Manitoba has the highest percentage of homes testing above guidelines for radon, a cancer-causing radioactive gas.
Scientists now say radon poses more of a risk than they first thought.
They believe 16 per cent of all lung cancer deaths are caused by radon, up from 10 per cent.
Homeowners can test their homes for $50 but removing it can cost $3,000.
Winnipeg parent Beth Gillespie says it's worth it.
"I mean, I wouldn't want to stay in my house if I knew that there was a good chance that you would end up sick from living in your home," she said.
"How could you feel comfortable living in your home knowing that you could potentially die?"