Around 10% of the world’s population lives near a historically active volcano. When a volcano erupts, there may be critical dangers for those caught in the explosive force of the eruption (for example, lateral blasts, ballistic ‘bombs’ and pyroclastic density currents). However, by far the most wide-spread hazard is airborne emissions, carried by winds over hundreds to thousands of kilometers from the volcano. These emissions include volcanic ash (particles of fragmented magma less than 2 mm in diameter), aerosols and gases.
Major explosive eruptions are infrequent, even in countries like Indonesia that are well populated by active volcanoes, yet their ash falls can impact on many thousands of people living in their vicinity and occasionally much further afield. Mount St. Helens, in the US, spurred a revolution in risk reduction measures in volcanic crises when it erupted in 1980, leaving its ash covering central Washington State. From that iconic disaster, we learned that massive clouds of fine ash mobilized from ash deposits by wind and traffic will severely limit visibility and disrupt all forms of transport for days in the absence of rainfall, and expose whole populations to dramatically high concentrations of an inhalable mixture of very fine and coarse ash particles in the air.
To test the effectiveness of different types of respiratory protection at filtering volcanic ash, laboratory tests of filtration efficiency (FE) and ‘total inward leakage’ (TIL) (a measure of mask filtration and fit, on volunteers) were conducted at the Institute of Occupational Medicine, Edinburgh, UK. Seventeen different types of protective materials were sourced from communities living near volcanoes, ranging from industry-certified (N95/N99-equivalent masks – FFP2/3) to hijabs, shawls and bandanas.
Every society and, possibly, community in the world may react differently to the hazard of volcanic ash, dependent on many cultural and demographic conditions, which will influence their perceptions of the health risk, and the need to protect themselves.
The health risks of inhaling volcanic ash are still largely unknown, as is the health benefit of reducing exposure through respiratory protection and other interventions. The lack of evidence is primarily due to the challenges of conducting clinical trials and epidemiological surveys in crisis conditions, as well as the difficulties in following cohorts over decades to determine chronic disease risk. This risk is of particular concern at volcanoes which produce crystalline silica in lava domes [9], where eruptions may continue, in phases, over years or decades.
The HIVE project research found that agencies often distribute masks in eruption crises and that these are usually loose-fitting surgical (or similar material) masks [4]. Yet, the laboratory studies showed that such masks offer a low level of protection due to poor fit [3]. In an affiliated project, led by Dr Fiona McDonald (QUT, Australia), we developed a framework to assist agency decision making on which type of respiratory protection to recommend/distribute based on ethical principles [12].
The aim of the HIVE project was to generate an evidence base from which to develop public information on the effectiveness of respiratory protection for volcanic ash exposures.
In September 2017, Mount Agung, Bali, Indonesia, started to show signs of unrest, with swarms of deep earthquakes recorded on seismographs, and felt by communities, indicating movement of magma beneath the volcano. A large eruption looked imminent and, by early October, up to 146,000 people were evacuated, spread across 427 shelters [15].
The International Volcanic Health Hazard Network and the HIVE Project
Authorship and acknowledgements