I have studied the nature and formation of sandstorms
I have seen severe sand storms with 6kts of wind, and airports going from CAVOK to 50 meters in minutes, so i think that the best advise is to avoid them like the plague.
A Pprune search will show a discussion on a BBJ (737-400) that suffered a DOUBLE engine failure during takeoff, the managed to restart at least one engine and returned for landing, this was following a severe sandstorm, its interesting to note that this same aircraft now has condom style engine covers!
Mutt