Dr Claire Horwell

Coordinator of IVHHN
RCUK Fellow

Institute of Hazard & Risk Research
Department of Earth Sciences
Durham University
Science Labs., South Road
Durham
DH1 3LE, UK

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Research Expertise

Claire Horwell is currently involved in several areas of volcanic health hazard research:
 

1. As a NERC/RCUK Fellow, her research concentrates on addressing a fundamental problem in the field of natural dust hazards: identifying what causes variations in natural dust toxicity. This includes investigation of the mechanism of formation of crystalline silica polymorphs in volcanic settings; assessment of surface occlusion of particles by more-inert minerals, and adaptation of analytical techniques for high-resolution micro-analysis of respirable crystalline silica in natural dusts (coal dust, volcanic ash and desert dusts).
2. Iron-induced reactivity of particle surfaces in different volcanic ash types. This is a hitherto unreported mechanism of toxicity for volcanic particles. Claire’s research, using EPR spectrometry, has shown that all volcanic ash generates hydroxyl radicals, but particularly basaltic ash, which was not previously thought of as a health hazard due to its lack of crystalline silica (Horwell et al., EPSL, 2007; Horwell et al. Env. Res. 2003).
3. Grain-size analysis of volcanic ash for the rapid assessment of volcanic health hazard. Claire has built a database of volcanic ash grain-size analyses, focusing on health-pertinent fractions, to allow rapid assessment of health hazard at the onset of new eruptions. She also has developed a methodology for predicting quantities of respirable material in an ash sample where state-of-the-art analytical techniques are unavailable (Horwell, JEM, 2007).
4. Cristobalite formation in volcanic domes - this work aims to understand the mechanisms by which cristobalite grows in pore-networks within volcanic domes such as the Soufriere Hills, Montserrat. Her PhD student is currently investigating whether all dome-forming volcanoes are capable of generating cristobalite.
5. Development and quantification of a passive sampling device for detection of volcanogenic H₂S (Horwell et al. JEM, 2004; Horwell et al. JVGR, 2005).

Relevant Publications

Martin, R.S., Mather, T.A., Pyle, D.M., Power, M., Tsanev, V.I., Oppenheimer, C., Allen, A.G., Horwell, C.J. and 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.

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., Allen, A.G., Aiuppa, A., Horwell, C.J. and Ward E.P.W. Chemical and morphological characterisation of volcanic aerosols and nanoparticles from Mt Etna. Journal of Geophysical Research – Atmospheres. 113, D17211.

Le Blond, J.S., Williamson, B.J., Horwell, C.J., Monro, A.K., Kirk, C.A. and Oppenheimer, C. 2008. Production of potentially hazardous respirable silica airborne particulate from the burning of sugarcane. Atmospheric Environment. 44, 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. Also see article: “Sizing up the danger of volcanic ash” by E. Morgan, Chemical Technology, RSC Publishing, 10, 2007. http://www.rsc.org/Publishing/ChemTech/Volume/2007/10/volcano.asp

Horwell C.J., Fenoglio, I., Fubini. B. 2007. Iron-induced hydroxyl radical generation from basaltic volcanic ash. Earth and Planetary Science Letters. 261, 662-669.

Stewart, C., Johnston, D.M., Leonard, G., Horwell, C.J., Thordarsson, T. and 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.

Horwell, C.J. and Baxter, P.J. 2006. The respiratory health hazards of volcanic ash: a review for volcanic risk mitigation. Bulletin of Volcanology. 69, 1-24.

Hansell, A. Horwell, C.J. and Oppenheimer, C. 2006. The health hazards of volcanoes and geothermal areas. Commissioned by Occupational and Environmental Medicine Journal's Continuing Professional Development Series. 63, 149-156.

Witham, C.S., Oppenheimer, C. and Horwell, C.J, 2005. Volcanic ash leachates: a review and recommendations for analysis methods. Journal of Volcanology and Geothermal Research, 141, 299– 326.

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. and Patterson, J.E., 2004. Evaluation of a simple passive sampling technique for monitoring volcanogenic hydrogen sulphide. J. Environ. Monitor., 6, 630 - 635.

Horwell, C.J., Fenoglio, I., Ragnarsdottir, K.V., Sparks, R.S.J., and Fubini, B. 2003. Surface reactivity of volcanic ash from the eruption of Soufrière Hills volcano, Montserrat, with implications for health hazards. Environ. Res., 93, 202-215.

Horwell, C.J.,Sparks, R.S.J., Brewer, T.S., Llewellin, E.W., and Williamson, B.J. 2003. The characterisation of respirable volcanic ash from the Soufriere Hills Volcano, Montserrat, with implications for health hazard. Bull. Volcanol., 65, 346-362.

Horwell, C.J., Braña, L.P., Sparks R.S.J., Murphy, M.D., and Hards, V.L. 2001. A geochemical investigation of fragmentation and physical fractionation in pyroclastic flows from the Soufriere Hills volcano, Montserrat. J. Volcanol. Geotherm. Res., 109, 247-262.