Potentially dangerous silica nanofibres have been identified in airbourne ash spewed across southern South America by a Chilean volcano. Martin Reich and his colleagues at the University of Chile in Santiago used high-resolution transmission electron microscopy to image the one-dimensional crystalline silica nanostructures, called cristobalites. They were formed during the eruption of Patagonia's Chaitén Volcano, which began on 2 May 2008 and is ongoing.
The researchers propose that amorphous silica was reduced by carbon monoxide and then oxidized to become breathable crystalline nanostructures. The formation of these structures was enhanced by micrometre- to nanometre-sized silica glass fragments in the volcanic column.