Secret documents in the archives of the Privy Council Office are mould-infested – more than a decade after the pesky scourge was thought to have been killed off for good.
The mould first appeared in 2001, after a flood from a broken pipe drenched key files in a storage area used by the Privy Council Office, the department that supports Prime Minister Stephen Harper and the cabinet.
An expensive, painstaking cleanup at the time, however, did not wipe out the creeping menace.
In May this year, employees stumbled across files that had been dried and treated after the flood, yet showed renewed mould growth years later.
The return of the seemingly undead mould not only threatens the paper documents through staining and deterioration, but also the health of anyone who comes in contact with them or the storage environment.
People with respiratory illnesses, such as asthma, are particularly vulnerable to airborne moulds.
"Mould-affected documents are more susceptible to develop mould because they have a higher concentration of mould spores – visible or invisible – that may be dormant, but still viable," says a government notice outlining the problem.
"Considerable effort has been afforded to try and prevent mould growth, yet mould has been recently discovered in some records previously damaged by the flood."
The Privy Council Office is now looking for outside experts to help identify all the fouled folios and kill the contagion, and is expecting to pay up to $100,000 for the work.
And because the documents contain highly sensitive government information, the technicians must have security clearances and surrender their cellphones, laptops and other mobile devices before entering the storage areas.
They're also required to wear protection against hazardous materials, such as latex gloves, mask respirators, lab coats and goggles.
They will vacuum shelves, carpets and concrete floors using dense, high-quality filters to catch the spores. All work must be completed by next September.
"The records are operational and administrative in nature," spokesman Raymond Rivet said in an e-mail.
"They date from 1968-98, with most of the affected records dating to 1988-94. No documents have been destroyed as a result of being affected by mould."
The documents are currently held in a Gatineau, Que., storage warehouse operated by Library and Archives Canada, though under the control of Privy Council Office.
The federal government's biggest repository of historical documents is at Library and Archives, where mould occasionally creeps onto the pages of books, photographs, old newspapers and paper documents, despite strict controls to hold down humidity and temperature levels.
The institution freezes any contaminated documents for at least 48 hours to kill live mould, then treats the damaged material inside a biological containment hood.
Tiny spores are particularly tough to eliminate. Their tough outer shells can protect and keep them dormant for years.
Library and Archives Canada warns members of the public who discover mould in documents to immediately stop handling the material and report it to staff.