SANTIAGO, Chile (AP) — Chile's state-owned copper mining giant Codelco on Wednesday shut down its Ventanas copper smelter after decades of polluting Quintero Bay with toxic gases and turning it, along with 15 other companies, into what environmentalists called a “sacrifice zone.”

Eight years ago, the Chilean government declared that the three municipalities surrounding the bay — Quintero, Puchuncaví, and Concón, located 160 kilometers northwest of the Chilean capital — were saturated with fine particulate matter, inhalation of which is associated with discomfort and respiratory ailments.

During a formal ceremony held on Wednesday in Puchuncaví, images of flames from the smelter’s furnace were shown gradually diminishing until they were fully extinguished, marking the closure of the copper smelter 59 years after its founding. A Codelco refinery will continue to operate at the site.

The latest mass intoxication by pollution in the region took place only a week ago and affected nearly 100 students who suffered intoxication due to the poor air quality. An environmental alert is still in effect.

The more than 50,000 inhabitants of the bay regularly breathe in sulfur dioxide, a toxic and corrosive gas that, when inhaled, causes irritation to the nose, eyes, and throat.

More than 60% of the total sulfur dioxide emissions in the area came from the state-owned smelter, President Gabriel Boric said last year when he announced its closure.

Matías Asún, director of Greenpeace Chile, said that while the closure of Ventanas “is a very important step,” he added that “we still need to see what we'll do with the entire industrial belt that was generated around the smelter.”

The oldest company in the region is an oil terminal belonging to the state-owned National Petroleum Company, established in 1954. That was followed a decade later by the Codelco smelter and refinery and several steam and coal-fired power plants.

David Boyd, the United Nations Special Rapporteur on the Environment, said during a recent visit to the region that he “smelled the toxic fumes” and “felt them in my throat.”

Pollution incidents in the area notably began to decrease in 2019 when emissions from the industrial belt began to be regulated.