EMPLOYEE WAS REPAIRING LACING ON THE IMPACTOR BELLY BELT USING A DYE GRINDER; HE WAS WEARING SAFETY GLASSES AND A FACE SHIELD. THE WIND WAS BLOWING DUST, AND IT BLEW A PIECE OF ROCK OR SAND, IMBEDDING IT IN EMPLOYEE'S EYE JUST TO THE LEFT SIDE OF THE PUPIL.