Dust that fell from the ceiling of the intensive care unit at the Royal Hobart Hospital and settled on a patient recovering from surgery is being tested for harmful substances.

The incident happened early on Wednesday afternoon, after a subcontractor working on the roof of the hospital dropped ducting, which caused a metal ceiling tile in the ICU to move.

It comes almost two weeks after asbestos fell from the ceiling in a different hospital building, forcing the relocation of 40 staff.

The dust is being tested for any potentially harmful substances, and results are expected within 24 hours.

The patient was recovering from surgery at the time, and the Tasmanian Health Service (THS) said it was unlikely they were impacted by the dust as they were being ventilated at the time.

The patient has been moved and the area decontaminated as a precaution.

An infection control unit at the hospital has cleaned the area and assessed the bed space as being safe to use.

A THS spokesman said the incident was regrettable and an immediate review was underway.

Work on the roof of the building has been stopped while the subcontractor’s processes are reviewed.

Earlier this week, the hospital confirmed that material found in wall cladding at the hospital’s redevelopment site contained asbestos.

-ABC