The eruption of Kilauea volcano in Hawaii sparked new safety warnings about toxic gas on the Big Island's southern coastline after lava began flowing into the ocean and setting off a chemical reaction.

The molten rock began pouring into the sea over the weekend. It's been generating plumes of lava haze or "laze" as it interacts with seawater.

The lava is also threatening a nearby geothermal plant. A warehouse close to the Puna Geothermal site was destroyed by lava late Monday, and workers on Tuesday were racing to cap off production wells at the site to prevent the release of toxic gases.

The plant harnesses heat and steam from the Earth's core to spin turbines to generate power, providing for about 25 per cent of the island's daily energy demand. Earlier this month, officials removed 190,000 litres of toxic gas from the plant to reduce the chance of explosions.

Lava entered the property on Monday and was still flowing slowly by midday Tuesday.

The weeks-old eruption has generated earthquakes and produced gushing molten rock, giant ash plumes and sulphur dioxide. It has destroyed more than 40 buildings and forced more than 2,000 people out of their homes.

Here are key things to know about the latest volcanic threats:

A photographer records lava erupting from a fissure in Kapoho, Hawaii, on Monday. (Jae C. Hong/Associated Press)

What is lava haze?

It is made of dense white clouds of steam, toxic gas and tiny shards of volcanic glass. Janet Babb, a geologist with the Hawaiian Volcano Observatory, says the plume "looks innocuous, but it's not."

How is it created?

Laze is formed when lava enters the ocean and triggers a series of chemical reactions.

The seawater cools the lava, which forms a glass that then shatters. Tiny pieces are picked up by the steam cloud, which contains hydrochloric acid created by the interaction of lava and the ocean.

Lava from Hawaii's erupting Mount Kilauea volcano is pouring into the ocean and continues to break up roads on the way 0:44

"Just like if you drop a glass on your kitchen floor, there's some large pieces and there are some very, very tiny pieces," Babb said. "These little tiny pieces are the ones that can get wafted up in that steam plume."

Scientists call the glass Limu O Pele, or Pele's seaweed, named after the Hawaiian goddess of volcano and fire.

Why is it dangerous?

The clouds contain hydrochloric acid, which is about as corrosive as diluted battery acid. It can irritate the skin and eyes and cause breathing problems.

Babb says protective masks that officials have been distributing to protect people from volcanic ash will filter particles from lava haze but not the hydrochloric acid.

The Kilauea volcano is oozing, spewing and exploding on Hawaii's Big Island. The eruptions have become more hazardous in recent days, with rivers of molten rock pouring into the ocean and flying lava causing the first major injury. (Jae C. Hong/Associated Press)

Laze itself is not enough to cause serious burns, Babb said, unless someone is right on top of where lava enters the ocean. Waves can wash over molten lava and send scalding water onshore, so people should maintain a safe distance.

No major injuries have been reported from lava haze. The U.S. Geological Survey says laze contributed to two deaths in 2000, when seawater washed across recent and active lava flows.

Who needs to be concerned?

Mostly people who are near the lava entry on the southern coast, either on land or in boats just offshore. Where the plume wafts depends heavily on wind direction and speed.

The gas clouds initially appear on the shoreline, but trade winds on Sunday carried plumes about 24 kilometres to the southwest. The cloud was offshore, running parallel to the coast.

Lava flows near a house on the outskirts of Pahoa in Hawaii. More than 2,000 people have been forced from their homes during the last few weeks of eruptions. (Terray Sylvester/Reuters)

When the winds die down, the plume can flatten out. Its size depends on the volume of lava falling into the sea.

The hazards minimize once the shards fall to the ground because glass mixes with the earth.

Lava continues to flow on Hawaii's Big Island, bubbling as it travels toward the coast, destroying everything in its path 1:13

What other threats are there?

Methane explosions could be a problem as lava flows into areas with a lot of vegetation. Babb said decaying vegetation creates pockets of methane, which the lava's heat can ignite.