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.
Clearly there are many questions to be answered - amongst which might be what are the relative values of pollution between air traffic and volcano ash.
hmmm