If "the Icelandic volcano" had stopped erupting, for ever, and if it was the only one like it in the whole world, or indeed if aeroplanes and human lungs were now immune to volcanic emissions, this would be, on the face of it, not a particularly useful tool. Perhaps it could be adapted to give you the local pollen count.
Since none of the circumstances I just proposed are actually true, watch this space. According to BBC World Service's "Discovery" programme this week (stream and/or podcast till next Wednesday), the dangerous (sharp, meltable, electrically conductive) "ash" is liable to be produced, and exploded high into the atmosphere, when water enters "the plumbing" of a volcano, and this has been happening quite a lot this month because the Icelanders have thoughtlessly constructed glaciers on top of their volcanoes. Glaciers made of ice, which is all riht when it's cold, but the thing is, volcanoes are warm. At last word the volcano actually has gone a bit quiet again as far as steam-powered ash explosions are concerned, presumably because one of the explosions stopped any more water getting in - for a while. But as Doctor Who recently told a Mars exploration mission that had problems of their own, "water always wins".