Historic information some of may find of interest.
A little over 200 years ago, the eruption of a volcano in Iceland sent a huge toxic cloud across Western Europe. It was the greatest natural disaster to hit modern Britain, killing many thousands - but it has been almost forgotten by history.
The cloud first reached Britain on the 22 June 1783. In his Naturalist's Journal, Gilbert White reported: "The peculiar haze or smoky fog that prevailed in this island and even beyond its limits was a most extraordinary appearance, unlike anything known within the memory of man."
http://news.bbc.co.uk/1/hi/sci/tech/6276291.stm There are a couple of short video clips too.
The "killer fog" first hit Scandinavia, swirled down across Poland and Germany, crossed Belgium and France and then hit the UK formk the south.