A filter has been connected to an igloo at Blue Grass Army Depot where a mobile laboratory detected a low-level release of mustard vapor.
The Lexington Herald-Leader reports officials said the vapor detected Monday posed no danger to the public or the workforce on the installation near Richmond.
Mustard, or blister agent, is a powerful skin irritant. It's been stored at the site since 1944.
The filter is intended to ensure the vapor release is contained within the structure.
Blue Grass Chemical Activity, the agency that deals with chemical weapons at the depot, said the vapor was detected during a weekly routine analysis of the chemical weapons stockpile.
A work plan is being developed to allow trained chemical workers to determine the source of the vapor reading.