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|Refer also to 'Health Hazards of Volcanic Ash - A Guide for the Public' on the International Volcanic Health Hazard Network (IVHHN) website. IVHHN was created in February 2003 with the goal to determine the health effects of volcanic emissions, including ash. IVHHN consists of experts and correspondents working in diverse scientific disciplines, such as volcanology, epideminology, toxicology, public health and physical chemistry. A major goal of IVHHN is to produce guidelines and protocols on volcanic health hazard management, which will be ratified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) and disseminated through volcano observatories to the public, scientists, local health practitioners and emergency managers. According to the IVHHN Web site, recommended safety guidelines for dealing with volcanic ash are being written.|
Common respiratory symptoms
Potential respiratory symptoms from the inhalation of volcanic ash depend on a number of factors, including airborne concentration of total suspended particles, proportion of respirable particles in the ash (less than 10 microns in diameter), frequency and duration of exposure, presence of free crystalline silica and volcanic gases or aerosols mixed with the ash, meteorological conditions, and host factors (existing health conditions and the propensity of those exposed to incur respiratory problems), and the use of respiratory protective equipment.
Acute respiratory symptoms commonly reported by people during and after ash falls (Blong, 1984, p. 83-91):
These short-term effects are not considered harmful for people without existing respiratory conditions. People should take steps to minimize their exposure to breathing ash (see mitigation measures).
Because volcanic ash is abrasive, people typically experience eye discomfort or irritation during and after ash fall, especially among those that use contact lenses. Commonly reported symptoms of ash include:
Individuals with Dry Eye Syndrome may also experience ailments due to the presence of ash. No chronic effects of ash on eyes have been noted. Following the 18 May 1980 eruption of Mount St. Helens, a "telephone survey conducted in several ash-affected communities suggested that 4-8 percent of the population experienced eye irritation but that only one in ten of these sought medical advice" (Blong, 1984, p. 90).
Minor skin irritations are sometimes reported following ashfall. Following the 18 May 1980 eruption of Mount St. Helens, however, physicians interviewed in Yakima, Washington, located 120 km east of the volcano, reported no increase in chronic skin irritations.
Mechanical effects || Roof collapse || Automobile accidents ||
The weight of volcanic ash on roofs can lead to their collapse, especially if the ash is wet and the building is not designed to support a heavy load. When a roof collapses under the strain of ash, people suffer direct injury or be killed. See effects of ash on roofs.
Driving in ashy conditions may be difficult or impossible due to slippery road conditions or poor visibility, resulting in automobile accidents that cause injuries. See Roads and Highways for driving conditions and safety strategies during and after an ashfall.
Chronic medical aspects || Crystalline silica || Free silica in ash || More information ||
Free crystalline silica in volcanic ash
Volcanic ash may contain varying proportions of free crystalline silica (silicon dioxide, SiO2) in the form of quartz, cristobalite, or tridymite minerals. The minerals are described as "free" silica because the silicon dioxide compound is not attached to another element to create a new mineral; for example, magnesium to form the mineral olivine. Exposure to respirable particles of free crystalline silica can lead to silicosis, a disease resulting in scarring of the lungs and impairment of their function.
Although there have been no documented cases of silicosis attributed to free crystalline silica in volcanic ash from eruptions in the past few decades, detailed studies for lengthy periods of time necessary to determine the potential long-term effects of ash are notably lacking.
The U.S. National Institute for Occupational Safety and Health (NIOSH) recommended in 1974 the exposure to respirable free silica be limited to 50 micrograms/m3 of air for workers up to a 10-hour work day, 40-hour work week over a lifetime. Historical data suggests that this exposure has been exceeded for brief periods of time (hours to days) in certain locations, but not over the working lifetime of people (2-3 decades).
Proportion of free crystalline silica in volcanic ash
Mount St. Helens, USA
Volcanic ash from the 9-hour explosive eruption on 18 May 1980 that fell across eastern Washington consisted of 3 to 7 percent free silica (cristobalite and quartz) in the sub-10 micron size fraction.
At this proportion of free silica, the NIOSH-recommended standard would be exceeded if exposure to respirable ash was regularly greater than 0.8 to 1.0 milligram/m3 of air (Baxter and others., 1981).
Exposures to the ash and free silica by the general population in the affected communities of eastern Washington were of limited duration, and silicosis was not considered a potential threat to the general population. People who worked in areas of high concentrations of respirable ash, for example loggers removing timber near the volcano or agricultural workers in central Washington, were advised to take protective action. (See Bulletin #13, Research into the free crystalline silica content of Mount St. Helens ash, issued by the Mount St. Helens Technical Information Network.)
Media caution: Within days of the 1980 eruption, there were reports in the media that the volcanic ash from Mount St. Helens contained 60 percent or more free crystalline silica—far greater than the actual 3 to 7 percent of the respirable size fraction. This misinformation may have occurred because chemical analysis of ash and lava is commonly reported in terms of the percentage of total silica content, ranging from about 45 to 77 percent; the analysis includes that which is chemically combined with other elements, not free silica.
Soufriere Hills Volcano, Montserrat
The extended eruption of a lava dome at Soufriere Hills Volcano that began in 1995 generated large amounts of fine ash by (1) explosive events from the dome; and (2) frequent collapse of unstable parts of the growing dome that generated pyroclastic flows and associated plumes of ash. A detailed study of ash from both types of events determined that the sub-10 micron fraction of ash from the pyroclastic flows consisted of 10-24 percent crystalline silica, the highest yet documented for a historical eruption (Baxter and others, 1999). In contrast, the sub-10 micron fraction of ash from the explosive events consisted of 3-6 percent crystalline silica. The free silica minerals are produced within the lava dome over a period of many days or weeks.
Monitoring of the concentration of airborne respirable dust and ash around the volcano beginning in August 1997 showed that concentrations of ash have regularly exceeded 50 micrograms/m3 per 24-hour rolling average in areas subject to frequent ash fall. The exposures to cristobalite sometimes reached the 0.05 mg/m3 averaged over an 8-hour workday. Also, the monitoring consistently showed increased concentrations of airborne dust whenever there was human activity.
This study raises concern that exposure to long-lived eruptions of lava domes that produce persistent ash fall over many years may result in adverse health effects in affected communities.
Crystalline silica health and safety topic, U.S. Department of Labor, Occupational Safety & Health Administration.
A Guide to working safely with silica, U.S. Department of Labor, Occupational Safety & Health Administration.
Historical eruptions: examples of effects of ash on human health
|Volcano; Nation; eruption year||Deaths||Injury||Eyes||Respiratory||Nasal|
|Mount St. Helens; 1980||yes||yes||yes|
|El Chichon; Mexico; 1982||yes, by roof collapse||yes||yes|
|Mount Pinatubo; Philippines 1991||yes, by roof collapse|
|Rabaul; Papua New Guinea; 1994||yes, by asphyxiation|
|Usu Volcano; Japan; 1994||yes, by asphyxiation|
|Fogo; Cape Verde Islands; 1995||yes|
|Cerro Negro; Nicaragua; 199?||yes|
|Etna; Italy; 1999||yes|
|Mt. Cameroon; Cameroon; 1999||yes||yes|
|Pacaya; Guatemala; 1998||yes||yes|
|Telica; Nicaragua; 1999||yes||yes||yes|
Ruapehu, New Zealand—Respiratory effects
The 1995-96 eruption of Mount Ruapehu in New Zealand resulted in several ash falls on many communities, but none received more than a few millimeters of ash. It was estimated that 20 percent by weight was less than 30 microns in diameter. An increase of bronchitis was detected even with such a small amount of ash and the relatively low respirable portion. No other respiratory diseases were detected in the affected areas, and researchers found no evidence for exacerbation of asthma in children living in the ash fall areas (Johnston and Becker, 2001).
Mitigation measures || General public || Children || Overview table ||
People everywhere quickly develop simple methods for protecting themselves from ash fall and the billowing ash stirred up by wind and human activities. The basic strategy is to avoid unnecessary exposure to airborne ash and wear an appropriate and safe facemask when exposed to ash, especially during clean-up operations.
People are rarely evacuated from an area because ash is endangering human health. People with respiratory disease or symptoms, however, may elect on their own to leave an area of high exposure or heavy ash fall. If concentrations of respirable free crystalline silica in the ash exceed the NIOSH-recommended limit of 50 micrograms/m3 for an extended period of time (for example, months to years), the risk of silicosis should not be ignored.
Modified from, FEMA, 1984
Children face the same hazards from the suspension of ash as other age groups, but their exposure may be increased because they are physically smaller and are less likely to adopt reasonable, prudent, preventive measures to avoid unnecessary exposure to ash. After the ash fall from the 1980 eruption of Mount St. Helens, the following recommendations were offered to the public by the Mount St. Helens Technical Information Network:
Modified from, Mount St. Helens Technical Information Network (Bulletin 14), 1980
|Consequence||Health effect||Monitoring||Preventive measure|
|Inhalation of ash less than 10 microns in diameter||Exacerbation of pre-existing lung disease||Monitor
total suspended particulate (TSP)
Monitor ash particles <10 micron in diameter
Protect home and offices from ash infiltration
|Inhalation of free silica in volcanic ash||Silicosis—chronic silicosis is a fibrous (scarring) reaction of the lungs caused by inhalation of crystalline silica||Determine free silica content
of respirable ash
Monitor exposure in high exposure individuals and jobs
|Respiratory protective equipment|
|Foreign bodies in eyes||Conjunctivitis, corneal abrasions||Monitor wind direction and ash production for early warning to people downwind||Goggles for heavy exposure|
|Roof collapse and ashfalls from roofs||Trauma, including death||Prevent excessive accumulation of ash on roofs|
|Automobile accidents from slippery roads and poor visibility||Trauma, including death||Monitor areas that will receive ash fall and issue public announcements regarding expected conditions and road closures||Traffic control
Pre-eruption notification of what to do during an ash fall
Baxter, P.J., Ing, R., Falk, H., French, J., Stein, G.F., Bernstein, R.S., Merchant, J.A., and Allard, J., 1981, Mount St. Helens Eruptions, May 18 to June 12, 1980: an overview of the acute health impact: Journal of the American Medical Association, v. 246, n. 22, p. 2585-2589.
Baxter, P.J., Bernstein, R.S., and Buist, A.S., 1986, Health effects of volcanoes: an approach to evaluating the health effects of an environmental hazard: American Journal of Public Health, 1986, 76 (Supplement), p. 84-90.
Baxter, P.J., Bonadonna, C., Dupree, R., Hards, V.L., Kohn, S.C., Murphy, M.D., Nichols, A., Nicholson, R.A., Norton, G., Searl, A., Sparks, A.J., and Vickers, B.P., 1999, Cristobalite in volcanic ash of the Soufriere Hills Volcano, Montserrat, British West Indies: Science, v. 283, p. 1142-1145.
Blong, R.J., 1984, Volcanic hazards: a sourcebook on the effects of eruptions: Academic Press, Australia, 424 p.
Bradshaw, L., Fishwick, D., Kemp, T., Lewis, S., Rains, N., Slater, T., Pearce, N., and Crane, J., 1997, Under the volcano: fire, ash and asthma: New Zealand Medical Journal, v. 110, p. 90-91.
Hickling, J., Weinstein, P., and Woodward, A., 1999, Acute health effects of the Mount Ruapheu (New Zealand) volcanic eruption of June 1996: International Journal of Environmental Health Research, v. 9, p. 97-107.
Johnston, D. and Becker, J., 2001, Volcanic ash review—Part 1: Impacts on lifelines services and collection/disposal issues: Auckland Regional Council Technical Publication No. 44, 50 p. (see online reference).
Ronan, K.R., 1997, The effects of a "benign" disaster: symptoms of post-traumatic stress in children following a series of volcanic eruptions: Australasian Journal of Disaster and Trauma Studies. (http://www.massey.ac.nz/~trauma/issues/1997-1/ronan1.htm).
Yano, E., Higashi, H., Nishii, S., Maeda, K., and Koizumi, A., 1990, Health Effects of Volcanic Ash: A repeat Study: Archives of Environmental Health, v. 45, n. 6, p. 367-373.