Connie Neyedly, who has three children attending P.J. Gillen school in Esterhazy, said she is worried her children's health is at risk.
"To drop them off and knowing that windows and fresh air are not in that school ... it upsets me as a parent," she said.
The NDP raised the case in Monday's question period, calling it an example of schools that are in disrepair across the province.
The public health region said in a report last month that carbon dioxide levels at the southeastern Saskatchewan school measured more than 4,000 parts per million in one room — the recommended concentration is below 1,000.
The air ducts in the school have been sealed off because of mould and electric heaters are being used as a temporary solution, causing carbon dioxide levels to increase.
Niel Knezacek has an eight-year-old son at the school and a five-year-old daughter he expects to sent there next year. He said the school is often too cold, with temperatures dropping to below 15 C on some days.
"How many days are you going to go to work, put on a jacket and work on a computer? It's not going to work," he said. "Why do we expect a five-year-old to do the same?"
He said parents were asked to bundle up their children for the school day.
"I should be worried about my kids falling behind, but right now I'm worried about my kids finishing that school and being healthy," he said.
Education Minister Don Morgan said the school will be outfitted with a new system of natural gas heaters that will also filter in fresh air, costing around $1.3 million. He said the province will provide $800,000 and is asking the school division to fund the remaining amount.
"We learned about this a while ago," he said, adding that he credits the school division for implementing a temporary solution. "The problem with electric heaters is there is no fresh air being brought in, no method of exhausting ... the kids became sleepy and groggy."
He added that while the carbon dioxide levels are acceptable, "that's no way to learn."
The plan is to install the new system after the school year ends so that it's ready for the fall, he added.
"We don't want to close the school, we don't want to relocate, we are now into some warmer weather," he said. "We want to address it as quickly as we can."
The Opposition has repeatedly criticized the state of Saskatchewan's schools.
NDP Leader Cam Broten cited a $1.5-billion deficit in school maintenance and repair.
"It's only when they think there is some political fallout that they start to take this seriously," he said.
Broten added that there isn't a detailed list of schools in need of repairs available to the public, calling it a lack of transparency.
"I think parents deserve to know the state of the schools their kids are going to," he said.
Knezacek said his son often has a stuffy nose, and he monitors him to see if there are signs of headaches or dizziness.
"We're assuming it's because of the air quality in the school," he said. "It's very frustrating."