Re the asthma issue, are we likely to be affected by that here in the UK? We are in the south east, and still getting to grips with managing my 6 yr old dd's asthma. She also has allergies which adds to the importance of managing it properly. Does anyone know what it might mean in terms of day to day management of asthma if so2 levels become high enough here to cause a problem? Many thanks and apologies for going slightly off topic.
Depends on just how big the eruption was. This is the wiki description of effects in the UK and the rest of Europe from the Laki eruption which was the last really big eruption:
An estimated 120,000,000 long tons (120,000,000 t) of sulphur dioxide was emitted, about three times the total annual European industrial output in 2006 (but delivered to higher altitudes, hence more persistent), and equivalent to a 1991 Mount Pinatubo eruption every three days.[9] This outpouring of sulphur dioxide during unusual weather conditions caused a thick haze to spread across western Europe, resulting in many thousands of deaths throughout 1783 and the winter of 1784.
The summer of 1783 was the hottest on record and a rare high pressure zone over Iceland caused the winds to blow to the south-east. The poisonous cloud drifted to Bergen in Denmark–Norway, then spread to Prague in the Kingdom of Bohemia (now the Czech Republic) by 17 June, Berlin by 18 June, Paris by 20 June, Le Havre by 22 June, and Great Britain by 23 June. The fog was so thick that boats stayed in port, unable to navigate, and the sun was described as "blood coloured".
Inhaling sulphur dioxide gas causes victims to choke as their internal soft tissue swells – the gas reacts with the moisture in lungs and produces sulfurous acid. The local death rate in Chartres was up by 5% during August and September, with more than 40 dead. In Great Britain, the records show that the additional deaths were among outdoor workers; the death rate in Bedfordshire, Lincolnshire and the east coast was perhaps two or three times the normal rate. It has been estimated that 23,000 British people died from the poisoning.
The weather became very hot, causing severe thunderstorms with large hailstones that were reported to have killed cattle, until the haze dissipated in the autumn. The winter of 1783/1784 was very severe; The naturalist Gilbert White in Selborne, Hampshire, reported 28 days of continuous frost. The extreme winter is estimated to have caused 8,000 additional deaths in the UK. During the spring thaw, Germany and Central Europe reported severe flood damage.
The meteorological impact of Laki continued, contributing significantly to several years of extreme weather in Europe. In France, the sequence of extreme weather events included a surplus harvest in 1785 that caused poverty for rural workers, as well as droughts, bad winters and summers, and a violent hailstorm in 1788 that destroyed crops. These events contributed significantly to an increase in poverty and famine that may have contributed to the French Revolution in 1789. Laki was only one factor in a decade of climatic disruption, as Grímsvötn was erupting from 1783 to 1785, and a 1998 study of El Niño patterns suggests that there was also an unusually strong El Niño effect from 1789 to 1793.
So in answer to your question, is there is a very real danger to pretty much all of us, not just asthma suffers if its a big one. The key word there being if. That is the worst case scenario though.
At the moment its pure speculation, and the smaller eruptions may have taken a lot of energy out of the system as well as the SO2. Its more of an issue with a big explosive eruption which causes the SO2 to get higher up into the atmosphere and be spread further.