The Surveillance of the Air Quality in the Vicinity of an Active Volcano : Case of the Piton de la Fournaise .

Abstract

Atmospheric pollution may be of both anthropogenic and natural origin (Levine, 1996; Finlayson and Pitts, 1999; IPCC, 2000; Delmas et al., 2005). Concerning natural pollution, most active volcanoes emit, among others, gases (eg. sulphur dioxide) and particles into the atmosphere during eruption events (Hobbs et al., 1991; Bhugwant et al., 2009). It is thus important to conduct the monitoring of these pollutants for active volcanoes all over the world, in order to take the adequate measures of air pollution (eg. to establish evacuation plans for the surrounding population) and also to study the long-term trends and effects caused by volcanic activity. In this sense, since a decade the World Health Organization (WHO), the European Community and the French Ministry of Environment (MEDDTL: Ministere de l’Ecologie, du Developpement Durable, du Transport et du Logement) have established SO2 guideline levels, following the severity of the impact of this pollutant on human health and on the environment (WHO, 2005). Previous experimental (ground-based and air-borne) studies indicate that major volcanic eruptions such as Mount St Helens (May 1980), El Chicon (March-April 1982) and Pinatubo (June 1991) injected large amounts of solid particles and volatile gases in the troposphere and the stratosphere, up to an altitude of 25 km high (Turco et al., 1993; Trepte et al., 1993; Krueger et al., 1995; Schneider et al., 1999). Another study showed, in a statistical approach, the global distribution of volcanic SO2 degassing during the last century (1900-2000) and further indicated that each eruption (even for non monitored ones) could affect the stratosphere, based on empirical observations (Hamler et al., 2002). More recently, the eruption of the Eyjafjallajokull volcano in Iceland, which began on April 14th 2010 and ended in October 2010, caused enormous disruption to air travel across western and northern Europe, due to huge amounts of ash and particles emitted in the atmosphere. Volcanic eruptions may cause irreversible environmental and ecological impacts (burial by ash, mud, etc.), via lava or pyroclastic flows, dusts and ash falls and/or gaseous emissions, while they may also increase the economic burden in socio-economic sectors, by causing infrastructure and habitation damages (e.g. houses, buildings, roads, fields and forests covered with ash and/or lava) (Munich Re, 1998; Brosnan, 2000). It is now clearly