John47 At first sight it looks like today, Fri 16, there is no air traffic in Eire, UK, Scandinavia, Finland, Latvia Lithuania, Estonia, Poland, Germany, Benelux, Holland, France, Spain and Portugal.
Clearly all these countries have overreacted and lack the judgement of most posters here.
Don't be fooled. Most of them did it because of "me too" syndrome. Many of those countries do not have qualified practicing specialists in this area. We spoke to 4 different countries MET offices. They admit they have very little clue about real situation. They were just pulling out some volcano-related scientific literature from book shelves yesterday in order to refresh what they last heard in universities 15-40 years ago.
I'm not a specialist too. However I know there are many active volcanos on our planet, but I haven't heard any recently about airspase closures apart from narrow no-fly zones where you can obviously see the dust visually.