The health clinic in Norman Wells, N.W.T., reopened Monday morning, after a mercury spill forced it to close for about a week.

The spill came from a blood pressure instrument that broke Feb. 8, leaking mercury at the top of the health centre's stairs and in the entryway.

Colin Eddie, director of health and social programs for the Sahtu Health and Social Services Authority, told CBC News the instrument was being transported from a vehicle into the clinic when the leak was spotted.

"It wasn't dropped. It was really well packed," Eddie said Monday.

"We think that what happened was … the temperature differential, going from the hot vehicle into -50 C, which was what it was outdoors at that time, caused the glass to crack."

Some volunteers in the community, who are trained to deal with mercury spills, got the initial clean-up work done, the director said.

However, the centre was ordered by the Workers' Compensation Board of the Northwest Territories to keep the clinic closed until the level of mercury in the air was well below national standards.

Part of the clinic was open for emergencies throughout last week. Eddie said the clean-up has now been completed and the centre was back to normal as of Monday.

He said the health authority is working to get thermometers and other medical instruments containing mercury out of the region.