The Canada Science and Technology Museum in Ottawa was evacuated Thursday and the museum closed indefinitely after maintenance workers discovered mould in the south wall this week.

The national museum, which was closed earlier this month for annual maintenance, will now remain closed for an undetermined length of time.

 Canada Science and Technology Museum

The Canada Science and Technology Museum will remain closed for an undetermined length of time due to airborne mould. (Andrew Foote/CBC)

Maintenance workers found a leak in the roof Monday and on Tuesday found damage had spread to the south wall. On Wednesday mould was discovered. After test results Thursday found "unacceptable" amounts of airborne mould, workers were told to leave the building, says spokesman Olivier Bouffard.

Bouffard says he doesn't know of any health issues linked to the discovery.

Some birthday parties, group visits and other previously booked events could be cancelled depending on the length of time the museum remains closed.

Museum's first problem with mould, says spokesman

Bouffard says this is the museum's first problem with mould, though it has had other problems with asbestos in the roof before. But he said there are no plans to move.

The museum opened in a former industrial bakery on St Laurent Boulevard in 1967 in what was supposed to be a temporary location.

John Phillips has a membership and said he goes every few weeks with his kids.

"It's a shame that it's closed temporarily, we'll have to find someplace else that's both educational and fun to be with the kids, where they can run around," said Phillips.