LA PALMA, Canary Islands – A huge cloud of ash prevented flights to and from the Spanish island of La Palma on Sunday as molten rock continued to be thrown into the air by an erupting volcano.

No flights arrived or departed, although rescuers cleaned up the ashes from the airport runway.

Islanders faced a mixed picture of good news and bad news, with some evacuees allowed to return home amid low seismic activity as authorities took stock of the damage. Around 430 buildings have been destroyed so far in the countryside.

La Palma volcano, which is part of the volcanic Canary Islands off northwest Africa and is home to around 85,000 people, erupted on September 19. Rapid evacuations of more than 6,000 people prevented casualties.

Life on the rest of La Palma, which is approximately 35 kilometers (22 miles) long and 20 kilometers (12 miles) wide at its widest point, has remained largely unaffected.

“We are not in a state of total alarm,” the technical director of the volcanic emergency response unit, Miguel Ángel Morcuende, told a press conference. “Life on the island continues, although those close to the eruption face challenges.”

The volcano’s mouth was still ejecting flaming molten rock and spitting black smoke. His roar could be heard for miles. Scientists say the rash could last up to three months.

The sound of volcanic explosions can shatter glass in the surrounding area, Morcuende said, urging people living within 5 kilometers (3 miles) to stay away from their windows.

Officials said the falling volcanic ash was not a threat to public health, but the cleanup can be dangerous for people’s lungs and eyes. They urged people to wear face masks, gloves and goggles, as well as long-sleeved pants and shirts, when disposing of the ash.

Some 25,000 metric tons of sulfur dioxide are emitted from the crater every day, but do not pose a health threat, officials said.

Although Spain’s Aena airport authority tweeted that La Palma airport was back in operation on Sunday, no planes were scheduled to land or take off. Five airlines had already canceled their flights for the day to La Palma because of the ash cloud. Volcanic ash is dangerous for aircraft engines.

Long queues formed at the port of the island to take the ferries off the island.

Authorities allowed 160 evacuees to return to their homes and allowed other evacuees to collect their belongings from their homes, as the lava flows remained slow.

The lava is 2 kilometers from the coast, Morcuende said. Two rivers of lava slide down the hills: one is further north, where molten rock from a new fissure extends over an area where lava spread and hardened last week, and another to the south which advances at 30 meters (about 100 feet) per hour. The temperature of the lava is approximately 1,250 degrees Celsius (2,282 degrees Fahrenheit).

Pope Francis said on Sunday that he was praying for all those affected by the volcano, dedicating a prayer to them at the end of his weekly noon blessing in St. Peter’s Square.

“I am thinking above all of those who have been forced to leave their homes,” said the pontiff.

This month’s eruption is the first on La Palma since 1971.