Another fissure has emerged on Hawaii's Kilauea volcano, bringing the total to 21, as authorities handed out protective masks and local officials warned that toxic ash and sulfur dioxide gas are the biggest health concerns for people near the mountain.The new fissure was discovered at Leilani Estates, the neighborhood in Puna where the first new fissures were seen this month when Kilauea suddenly became more active. Since then, more than two dozen homes have been inundated in slow-moving lava flows.Hawaii News Now reports that "residents say volcanic haze across lower Puna is so thick it resembles fog, making visibility very low in some areas. About 12:30 p.m. Thursday [Hawaii time], sulfur dioxide levels in Mountain View were deemed 'unhealthy,' though officials said haze levels were declining."Scientists, the news service said, blamed the high levels of the gas on emissions from fissures in lower Puna. "Light winds meant the gases weren't pushed offshore, but lingered in communities," it said.Hawaii County officials had distributed about 2,000 N95 masks, but cautioned that they would not protect against gases and vapors.The sulfur dioxide was an immediate concern to people living near the fissures. However, the ash was ranging farther from the mountain. Winds blowing a plume emanating from crater 30,000 feet in the air were mostly directing it away from people."It was a grit, like a sand at the beach," Joe Laceby, who lives in the town of Volcano a few miles to the northeast of Kilauea's summit, tells The Associated Press about the volcanic ash.He said it was an irritant, but "not too bad."Even so, the county issued guidance to the community, noting that "the danger from this eruption is ash fallout," and adding that residents need to protect themselves from the fallout."Stay indoors with the windows closed," the guidance, reported by Hawaii Public Radio, said. "If you are in your car, keep the windows closed."The latest explosion at Kilauea's summit came shortly after 4 a.m. Hawaii time on Thursday.The AP writes: "Geologists have warned that the volcano could become even more violent, with increasing ash production and the potential that future blasts could hurl boulders the size of cows from the summit." Copyright 2018 NPR. To see more, visit http://www.npr.org/.