EE WAS USING PORTABLE GRINDER TO COMPLETE REPAIR TASKS ON TRUCK SCALE. EE WAS WEARING ALL REQUIRED EYE PROTECTION(S.GLASSES/FULL FACE SHIELD). WIND APPARENTLY WAS BLOWING AT EE'S BACK & AIRBOR NE MATERIAL WAS BLOWN INTO THE FACE SHIELD CAUSING A PIECE OF MATERIAL TO FLY INTO HIS EYE.