The Health Risks Posed by Icelands Volcano

On March 20, 2010, Eyjafjallajokull (pronounced AY-uh-fiat-luh-YEU-koot-luh, with the ‘EU’ as in liqueur) broke nearly 200 years of dormancy with its first eruption since 1821, releasing a cloud of ash, gas, and water vapor in addition to a small flow of lava. A second, larger eruptive cycle began on April 15, during which the Eyjafjallajokull volcano has spewed out an ash cloud that has at times spread over most of Europe and part of North America. However, most of the health risks from both sets of eruptions have thus far been confined to Iceland.


All Hekla-type eruptions are high in water-soluble fluorides, which are poisonous to livestock and to people who consume the products of that livestock. Foraging livestock, such as sheep, are the most vulnerable, with symptoms of skeletal fluoridosis beginning at just 25 ppm. At 250 ppm and higher, livestock foraging on contaminated feed will die within a few days.

In the current Eyjafjallajokull eruptions, high fluorine release has so far been confined to parts of Iceland which are downwind of the volcano. The closest farmers have already been evacuated due to Eyjafjallajokull’s explosive potential. Other Icelandic farmers in the area have been warned not to allow their livestock to graze on land downwind from the volcano, even if it is not covered with ash.

Fluoride release is much higher in Hekla-type eruptions when there is also lava release. The March eruption was higher in fluoride content than the explosive April eruptions. At the same time, the Eyjafjallajokull volcano has much more violent eruptions when there is little or no lava release. This means that the Eyjafjallajokull eruptions are unlikely to spread fluorides beyond Iceland.


Neither sulfur dioxide nor hydrogen sulfide has yet been measured in substantial amounts during the current Eyjafjallajokull eruptions. However, records from previous Eyjafjallajokull eruptions mention the strong smell of sulfur in the air.

Sulfur dioxide is a common component of volcanic ash. It is associated with overall breathing difficulty, as well as an increased risk of respiratory illness and premature death. It is also a primary cause of acid rain.

Hydrogen sulfide is poisonous at around 300 ppm, and anything over 800 ppm can be quickly lethal. Fortunately, its familiar rotten egg smell can be detected by the human nose at just 0.0047 ppm. Health issues due to hydrogen sulfide are of 2 general types: caustic damage, and systemic damage.

Caustic effects consist of damage due to tissue irritation. Eye irritation begins at around 10-20 ppm, while higher concentrations can cause permanent eye damage. Other caustic health effects of hydrogen sulfide include sore throat, cough, nausea, loss of appetite, headaches, and fluid in the lungs. In most cases, these effects clear up within a few weeks once the hydrogen sulfide is removed.

Systemic effects are usually linked with chronic, long-term exposure to hydrogen sulfide, which could happen if the Eyjafjallajokull volcano continues to erupt for months or years. Nervous system damage can cause poor memory, dizziness, and overstimulation of the central nervous system. Endocrine system damage has been linked to increased miscarriage and reproductive health issues.

At around 100 ppm, the olfactory nerve is paralyzed, resulting in temporary loss of smell. This can be dangerous, since the rotten egg smell is the human body’s best warning system.

Particulate matter

The particulate matter in volcanic ash is what causes those brilliant sunsets. However, high levels of particulate matter in the atmosphere also cause health problems, just the same as regular air pollution. Smaller particulate matter is more damaging than larger pieces, which are usually filtered out before they cause much more than a sneeze.

Lung disease, such as asthma and lung cancer, is aggravated by particulate matter and in some cases may be caused by it. High particulate counts have also been linked to high plaque deposits in arteries. Particularly sharp particular matter also causes skin and eye irritation.

The largest explosive eruptions have the lowest health risks from particulate matter. Although the ash plume is carried further, most of the ash is ejected high into the atmosphere, where it disperses naturally over time.

Silicon dioxide (silica)

Although up to 58% of the ash in the April eruption is silicon dioxide, those inhaling it will not develop silicosis. Silicosis can only be developed through exposure to crystalline silica dust. The silicon dioxide in Eyjafjallajokull’s ash is not crystalline. This is because when silicon dioxide is heated to the melting point and then suddenly cooled in the upper atmosphere, it becomes millions of tiny glass shards, which destroys all crystal structure.

However, the high glass content of such plumes makes the ash sharp and abrasive, which can cause the same effects as particulate matter. During the 1821 eruption, Eyjafjallajokull ash caused local eye problems due to the constant irritation. If it can sandblast aircraft, think what it can do to your skin and lungs!