21.   Some of the mist spread outside the plant and to other rooms through an air duct that was directly below the leaking pipe.

22.   That wonderful green paint is found both on the trim work and door, and ornate brass grates are on the air ducts.

23.   The blast ripped down ceiling tiles, insulation and air ducts.

24.   The crew found no spores Tuesday in first-floor air ducts.

25.   The lighting is dim, the black-painted overhead air ducts are exposed, and the reception area is enclosed in high-tech metal mesh.

26.   The lanky prisoner, who was awaiting trial on eight burglary charges, apparently yanked a piece of wire from an air duct in his cell.

27.   The plastic air ducts are round aircraft style, which operate easily, though they feel flimsy.

28.   The roof of the pavilion contains a system of air ducts.

29.   Then they scrutinize the tape to make sure that every building air duct, door or hallway has been secured against possible assassins or bombers.

30.   There may be times when you will want to add or modify an air duct.