EE WAS TAKING DOWN STAIR SCAFFOLDING. EE WAS LOWERING SCAFFOLD SECTION BY ROPE TO EE'S BELOW. ONE PIECE GOT HUNG UP ON SCAFFOLD BELOW, APPROX 4' ABOVE GROUND. EE PICKED UP THE PIECE TO FREE IT WHEN THE EE ON TOP STARTED TO LOWER THE PIECE, THE SCAFFOLDING PRESSED DOWN AND PINCHED THE EE'S THUMB.