When it comes to the amount of radon in homes, there are nine locations in Windsor that have tested higher than what's considered safe.

Connie Murphy and Lee Boufford are worried the house they're renting could be a risk to their health.

"It's something that I would really be concerned about and look into and have the house tested or the soil," said Murphy.

Murphy and Boufford are looking for any clues that could tip them off.

They said they will likely hire someone to test their home.

"It's just like a carbon monoxide detector," said Boufford. "It's there for your safety, everyone's safety."

That's where Don Beneteau, a radon measurement professional, comes in.

"We choose to do the test in the lowest living space, so usually if you're spending four hours a day in that space," he said. "Usually the basement, or a finished basement."

Radon is radioactive and invisible, but Beneteau's instruments can test for it.

"Every time one of those reactions happens in that device, it's a little plastic disc, it etches it scratches the plate," he said. "In this device they see the amount of times it's been exposed. They count the amount of etches and they calculate the exposure."

Beneteau described radon as tasteless, odourless gas that can get out of the soil and into the basement and other parts of a home.

Health Canada has guidelines for acceptable levels of radon.

Public Health Ontario and said exposure to radon gas can cause lung cancer.

Click here for CBC's interactive map of affected areas.