Evaluating the respiratory health risks of volcanic ash at the eruption of the Soufrière Hills Volcano, Montserrat, 1995 to 2010

The management and outcomes of the volcanic crisis on Montserrat, which began with the onset of activity at the Soufrière Hills Volcano (SHV) on 18 July 1995, might have been very different without the scientific precedents set by the Mount St Helens eruption, USA, on 18 May 1980, and the research advances that followed. This narrative is intended to show the steps taken by health scientists in response to the unfolding developments at the volcano to characterize the hazard presented by the volcanic ash and to devise mitigation measures to prevent the development of irreversible lung disease in the island population. Initial assessments of the health risk for silicosis were deterministic and based on industry exposure limits derived from published epidemiological and clinical studies of workers exposed to dusts containing free crystalline silica. However, by 2003, new research findings on the ash enabled the risk to be updated with a probabilistic approach incorporating the expertise of scientists from a wide range of disciplines including toxicology, volcanology and statistical modelling. The main outcome has been to provide reassurance to the islanders and policy makers that the chances of developing silicosis on Montserrat are very small given the preventive measures that were adopted during 1995–2010 and the change in style of the eruption