Buying a radon monitor? How to make sure you purchase one that actually works

Anyone hoping to check their home’s radon level can now pick from dozens of different radon monitors sold online or in stores — but experts warn many of those devices don’t actually work.

Plenty of Canadians install faulty monitors, only to find out later that they aren’t approved or certified, cautioned Pam Warkentin, the executive director of the Canadian Association of Radon Scientists and Technologists (CARST), which runs the country's certification program alongside Health Canada.

“I have to tell them that they can’t really base any decisions on those detectors and need to go purchase another one."

Wasted money and time add up fast. Electronic monitors can be hundreds of dollars each, and people are encouraged to test for a minimum of three months. Warkentin recalled speaking to one homeowner who purchased devices for himself and his adult children, but only learned they had been recalled until after he’d used his own monitor for several months.

Those kinds of “scam” devices pose a public health risk since they don’t show a building’s actual radon level, Warkentin added. 

She said misleading readings can discourage homeowners from taking steps to reduce household radon, an invisible, radioactive gas that can cause lung cancer through long-term exposure. Millions of Canadian homes likely have high levels, research shows, while radon-induced lung cancer is thought to kill an estimated 3,200 people each year.

“Many people are going to be testing and have a low level and not even question the device,” Warkentin warned.

So how do you properly test your home for radon? And what monitors should you avoid?

Health Canada recommends testing your home for three months or more, and ideally during the winter months when homes are sealed up and radon readings can be highest.

“There's no way to predict it,” said Warkentin, who is also a project manager for Canada’s Take Action On Radon awareness program. “Everybody just needs to test.”

To do that long-term testing, you can either hire a radon measurement professional or get your own test kit.

Some communities provide free radon monitors through libraries or local public health units, but typically, homeowners end up paying out of pocket for their own devices. And there are a wide variety of options out there, ranging from passive tracking devices to electronic monitors that display real-time results on screens and apps.

The issue, Warkentin said, with some devices is they simply don't work, instead providing "false low" readings.

"I don't know what they're reading, but they're not reading the radon level," she said. "So they're giving you a number, but it's not based on ... what the radon level in the home [actually] is."