THE INJURED WORKER HAD JUST FINISHED MOVING THE CLINKER CONVEYOR TRIPPER AND WAS DESCENDING A SHORT LADDER TO THE CATWALK BELOW WHEN RAIN STARTED TO FALL ON THE ROOF CAUSING DUST THAT HAD SETT LED ON HORIZONTAL SURFACES TO SHAKE LOOSE. HE LOOKED UP AS HE HEARD THE RAIN HIT THE ROOF. AT THAT MOMENT DUST FELL AND HIT HIS FOREHEAD JUST ABOVE HIS SAFETY GLASSES. DUST GOT INTO HIS EYE.