Dr Claire Horwell
2013 – present — Senior Lecturer, Institute of Hazard, Risk & Resilience (IHRR), Dept. of Earth Sciences, Durham University, UK
2012 – 2013 — Lecturer, IHRR, Dept. of Earth Sciences, Durham University, UK
2012 – present — Co-Director of IHRR, Durham University, UK
2011 – present — Fellow of the Wolfson Research Institute, Durham University
2003 – present — Director of the International Volcanic Health Hazard Network (IVHHN)
2007 – 2012 — RCUK Fellow, Dept. of Earth Sciences, Durham University, UK.
2007 – 2011 — NERC Post-doctoral Fellow, Dept. of Earth Sciences, Durham University, UK.
2005 – 2007 — NERC Post-doctoral Fellow, Department of Earth Sciences, University of Cambridge, UK.
2003 – 2005 — Leverhulme Trust Post-doctoral Researcher, Department of Earth Sciences, University of Bristol, UK
1999 – 2002 — PhD – NERC-CASE Studentship, University of Bristol, UK
Career Research Highlights
My expertise is in the health hazards of natural and industrial mineral dusts. I am one of a handful of academics, worldwide, who use mineralogical and geochemical techniques to assess respiratory hazard. My multidisciplinary approach combines my physicochemical analyses with collaborators’ medical data to address the ‘structure-toxicity’ relationship of mineral particles. I am founder/director of the International Volcanic Health Hazard Network, the umbrella organisation for volcanic health research and dissemination. My recent research has addressed a fundamental problem: why is crystalline silica variably toxic? Crystalline silica is the mineral of prime health concern in many environmental and industrial settings because it may cause silicosis (a fatal, fibrotic disease) and lung cancer. My research has focused on volcanic ash, particularly that generated from volcanoes which ‘mass-produce’ crystalline silica within lava domes. Globally, 9% of the population lives near a historically active volcano, so ash exposure is an important health concern. A key achievement, and culmination of my NERC Fellowship, has been the discovery that volcanic silica particles are ‘impure’; their surfaces are coated with more-inert phases (such as aluminium-rich glass), and aluminium also substitutes for silica within the crystalline structure. Aluminium is known to dampen silica toxicity, so these findings may explain the apparent low toxicity of volcanic silica. My PhD students are engaged in toxicological research to confirm this.
My research has expanded to include the respiratory toxicity of other siliceous dusts such as coal, desert, combusted biomass and diatomaceous earth particulate, giving me a broad expertise in mineral dust toxicity.
I have acted as advisor to the World Health Organisation, Public Health England (formerly the Health Protection Agency) and the UK Cabinet Office regarding the respiratory health hazards of volcanic ash.
Committee and Society Service (recent)
2013 – present — Member; Expert Advisory Group for Risk H55, UK Government Cabinet Office
2010 – 2011 — Member; Scientific Advisory Committee for Iceland Eruptions; World Health Organization
2011 – present — Member; Health Protection Agency expert panel for future ashfall affecting the UK.
2011 – present — Chair, Education Committee; International Medical Geology Association
2011 – present — Member of Scientific Steering Committee and Project Partner; Global Volcano Model
2005 – 2007 — Representative for Health for the ICSU 5 GeoUnions Initiative; International Union of Geodesy and Geophysics
Conferences and Workshops (recent)
Conference organizer - Volcanic and Magmatic Studies Group Annual Meeting; 2012
International Program committee member and theme chair - Geochemical Society Goldschmidt Conference; 2014
Scientific organizing committee member - Cities on Volcanoes conference; 2012
Organizing committee member - 5th International Conference on Medical Geology; 2013
Session convener & chair: “Characterization and Health Impact of Natural and Anthropogenic Dust” – MEDGEO conference; 2013
Session convener & chair: “Health aspects of volcanic eruptions: learning from recent experience.” – Cities on Volcanoes conference; 2012
Session convener & chair: " Human health problems caused by volcanic activity" - Cities on Volcanoes conference; 2010
Session convener & chair: "Responding to volcanic health hazards" - International Association of Volcanology and Chemistry of the Earth's Interior General Assembly; 2008
Associate Editor, the Journal of Applied Volcanology
2007 – 2012 — Research Councils UK: Fellow
2005 – 2011 — NERC Postdoctoral Fellow
Keynotes and Plenary Talks
2011 — The respiratory health hazards of volcanic ash: a review of current knowledge from a mineralogical and toxicological perspective. Talk presented at GeoMed 2011 conference, Bari, Italy.
2003 — Volcanic emissions and health hazards: past, present and future research. Talk presented at CoV 3, Hilo, Hawaii
Membership of Organisations and Societies
Member, International Medical Geology Association
Member, International Association of Volcanology and Chemistry of the Earth's Interior
Member, European Geosciences Union
Member, American Geophysical Union
Recent and Current Grants
2013 — VERTIGO – Volcanic ash: field, experimental and numerical investigations of processes during its lifecycle. EU Initial Training Network Co-I
2010 — Rapid assessment of the potential health hazard of ash from Eyjafjallajökull volcano, Iceland. NERC Urgency Grant. P.I.
2010 Fragmentation of volcanic dome rock for the assessment of respiratory health hazard of fresh particulate matter. Part of EVOKES ERC Advanced Investigator grant (Dingwell)
2008 — Moyes Foundation PhD Studentship Bursary. Volcanic cristobalite formation: A global study for the assessment of health hazard. 3 year Studentship from Jan. 2009. P.I.
2008 — NERC Urgency Grant. Rapid assessment of the potential health hazard of ash from Kilauea Volcano, Hawai’i. Extended after award to include Chaitén, Chile eruption. P.I.
Department of Earth Sciences
- The Solid Earth
Department of Geography
- Stewart, C., Johnston, D.M., Leonard, G., Horwell, C.J., Thordarsson, T. & Cronin, S. (2006). Contamination of water supplies by volcanic ashfall: A literature review and simple impact modelling. Journal of Volcanology and Geothermal Research 158: 296-306.
- Hansell, A. Horwell, C.J. & Oppenheimer, C. (2006). The health hazards of volcanoes and geothermal areas. Occupational and Environmental Medicine 63(Continuing Professional Development Series): 149-156.
- Horwell, C.J. & Baxter, P.J. (2006). The respiratory health hazards of volcanic ash: a review for volcanic risk mitigation. Bulletin of Volcanology 69: 1-24.
- Witham, C.S., Oppenheimer, C. & Horwell, C.J. (2005). Volcanic ash leachates: a review and recommendations for analysis methods. Journal of Volcanology and Geothermal Research 141: 299-326.
- Weinstein, P., Horwell, C.J. & Cook, A. (2013). Volcanic emissions and health. In Essentials of Medical Geology. Selinus, O., Alloway, B., Centeno, J.A., Finkelman, R.B., Fuge, R., Lindh, U. & Smedley P. Springer. 805.
- Derbyshire, E., Horwell, C.J., Tetley, T. & Jones, T.P. (2011). Airborne Paricles. In Pollutants, human health and the environment: Introduction for environmental scientists and health professionals. Plant, J.A., Ragnarsdottir, K.V. & Vouvoulis, N. Wiley. 255-286.
Journal papers: academic
- Horwell, C.J., Hillman, S.E., Cole, P.D., Loughlin, S.C., Llewellin, E.W., Damby, D.E. & Christopher, T. (2014). Controls on variations in cristobalite abundance in ash generated by the Soufrière Hills volcano, Montserrat in the period 1997-2010. Memoir of the Geological Society of London 39: 399-406.
- Baxter, P J, Searl, A, Cowie, H A, Jarvis, D & Horwell, C J (2014). Evaluating the respiratory health risks of volcanic ash at the eruption of the Soufrière Hills Volcano, Montserrat, 1995-2010. Memoir of the Geological Society of London 39(22).
- Damby, D.E., Llewellin, E.W., Horwell, C.J., Williamson, B.J., Najorka, J., Cressey, G. & Carpenter, M.A. (2014). The α-β phase transition in volcanic cristobalite. Journal of Applied Crystallography 47(4): 1205-1215.
- Le Blond, J.S., Tomatis, M., Horwell, C.J., Dunster, C., Murphy, F., Corazzari, I., Grendene, F., Turci, F., Gazzano, E., Ghigo, D., Williamson, B.J., Oppenheimer, C. & Fubini, B. (2014). The surface reactivity and implied toxicity of ash produced from sugarcane burning. Environmental Toxicology 29(5): 503-516.
- Horwell, C.J., Williamson, B.J., Llewellin, E.W., Damby, D.E. & Le Blond, J.S. (2013). Nature and formation of cristobalite at the Soufriere Hills Volcano, Monserrat: implications for the petrology and stability of silicic volcanic domes. Bulletin of Volcanology 75: 696.
- Horwell, C J, Baxter, P J, Hillman, S E, Calkins, J A, Damby, D E, Delmelle, P, Donaldson, K, Dunster, C, Fubini, B, Hoskuldsson, A, Kelly, F J, Larsen, G, Le Blond, J S, Livi, K J T, Mendis, B, Murphy, F, Nattrass, C, Sweeney, S, Tetley, T D, Thordarson, T & Tomatis, M (2013). Physicochemical and toxicological profiling of ash from the 2010 and 2011 eruptions of Eyjafjallajökull and Grímsvötn volcanoes, Iceland using a rapid respiratory hazard assessment protocol. Environmental Research 127: 63-73.
- Damby, D.E., Horwell, C.J. , Baxter, P.J., Delmelle, P., Donaldson, K., Dunster, C., Fubini, B., Murphy, F.A., Nattrass, C., Sweeney,S., Tetley, T.D. & Tomatis, M. (2013). The respiratory health hazard of tephra from the 2010 Centennial eruption of Merapi with implications for occupational mining of deposits. Journal of Volcanology and Geothermal Research 261: 376-387.
- Stevenson, J.A., Loughlin, S.C., Font, A., Fuller, G.W., MacLeod, A., Oliver, I.W., Jackson, B., Horwell, C.J., Thordarson, T. & Dawsonvenson, I. (2013). UK monitoring and deposition of tephra from the May 2011 eruption of Grímsvötn, Iceland. Journal of Applied Volcanology 2(1): 3.
- Hillman, S.E., Horwell, C.J., Densmore, A.L., Damby, D.E., Fubini, B., Ishimine, Y. & Tomatis, M. (2012). Sakurajima volcano: a physico-chemical study of the health consequences of long-term exposure to volcanic ash. Bulletin of Volcanology 74(4): 913-930.
- Horwell, CJ, Williamson, BJ, Donaldson, K, Le Blond, JS, Damby, DE & Bowen, L (2012). The structure of volcanic cristobalite in relation to its toxicity; relevance for the variable crystalline silica hazard. Particle and Fibre Toxicology 9(November 2012 ): 44.
- Le Blond, J S, Tomatis, M, Horwell, C J, Dunster, C, Murphy, F, Corazzari, I, Grendene, F, Turci, F, Gazzano, E, Ghigo, D, Williamson, B J, Oppenheimer, C & Fubini, B (2012). The surface reactivity and implied toxicity of ash produced from sugarcane burning. Environmental Toxicology n/a.
- Horwell CJ, Stannett GW, Andronico D, Bertagnini A, Fenoglio I, Fubini B, Le Blond JS & Williamson BJ (2010). A physico-chemical assessment of the health hazard of Mt. Vesuvius volcanic ash. Journal of Volcanology and Geothermal Research 191(3-4): 222-232.
- Durant AJ, Bonadonna C & Horwell CJ (2010). Atmospheric and environmental impacts of volcanic particulates. Elements 6(4): 235-240.
- Horwell CJ, Le Blond JS, Michnowicz SAK & Cressey G (2010). Cristobalite in a rhyolitic lava dome: Evolution of ash hazard. Bulletin of Volcanology 72(2): 249-253.
- Le Blond JS, Horwell CJ, Williamson BJ & Oppenheimer C (2010). Generation of crystalline silica from sugarcane burning. Journal of Environmental Monitoring 12(7): 1459-1470.
- Williamson BJ, Di Muro A, Horwell CJ, Spieler O & Llewellin EW (2010). Injection of vesicular magma into an andesitic dome at the effusive–explosive transition. Earth and Planetary Science Letters 295(1-2): 83-90.
- Le Blond JS, Horwell CJ, Baxter PJ, Michnowicz SAK, Tomatis M, Fubini B, Delmelle P, Dunster C & Patia H (2010). Mineralogical analyses and in vitro screening tests for the rapid evaluation of the health hazard of volcanic ash at Rabaul volcano, Papua New Guinea. Bulletin of Volcanology 72(9): 1077-1092.
- Le Blond, J.S., Cressey, G, Horwell, C.J. & Williamson, B.W. (2009). A rapid method for quantifying single mineral phases in heterogeneous natural dusts using X-ray diffraction. Powder Diffraction 24: 17-23.
- Martin, R.S., Mather, T.A., Pyle, D.M., Power, M., Tsanev, V.I., Oppenheimer, C., Allen, A.G., Horwell, C.J. & Ward E.P.W. (2009). Size distributions of fine silicate and other particles in Masaya's volcanic plume. Journal of Geophysical Research – Atmospheres 114: D09217.
- Martin, R S. Mather, T A., Pyle, D M., Power, M., Allen, A G., Aiuppa, A., Horwell, C J. & Ward, E P W. (2008). Composition-resolved size distributions of volcanic aerosols in the Mt. Etna plumes. Journal of Geophysical Research - Atmospheres 113: D17211.
- Le Blond, J S., Williamson, B J., Horwell, C J., Monro, A K., Kirk, C A. & Oppenheimer, C. (2008). Production of potentially hazardous respirable silica airborne particulate from the burning of sugarcane. Atmospheric Environment 42(22): 5558-5568.
- Horwell, C.J. (2007). Grain-size analysis of volcanic ash for the rapid assessment of respiratory health hazard. Journal of Environmental Monitoring 9: 1107-1115.
- Horwell, C.J., Fenoglio, I. & Fubini, B. (2007). Iron-induced hydroxyl radical generation from basaltic volcanic ash. Earth and Planetary Science Letters 261(3-4): 662-669.
- Horwell, C.J., Patterson, J.E., Gamble, J.A. & Allen, A.G. (2005). Monitoring and mapping of hydrogen sulphide emissions across an active geothermal field: Rotorua, New Zealand. Journal of Volcanology and Geothermal Research 139: 259-269.
- Horwell, C.J., Allen, A.G., Mather, T.A. & Patterson, J.E. (2004). Evaluation of a novel passive sampling technique for monitoring volcanogenic hydrogen sulphide. Journal of Environmental Monitoring 6(7): 630-635.
- Horwell, C.J., Sparks, R.S.J., Brewer, T.S., Llewellin, E.W. & Williamson, B.J. (2003). Characterization of respirable volcanic ash from the Soufrière Hills volcano, Montserrat, with implications for human health hazards. Bulletin of Volcanology 65(5): 346-362.
- Horwell, C.J., Fenoglio, I., Ragnarsdottir, K.V., Sparks, R.S.J. & Fubini, B. (2003). Surface reactivity of volcanic ash from the eruption of Soufrière Hills volcano, Monserrat, West Indies with implications for health hazards. Environmental Research 93(2): 202-215.
- Horwell, C.J., Braña, L.P., Sparks, R.S.J., Murphy, M.D. & Hards, V.L. (2001). A geochemical investigation of fragmentation and physical fractionation in pyroclastic flows from from the Soufriere Hills volcano, Montserrat. Journal of Volcanology and Geothermal Research 109(4): 247-262.
- Jones, A.P. Bentham, G. & Horwell, C. (1999). Health service accessibility and deaths from asthma. International Journal of Epidemiology 28: 101-105.