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The dust was found last week on the seventh floor of the Dunedin Civic Centre, where roof repairs and refurbishment are being carried out.
Dunedin City Council chief executive Sandy Graham said it was a small amount of asbestos dust and the council had taken a precautionary approach.
Staff who normally worked on that floor were asked to work from home while the discovery was investigated by specialist asbestos consultants, Ms Graham said.
WorkSafe was also notified, she said.
Asbestos is a human carcinogen.
Ms Graham said asbestos specialists cleaned the area, checked ceiling spaces and conducted air quality testing throughout the building.
No further signs of asbestos had been found and test results came back clear.
Most staff had returned to the office.
"A small number are still working from home and we are working with them to ensure they feel comfortable returning to the civic centre," Ms Graham said.
The roof repairs programme remained on track and on budget and it was expected the work would be completed by June next year.