Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples

Abstract

BackgroundThe eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland’s volcanoes to Icelandic and Northern European populations.MethodsA physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network.ResultsIcelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m2 g−1, which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO•), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after ‘refreshing’ sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m−2, with mafic samples releasing more iron than silicic samples. All samples were non-reactive in a test of red blood cell-membrane damage.ConclusionsThe primary particle-specific concern is the potential for future eruptions of Iceland’s volcanoes to generate fine, respirable material and, thus, to increase ambient PM concentrations. This particularly applies to highly explosive silicic eruptions, but can also hold true for explosive basaltic eruptions or discrete events associated with basaltic fissure eruptions.

Properties of dust source material and volcanic ash in Iceland

“…Not all volcanic eruptions directly produce this fibrous material, but with time weathering and hydration may alter the morphology forming this fibrous material, typically occurring on the order of thousands of years (Horwell & Baxter, 2006). For most eruptions in Iceland, fibrous material is very rarely created and is dependent on the type of eruption and conditions during the eruption (Dellino et al, 2012;Horwell et al, 2013;Damby et al, 2017). Angular, blocky ash is more common in Iceland, which can be inhaled when the diameter is <10 lm (Horwell et al, 2013).…”

Volcanic air pollution and human health: recent advances and future directions

“…In practice, analyses are rarely completed within the days to weeks over which acute exposures may be occurring, so cannot be relied upon to inform decision-making. Thus, in advance of future eruptions, the hazard could be informed by study of archived ash samples from historic eruptions (Hillman et al 2012;Horwell et al 2010bDamby et al 2017).…”

An Overview of Acute Respiratory Infection Cases Before and After Exposure to Volcanic Ash

“…The main substance in volcanic ash that can cause lung diseases such as fibrosis and cancer is crystalline silica, although not all volcanic eruptions produce volcanic ash containing crystalline silica (Damby et al, 2017). Exposure to volcanic ash containing crystalline silica can worsen a person's condition with opportunistic infections (Damby, Murphy, Horwell, Raftis, & Donaldson, 2016).…”