We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Durham University

Department of Earth Sciences

Staff Profile

Prof. Claire Horwell, PhD

Professor of Geohealth in the Department of Earth Sciences
Telephone: +44 (0) 191 33 42253
Room number: Rm 248
Member of the Durham X-ray Centre
Management Board Member in Institute of Hazard, Risk and Resilience
Telephone: +44 (0) 191 33 42253

Contact Prof. Claire Horwell (email at


2016 - present - Associate Professor (Reader), Institute of Hazard, Risk & Resilience (IHRR), Dept. of Earth Sciences, Durham University, UK

2013 – 2016 — Senior Lecturer, Durham University, UK

2012 – 2013 — Lecturer, 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

I am founder/director of the International Volcanic Health Hazard Network, the umbrella organisation for volcanic health research and dissemination. I have acted as advisor to the World Health Organization, Public Health England (formerly the Health Protection Agency) and the UK Cabinet Office regarding the respiratory health hazards of volcanic ash. I also work with the New Zealand government and agencies, helping them to prepare for future volcanic eruptions.

My research interest is in understanding the health hazards of natural and industrial mineral dusts and in helping communities to prepare for, and protect themselves from volcanic emissions. My research is split into several, interdisciplinary strands:

Are mineral particles harmful when inhaled?

i) Physicochemical analysis of particles: use of mineralogical and geochemical techniques to assess respiratory hazard. These are combined with my students' and collaborators’ toxicological assessements to determine potential respiratory hazard of volcanic ash, combusted biomass, diatomaceous earth, desert dust and coal dust.

ii) Fundamental questions surrounding the ‘structure-toxicity’ relationship of mineral particles and interacting elements (e.g. anthropogenic pollution), and the variable toxicity of crystalline silica are also addressed through mineralogical, geochemical and toxicological analyses. Petrological techniques are also employed to understand how crystalline silica forms in volcanic systems (paricularly lava domes).

iii) Exposure assessments to airborne particles is a key part of determining potential hazard. My group regularly conducts air quality assessments using state-of-the-art portable aerosol monitors, in environmental and industrial settings.

How can communities prepare for, and protect themselves from, airborne volcanic emissions? 

iv) Public health guidelines on community protection are often generic. Working with Hawaii state and federal agencies, we worked with local communities to understand their lifestyles, and how their current protective strategies, in relation to the 'vog' emissions from Kilauea Volcano, relate to official advice. The findings of focus groups and social surveys enabled a new interagency partnership to revise official advice, which is now available through a dedicated online 'vog' portal ( and as a booklet, rack brochure and poster.

v) Working with the World Health Organization (PAHO) and governmental and non-governmental agencies in Indonesia, Mexico and Japan, the Health Interventions in Volcanic Eruptions (HIVE) project ( is building the first evidence base on effective respiratory protection for communities during volcanic eruptions. We are conducting laboratory experiments, social surveys (both anthropological and psychology-based) and a clinical trial.

Committee and Society Service (recent)

2017- present - President-elect and Founding Leader; GeoHealth Section, American Geophysical Union

2015- present - Member; Scientific Advisory Group for Emergencies (SAGE) for volcanic eruptions, UK Government

2014 – 2017— Chair, Nominations & Awards Committee; International Medical Geology Association

2013 – 2015— Member; Expert Advisory Group for Risk H55, UK Government Cabinet Office

2011 – present — Member; Health Protection Agency expert panel for future ashfall affecting the UK

2011 – present — Member of Scientific Steering Committee and Project Partner; Global Volcano Model

2011 – 2014 — Chair, Education Committee; International Medical Geology Association

2010 – 2011 — Member; Scientific Advisory Committee for Iceland Eruptions; World Health Organization

2005 – 2007 — Representative for Health for the ICSU 5 GeoUnions Initiative; International Union of Geodesy and Geophysics

Editorial Roles

Associate Editor, Journal of Applied Volcanology


2007 – 2012 — Research Councils UK: Fellow

2005 – 2011 — NERC Postdoctoral Fellow

Recent and Current Grants

2015 - HIVE - Health Interventions in Volcanic Eruptions. Research Into Health in Humanitarian Crises Programme; Wellcome Trust & DfID.

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.

Research Groups

Department of Earth Sciences

Department of Geography

Selected Publications

Chapter in book

  • Horwell, C.J., Baxter, P.J. & Kamanyire, R. (2015). Health Impacts of Volcanic Eruptions. In Global Volcanic Hazards and Risk. Loughlin, S.C., Vye-Brown, C., Sparks, R.S.J., Brown S.K. & Jenkins, S.F. Cambridge University Press.
  • Baxter, P.J. & Horwell, C.J. (2015). Impacts of eruptions on human health. In The Encyclopedia of Volcanoes. Sigurdsson, H., Houghton, B., McNutt, S., Rymer, H. & Stix, J. Elsevier.
  • 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 Article

  • Covey, Judith, Horwell, Claire J., Rachmawati, Laksmi, Ogawa, Ryoichi, Martin-del Pozzo, Ana Lillian, Armienta, Maria Aurora, Nugroho, Fentiny & Dominelli, Lena (2019). Factors motivating the use of respiratory protection against volcanic ashfall a comparative analysis of communities in Japan, Indonesia and Mexico. International Journal of Disaster Risk Reduction 35: 101066.
  • Cherrie, J.W., Apsley, A., Cowie, H., Steinle, S., Mueller, W., Lin, C., Horwell, C.J., Sleeuwenhoek, A. & Loh, M. (2018). Effectiveness of face masks used to protect Beijing residents against particulate air pollution. Occupational and Environmental Medicine 75(6): 446-452.
  • Galea, K.S., Covey, J., Mutia Timur, S., Horwell, C.J., Nugroho, F. & Mueller, W. (2018). Health Interventions in Volcanic Eruptions—Community Wearability Assessment of Respiratory Protection against Volcanic Ash from Mt Sinabung, Indonesia. International Journal of Environmental Research and Public Health 15(11): 2359.
  • Tomašek, I., Horwell, C.J., Bisig, C., Damby, D.E., Comte, P., Czerwinskid, J., Petri-Fink, A., Clift, M.J.D., Drasler, B. & Rothen-Rutishauser, B. (2018). Respiratory hazard assessment of combined exposure to complete gasoline exhaust and respirable volcanic ash in a multicellular human lung model at the air-liquid interface. Environmental Pollution 238: 977-987.
  • Steinle, S, Sleeuwenhoek, A, Mueller, W, Horwell, CJ, Apsley, A, Davis, A, Cherrie, JW & Galea, KS (2018). The effectiveness of respiratory protection worn by communities to protect from volcanic ash inhalation; Part II: Total inward leakage tests. International Journal of Hygiene and Environmental Health 221(6): 977-984.
  • Mueller, W., Horwell, C.J., Apsley, A., Steinle, S., McPherson, S., Cherrie, J.W. & Galea, K.S. (2018). The effectiveness of respiratory protection worn by communities to protect from volcanic ash inhalation. Part I: Filtration efficiency tests. International Journal of Hygiene and Environmental Health 221(6): 967-976.
  • Damby, D.E., Horwell, C.J., Baxter, P.J., Kueppers, U., Schnurr, M., Dingwell, D.B. & Duewell, P. (2018). Volcanic Ash Activates the NLRP3 Inflammasome in Murine and Human Macrophages. Frontiers in Immunology 8: 2000.
  • Damby, D.E., Horwell, C.J., Larsen, G., Thordarson, T., Tomatis, M., Fubini, B. & Donaldson, K. (2017). Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples. Environmental Health 16: 98.
  • Le Blond, J.S., Woskie, S., Horwell, C.J. & Williamson, B.J. (2017). Particulate matter produced during commercial sugarcane harvesting and processing: a respiratory health hazard? Atmospheric Environment 149: 34-46.
  • Nattrass, C., Horwell, C.J., Damby, D.E., Brown, D. & Stone, V. (2017). The effect of aluminium and sodium impurities on the cytotoxicity and pro-inflammatory potential of cristobalite. Environmental Research 159: 164-175.
  • Horwell, C. J., Sargent, P., Andronico, D., Lo Castro, M. D., Tomatis, M., Hillman, S. E., Michnowicz, S. A. K. & Fubini, B. (2017). The iron-catalysed surface reactivity and health-pertinent physical characteristics of explosive volcanic ash from Mt. Etna, Italy. Journal of Applied Volcanology 6(1): 12.
  • Horwell, C.J., Ferdiwijaya, D., Wahyudi, T. & Dominelli, L. (2017). Use of respiratory protection in Yogyakarta during the 2014 eruption of Kelud, Indonesia: Community and agency perspectives. Journal of Volcanology and Geothermal Research
  • Tomašek, I., Horwell, C.J., Damby, D.E., Barošová, H., Geers, C., Petri-Fink, A., Rothen-Rutishauser, B. & Clift, M.J.D. (2016). Combined exposure of diesel exhaust particles and respirable Soufrière Hills volcanic ash causes a (pro-)inflammatory response in an in vitro multicellular epithelial tissue barrier model. Particle and Fibre Toxicology 13(1): 67.
  • Damby, D.E., Murphy, F.A., Horwell, C.J., Raftis, J. & Donaldson, K. (2016). The in vitro respiratory toxicity of cristobalite-bearing volcanic ash. Environmental Research 145: 74-84.
  • Horwell, C.J., Damby, D.E. & Hillier, S. (2015). Respirable volcanic ash is distinct mineralogically, physicochemically and toxicologically from soils originating from weathered volcanic products. A comment on Cervini-Silva et al. (2014) “Lipid peroxidation and cytotoxicity induced by respirable volcanic ash”. Journal of Hazardous Materials 285: 366-367.
  • Nattrass, C., Horwell, C.J., Damby, D.E., Kermanizadeh, A. Brown, D.M. & Stone, V. (2015). The global variability of diatomaceous earth toxicity: a physicochemical and in vitro investigation. Journal of Occupational Medicine and Toxicology 10: 23.
  • 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).
  • Samarasundera, E, Hansell, A, Leibovici, D, Horwell, C.J., Anand, S & Oppenheimer, C (2014). Geological hazards: from early warning systems to public health toolkits. Health & Place 30: 116-119.
  • 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.
  • 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. & Dawson, I. (2013). UK monitoring and deposition of tephra from the May 2011 eruption of Grímsvötn, Iceland. Journal of Applied Volcanology 2: 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, C.J., Williamson, B.J., Donaldson, K., Le Blond, J.S., Damby, D.E. & 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 29(5): 503-516.
  • 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 J.S., Horwell C.J., Williamson B.J. & Oppenheimer C. (2010). Generation of crystalline silica from sugarcane burning. Journal of Environmental Monitoring 12(7): 1459-1470.
  • Williamson, B.J., Di Muro A., Horwell C.J., Spieler O. & Llewellin E.W. (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, J.S., Horwell, C.J., Baxter, P.J., Michnowicz, S.A.K., 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.
  • 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(3-4): 296-306.
  • Hansell, A., Horwell, C.J. & Oppenheimer, C. (2006). The health hazards of volcanoes and geothermal areas. Occupational and Environmental Medicine 63(2): 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): 1-24.
  • 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.
  • Witham, C.S., Oppenheimer, C. & Horwell, C.J. (2005). Volcanic ash-leachates: a review and recommendations for sampling methods. Journal of Volcanology and Geothermal Research 141(3-4): 299-326.
  • 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.

Show all publications