The health hazards and impacts of volcanic ash: an interdisciplinary journey towards effective mitigation, protection and communication

The eruption of Mount St. Helens in 1980 exposed a large population to volcanic ash that was found to contain cristobalite – a crystalline silica polymorph and known carcinogen. This event triggered an array of epidemiological, toxicological and geochemical studies to assess the toxicity of ash, marking the birth of a new field of research. This talk will take you on an interdisciplinary journey through the work conducted since the 1980s, which has discovered both biological mechanisms in favour of volcanic ash toxicity and inherent physicochemical characteristics of ash particles that may render the silica surfaces non-toxic. A sparsity of longitudinal clinical and epidemiological studies following eruptions means that medical evidence for chronic ash pathogenicity is lacking, but other research has shown that acute exposures to volcanic ash can exacerbate existing respiratory conditions. Additionally, a multitude of techniques and protocols have been developed for rapid, eruption-specific health hazard assessment, but conducting these assessments in a crisis is very challenging. In the absence of definitive information about the harmfulness of ash, many exposed people choose to protect themselves as a precaution, or are advised to do so by agencies, so recent research has focussed on providing them with the knowledge to do that effectively. This laboratory and community-based research, involving collaborations among geoscientists, exposure scientists, social scientists, medical ethicists, agency and community representatives, has yielded critical insight into a chain of communication from researcher, through various local ‘authorities’, to the actions taken by communities. The findings have led to changes in humanitarian and individual practice and have opened up new pathways to effective uptake of evidence-based advice through co-designed informational products.