Nyrstar smelter declared a “lead-in-air focus day” on Thursday to crackdown on emissions from the plant.
The company planned to shut major parts of the plant for eight hours to focus on some environmental activities.
“A big number of employees will be able to participate in activities focused on reducing and addressing emissions within the plant rather than operating plants for this time,” it said.
“Other employees will be redirected from their usual tasks to assist in this environmental focus.”
The company is thought to be reacting to lead-in-air results for Port Pirie which in some areas are the highest since 2014.
The company said it “takes its focus on the environment and the impact of our plant on the community seriously”.
“The new plant that we are ramping up will enable us to run with reduced environmental impacts,” it said.
“As we ramp-up the new plant we are also running some old plant which adds to the complexity of managing the emissions and meeting the environmental targets.
“Nyrstar has a range of plans and actions in place that have been addressing the emissions and the environmental impacts on the Port Pirie community.
“This week Nyrstar have made the decision to have a day with an additional focus on the environment and community impacts.”