Construction of the new pharmacy at the Verdun Hospital has been suspended after air quality tests detected the presence of mould in the walls.
The pharmacy is being built on the third floor which once housed the rehabilitation facility.
Decontaminaton of the site is underway and officials will be meeting later this week to asses the situation.
The Worker Health and Safety Board (CSST) says the mould is confined to the work site and tests in other areas of the hospital indicate the health of patients and staff is not at risk.
The work began in December and will resume once the area has been cleaned up.