Doug Johnson, MET Office UK, Head of Transport illustrates the challenge of volcanic emissions to the atmosphere. He reports the MET Office UK's activities during the volcanic ash crisis of last April. 1st HEC workshop on regulation. Emergency regulation under the thread of a catastrophe: a hard look at the volcanic ash crisis. A conference organised by Alberto Alemanno, HEC Paris. 10 & 11 november 2010. More info at http://www.albertoalemanno.eu