Hawaii residents dealing with Kilauea’s volcanic eruption are facing a potentially deadly new challenge as lava that has reached the Pacific Ocean threatens to send up laze, a hazardous mix of glass particles and noxious gas. 

The new challenge came when a stream of lava from the volcano cut through Highway 137 on the south coast of Hawaii’s Big Island late on Sunday and poured into the sea, authorities said.

The mix of erupting lava, which can reach a blistering 1100 degrees, and sea water could send up plumes of laze, a mix of hydrochloric acid, steam and volcanic glass particles, Hawaii County Civil Defense said in a statement.

“Be aware of the laze hazard and stay away from any ocean plume,” the agency said, warning that potential hazards include lung damage.

A steam plume rises from lava entering the Pacific Ocean on Hawaii’s Big Island on Sunday. Photo: Getty

Laze – a combination of “lava” and “haze” – killed two people in 2000 when a lava flow reached the coast, and even a wisp can irritate eyes and lungs and make it hard to breath, the US Geological Survey said.

Acid rain from laze has a pH, a measure of a substance’s acidity or baseness, of between 1.5 and 3.5 and “has the corrosive properties of dilute battery acid,” the agency said.

The public was warned to stay away from potential plumes of laze near where the lava is flowing into the ocean off Highway 137 near a state park.

An air quality index for Kona, about 64km northwest of the eruption site, was at “orange” level, meaning sensitive groups, such as older people and those with lung disease, could be affected.

A young resident keeps an eye on erupting lava near her home in Kapoho. Photo: Getty

Kilauea, one of the world’s most active volcanoes, has destroyed dozens of homes and sent thousands of residents fleeing as at least 22 volcanic vents have opened up since the latest upheaval began on May 3.

Besides lava, the cracks have spewed life-threatening levels of toxic sulphur dioxide gas.

A stream of lava is now blocking a Hawaii highway serving as an escape route for coastal residents, while the first known serious injury has also been reported.

A home owner on a third-floor balcony had his leg shattered from shin to foot when hit by lava spatter, said Janet Snyder, a spokesperson for the Office of the Mayor, County of Hawaii.

As magma destroyed four more homes, molten rock from two huge cracks merged into a single stream, threatening to block other escape routes and touching off brush fires.

The erupting lava crossed Highway 137 shortly before midnight local time.