Officials on the Big Island of Hawaii say some vents formed by Kilauea volcano are releasing such high levels of sulfur dioxide that the gas poses an immediate danger to anyone nearby.

Hawaii County Civil Defense said Monday the gas may cause choking. It says people may be unable to breathe if exposed.

The county says the warnings apply to an area near the vents in the southeast section of the Lanipuna Gardens neighbourhood and surrounding farm lots.

Authorities recommend leaving the area and seeking medical attention if severely affected.

Officials have ordered evacuations for about 2,000 people since Kilauea volcano began shooting lava into a residential neighbourhood on May 3.

The eruptions have opened nearly 20 vents in the ground. Lava has destroyed more than 40 structures, including two dozen homes.

A new fissure in Hawaii’s Puna District sent gases and lava exploding into the air, spurring officials to call for more evacuations as residents waited for a possible major eruption at Kilauea volcano’s summit.

Officials say the pace of bookings for hotels and tour activities on the Big Island of Hawaii are down about 50 percent compared with previous years as an erupting volcano spews lava for the second week.

The Big Island tourism board estimates $5 million worth of cancellations from May through July. There was “an immediate impact” after the Kilauea volcano first erupted on May 3.

Tourism on the island brought in $2.5 billion in revenue last year. Board executive director Ross Birch says this is the “first leak we’re seeing out of the bucket.”

Authorities say the volcano has produced nearly 20 active lava fissures and destroyed more than two dozen homes.

The National Weather Service has warned residents of “light ashfall” throughout the day in the island’s southernmost district after a burst of volcanic emissions.

Another new volcanic fissure has formed as the Kilauea volcano on Hawaii’s Big Island continues to erupt and lava from another fissure is carving a channel toward the ocean.

The new eruption was reported Monday in the Lanipuna Gardens subdivision, an area that has already been evacuated. Civil defence officials warn of volcanic gas emissions and active eruptions with this new fissure.

A separate fissure is still active after it formed on Sunday. The Hawaiian Volcano Observatory says a lava flow has now formed and is slowly moving toward the ocean, which is about two miles (3.2 kilometers) away. No homes or roadways are threatened by this flow.

Kilauea began erupting on May 3. Since then, fissures have been generated mostly in Leilani Estates subdivision, where nearly 2,000 residents were ordered to evacuate. Lava has destroyed more than 40 structures, including two dozen homes.

Geologists warn that Kilauea’s summit could have an explosive steam eruption that would hurl huge rocks and ash miles into the sky.

Hawaii County Civil Defense issued an emergency cellphone alert after the fissure was discovered early Sunday morning.

The agency says one “unidentified structure” was destroyed by the new vent, bringing the total number of homes and other buildings lost to lava to nearly 40.

Residents living near the fissure were told to evacuate and two nearby community centres were serving as shelters for people and pets.

Lava spread across hundreds of yards (meters) of private land and loud explosions rocked the neighbourhood not far from the Leilani Estates subdivision, where more than a dozen other active vents opened over the past week.