The largest volcanic eruption in over two centuries is underway in Iceland and its spewing dangerous amounts of carbon and sulfur dioxides into the atmosphere.
Lava from the Holuhraun volcano has been bubbling up from the ground since August and has spread out over an area larger than Manhattan. Not since the Laki eruption in 1783, which killed nearly a quarter of the Icelandic population, has Iceland seen such a significant volcanic event.
The volcano's remote location in country's northeast has minimized the public health impacts, but volcano experts predict its likely to remain active, which could put more people at risk.
"The sulfur is what causes most of the respiratory issues," Erik Klemetti, a geoscientist at Denison University in Ohio, told VICE News. "When you mix it with water you can get acid rain and burning in your eyes and throat even if you're fairly far away."
Iceland's Environment Department is measuring sulfur dioxide levels at more than 20 stations across the country. In some areas, the levels have exceeded 24-hour exposure limits by more than 15-fold.
Authorities have set a safe exposure level at 125 micrograms per cubic meter over 24 hours and 350 micrograms for a one-hour. In Reydarfjordur, in eastern Iceland, sulfur dioxide levels reached about 2,100 micrograms shortly after the eruption.
Sulfur dioxide can cause difficulty breathing and irritation of the skin, eyes, and throat. People with respiratory diseases, such as asthma and emphysema, and heart disease are more likely to be affected by the concentrations, according to the Iceland Directorate of Health.
The Icelandic Met Office has published daily alerts of areas where high concentrations of sulfur dioxide are expected. In eastern Iceland, schools have closed and asthma drug sales have increased.
"The gas is mostly an issue for north and east of the eruption," Einat Lev, a volcanologist at the Lamont-Doherty Earth Observatory at Columbia University, told VICE News. "It's a very sparsely populated area, but if anyone is there it's an issue."
Holuhraun is not what one typically imagines as a volcano. The lava erupts from a fissure in the ground, flowing along river channels and forming a new layer on the charred, black lava field.
Such eruptions are common in Iceland and have been taking place for millions of years. Even though the current eruption is large on a human time scale — it's nearly seven times larger than the infamous Eyjfjallajokull eruption that caused the cancellation of more than 100,000 flights in 2010 — it's relatively small compared to some that have taken place over the last few millennia, Klemetti said.
The Laki eruption in 1783 was more than 10 times larger than the current Holuhraun eruption, killing 10,000 people in Iceland. An additional 20,000 people died in England when the huge amounts of sulfur released in the eruption exacerbated an unusually hot summer.
But if the eruption continues into spring, the problems could extend beyond health concerns. When sulfur mixes with water, it turns to sulfuric acid, which could rain down on plants and crops and cause damage.
"There's still earthquakes going on there, which implies that there's more magma coming up," Klemetti told VICE News. "It doesn't right now show any signs that it's going to be ending anytime soon."
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