Health Canada has found radon gas at dangerous levels in more than 23 per cent of Manitoba homes, marking the highest rate among provinces and territories.
The high levels have been primarily found in south parts of the province, including Winnipeg, Brandon and Riding Mountain areas.
Experts are pushing for more testing.
"What we want people to know is it doesn't really matter where you live, it's important for all Canadians to be testing," said Eveline Schroth from Health Canada
According to Health Canada, radon doubles the risk for developing lung cancer and is the second leading cause, after smoking.
Radon comes from uranium in the ground and seeps into homes, where it can become trapped.
"It's odourless, colourless," said John Hockman, a radon researcher.
Experts say people can pick up a radon test kit at home renovation stores for about $60. People are advised to do the three-month long test during the winter to find out if a home is in the danger zone for radon levels. Health Canada said if your home has central air, you can also test for radon in the summer by making sure windows are closed for three months.
The Canadian Cancer Society said it's concerned not enough people are testing for the gas.
"It is a challenge to get the message out there for some reason. It hasn't gotten the attention it deserves," said Jason Permanand from the Canadian Cancer Society.
Harry Strub found high levels of radon in his home 23 years ago. His family spent about $1,500 on a system to bring radon levels down to nearly nothing inside the house.
At the time, Strub only guessed that radon wasn't safe, but his family acted swiftly to have the system installed.
"We were scared. We operated out of fear. We operated impulsively," said Strub.
Beginning on Apr. 1, Manitoba's building code will require all new homes to have radon mitigation measures built in. The issue doesn't just affect basement areas as a furnace or central air system can circulate radon through a home.
Harry Johnson has made a business out of radon mitigation. He said the key to preserving a person's health is finding out if there's a radon problem inside a home.
"I need to assure people, we know what the fix is for this. There are proven techniques," said Johnson.
The province is testing radon levels in government buildings such as schools and Manitoba Housing Units.
It has promised to create an action plan by early summer that will include an education campaign.
According to Manitoba Health, the radon levels in Manitoba haven't translated into higher lung cancer rates, with rates similar here to elsewhere in Canada.
- with a report from CTV's Laura Lowe
