LEAD BLASTER IN CHARGE ON TOP OF TRUCK TO MONITOR FILLING OF STICK MAKING BIN. HE DIRECTED OPERATOR TO MOVE BOOM IN HIS DIRECTION. BOOM SWUNG RAPIDLY WITH INITIAL APPLICATION OF HYDRAULIC PRES SURE AND STRUCK BLASTER IN CHEST, KNOCKING HIM OFF THE TRUCK. BLASTER FELL 11 1/2' TO THE GROUND. HE SUFFERED BROKEN RIBS, PUNCTURED LUNG, BROKEN CLAVICLE, CUT TO BACK OF HEAD AND FOREHEAD.