi. Pretty harmless except the sand gets EVERYWHERE, and like mili mentioned it's a very powdery sand. It gets into your car, any crack in your door, your windows, your vents. Cleanup's a bitch. The other thing you can't tell from the video is how fast it's really coming. I remember playing soccer about a half mile from my house when one of these showed up on the horizon. We booked it back and barely made it in the house before it hit.