Australia — The calcine sands are a by-product of past gold mining methods and contain small amounts of arsenic and mercury.
They became airborne after vegetation cover was burnt by the fire.
The authority has been rehabilitating the area for the past nine months.
Parks Victoria’s Chris McCormack says it is also part-way through setting up a long-term solution to permanently contain the sands.
“I don’t think it will happen on that site again because whatever we do, it’s going to be a long-term solution,” he said.
“We’ll protect the sands from that exposure. So on land that we’re responsible for, we’ve certainly examined and investigated whether there’s any of these types of materials and we’re satisfied that this is the major one in our area.”