I'm not able to read the full scientific report, but from the abstract I read it has nothing new in it. We all know that ashes are dangerous to aviation. The question is - from which distance and in what concentration. Articles circling the world now speak of "justified closure of European airspaces", which is complete nonsense. Most of European airspace was nearly particle free and absolutely safe for aviation (let alone for breathing).
More to come...
Dani