Lava spilling off the southeastern edge of the island of Hawaii is producing a noxious haze where it hits the seawater. Made out of hydrochloric acid, steam, and shards of volcanic glass, the gas is hazardous to anyone who breathes it. But while the mixture is dangerous, it shouldn’t put many people in danger.
The noxious fumes are called “laze,” which volcano experts say is way less peaceful than it sounds. The stuff forms when lava hits the cool ocean, almost like water on sauna rocks — if the steam that sizzled off had acid and glass in it. The more lava, the more laze. But this isn’t the first time we’ve seen laze floating over a spot on Hawaii’s coast, according to Robin Andrews for IFL Science. So scientists have had time to study it. “We know it’s a hazard to people who are right in the thick of it, so it’s important to stay clear of it,” says volcanologist Michael Poland with the US Geological Survey.
Most people have left the area because of the lava, Poland says. “It’s a few kilometers before you get to any sort of residential area that’s still occupied, and at that point it should dissipate,” he says. So the people who are most likely to be exposed are the geologists and emergency managers working in the area — who are trained to avoid the laze — or tourists who shouldn’t be there, he says. For sightseers, he says, “This is a completely avoidable hazard.”
Laze forms when lava reaching temperatures of around 2,100 degrees Fahrenheit strikes seawater. The heat boils seawater dry — not just boiling away the water, but also heating salt molecules the boiled water leaves behind, like magnesium chloride. “The magnesium chloride is pretty reactive,” says volcanologist Simon Carn at Michigan Technological University. “It reacts with the water — the steam in the air.” That makes hydrochloric acid, which probably sounds familiar because it’s the acid in your stomach that melts the food you eat into a soupy pulp. That stuff isn’t good to get in your lungs.
It gets worse, because the reaction works both ways, Poland says. “So the lava is boiling the sea, but the sea is also cooling the lava,” he says. “It becomes volcanic glass, and then it shatters and these little particles of glass get wafted up in this hot steam and acid plume.” Together, those ingredients create a steam-hot blend of airborne hazards that’s dangerous to breathe or get in your eyes.
Your best bet is to just steer clear of it, Poland says. Laze tends to be a problem mainly where it’s being produced, and it doesn’t travel far before clean air blows the plume apart. If a few tendrils of laze catch you, “It’s not going to hit you and your skin starts melting,” Poland says. Still, to be clear, “If you’re in that plume, it’s not going to be good for your health,” he says. Get too close, and it can even be deadly: laze caused two deaths in 2000, according to the USGS.
So unless you’re a highly trained scientist, don’t go gawp at where the lava strikes the sea. There are other reasons to avoid that spot, anyway. For one thing, the lava flowing off the island starts building up new land, Poland says. The skirt that forms along the edge of the island looks like a river delta made of lava, and it gets bigger, and bigger, as the lava keeps flowing. But this new land — resting on sand, and pummeled by waves — is unstable. Sometimes these deltas fail in huge collapses, and sometimes they break apart bit by bit, Poland says.
When this delta of lava cracks apart, hot rock meets cold water and can explode — launching projectiles into the air. The small collapses can also cause rogue waves that could sweep away someone standing too close to the water.
“It’s not a safe environment,” Poland says. “It can be enjoyed from a distance, but it’s not something you want to get up close and personal to. There are too many hazards.”