SANTIAGO (Reuters) – Chilean state-owned Codelco, the world’s largest producer, said on Wednesday that it stopped its Ventanas smelter and refinery to carry out maintenance after authorities declared an environmental emergency in the region earlier in the week.

After a number of victims of sulfur dioxide poisoning in central Chilean towns, Quintero (NYSE:) Chile), Chile’s environment regulator issued interim measures to the mining company.

Codelco has taken measures to install a new temperature sensor for thermal inversion determination and also other ventilation quality indicators.

Codelco released a statement saying that to ensure proper implementation, the industrial operation will keep the voluntary suspension, which was in effect since Monday. It also advances scheduled maintenance.

“The company hopes to see clarity about who is responsible for intoxication that has affected local residents in the past days.”

Codelco said that its air quality station recorded the normal levels of sulfur dioxide concentrations on June 6. The incident was reported by Codelco. Since then, it has been stopped.

AES Chile claimed it would comply with the regulatory measures, and that the company was not responsible for the accident.

Quintero, and the surrounding area have been called a “sacrifice place” by environmental activists for each of these episodes of polluting that has led to health emergency.

There are many industrial enterprises in the town, including ENAP (the state-owned oil company) and chemicals industries.