An emanator device for emanating an air treatment agent into the surrounding air comprises a housing (102) which contains a solid or liquid source of the air treatment agent, wherein the housing comprises a blister or capsule containing an air treatment agent (108) and a plurality of openings which are sufficiently small that they can be closed by a film or plug of water. For example the openings may be provided by a gauze or mesh (114). The openings do not inhibit the emanation of air treatment agent released from the blister, but when the emanator device is subject to wet conditions, as may happen in a dishwashing machine, the openings are blocked by a film or plug of water. The air treatment agent does not therefore enter the water, where it may have caused adverse effects, or simply have been wasted. Under dry conditions, however, emanation occurs normally.
