SDHB health and safety manager Rangi Solomon said staff were relocated from the Fraser Building as a precaution after what was though to be non-toxic mould was found.
Staff would not return until the results of airborne testing were known but initial results indicated the mould was non-toxic, Mr Solomon said.
Testing was expected to take about a three weeks.
As the area was non-clinical there was no effect on patients, Mr Solomon said.
Occupational health and safety nurses were made available to staff, he said.