PUERTO MONTT, Chile (CNN) -- Nearly a week after a volcano erupted in Chaiten, Chile, disgorging its contents across a wide area of the Andes Mountains, authorities finished evacuating the area most affected.
Though the eruption has been continuous, it increased at midnight Wednesday, powered by a massive explosion, then returned to its steady discharge of ash, officials said.
Overnight, authorities armed with a court order evacuated the last of the holdouts -- many of whom had sought to remain to care for their cattle -- among the approximately 5,000 residents inside the 30-kilometer (18-mile) exclusion zone, said Carmen Fernandez, director of Chile's Office of Emergency.
By Thursday morning, about 100 people -- primarily police, military and journalists -- remained in the immediate vicinity of the volcano, she said.
In Bariloche, 300 kilometers (186 miles) from the volcano, Chilean Minister of Defense Jose Goni met Thursday with Argentine Vice President Julio Cobos to coordinate the transfer of the cows in the affected zone to Argentine territory, 60 kilometers (37 miles) away.
Many of Bariloche's residents clutched handkerchiefs to their faces or wore cloth masks -- handed out by the government -- as they went about their business. Even with the masks, breathing could be difficult.
Thick layers of ash covered everything like freshly fallen snow.
Bariloche's airport and other regional airports were shut Thursday after satellite photos revealed that the air over the provinces of Buenos Aires, La Pampa, Rio Negro, Neuquen and Chubut was filled with ash.
The most dense clouds of the material were seen over Chubut and Rio Negro, with lesser amounts in the other provinces. In all, clouds of ash covered nearly a third of Argentina, the country's meteorological service said.
As of noon Thursday, ash could be seen in the sky above Buenos Aires and its suburbs, it said. "The sky appears gray, products of the presence of ashes that are moving from west to east at an altitude of about 3,500 meters," the service said. 
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"Fortunately, the composition of the ash, air and smoke that is coming out of the volcano isn't highly toxic," said Mirta Roses, director of the Pan American Health Organization.
But, she said, children, older people and people with allergies or asthma are at highest risk and should make extra efforts to avoid it.
Many of the evacuees were taken to Puerto Montt, a port city in southern Chile about 200 kilometers (124 miles) north of Chaiten.
The volcano, which is about 1210 kilometers (752 miles) south of the Chilean capital, Santiago, began erupting early Friday, raining gray ash onto Chaiten. The small city is on the Corcovado Gulf, in southern Chile.
The volcano last erupted around 7,420 B.C., according to the Smithsonian's Global Volcanism Project.
Chile contains a large number of active volcanoes, including Llaima, which erupted in January, sending lava and smoke down a snow-covered mountain.
CNN en Espanol's Alberto Pando contributed to this story
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