WORKING ON DUST BOX HOSE ON LEFT SIDE OF CONT. MINER IN #3 ENTRY, 3 NORTH LEFT SECTION. A PIECE OF ROCK FELL FROM THE MINE ROOF AND KNOCKED VENT TUBE DOWN. TUBE STRUCK EE ON TOP OF RIGHT SHOULDER AND HE FELT PAIN IN LOWER BAC. THE INJURED CONT'D TO WORK UNTIL 3-16-04 WHEN HE STARTED MISSING WORK.