In 2009, Donna Schmidt died of lung cancer. By the time she noticed symptoms and was diagnosed, the cancer had spread from her lung to her spine, liver, breast, bone and brain. She wrote a blog chronicling her last few months in treatment, signing her last post off with, “Thanks to all for everything you have given me.”

Schmidt had smoked earlier in her life, but had quit 20 years before her diagnosis. Trying to make sense of the tragedy, her husband, Dana, delved into research and news articles about lung cancer. “The word radon came up with Castlegar [British Columbia], where we lived for 15 years,” he remembers. When he tested his former house, the results revealed the concentration of radon gas in the house averaged around 400 becquerels per cubic metre (Bq/m³). Health Canada recommends that people who live in homes that test above 200 Bq/m³ take action to reduce the levels of radon gas entering the home. Venting systems can effectively bring radon gas to very low levels if installed properly.

Jing Chen, of the Radiation Protection Bureau of Health Canada, recently estimated that radon gas is responsible for 16% of lung cancer deaths in Canada, making it the second-biggest cause of lung cancer next to smoking. According to her analysis, radon gas kills 3,261 people in this country a year.

For several years now, groups like the Cancer Society, the national and provincial Lung Associations and the Radiation Safety Institute of Canada (RSIC) have been raising awareness of the harms of radon gas through media interviews and public outreach. Their efforts increase in November, which is Radon Action Month. The groups are supported by Health Canada, which has a radon outreach budget of $550,000 a year.

Still, most Canadians don’t know they should test for radon gas. A survey commissioned by the Canadian Cancer Society in late 2014 found that 96% of Canadian respondents hadn’t tested their homes for radon. Only one in three of those surveyed were aware that radon gas can cause lung cancer.

Some radon experts think raising awareness isn’t enough and are calling for more legislation that would require testing. After all, there are ways to bring the level of radon down if it’s high. Currently, “it’s like the Wild West,” says Bob Wood, president of the Canadian Association of Radon Scientists and Technologists (CARST), with little legislation to protect Canadians from radon gas exposure.

What is radon gas and what does the evidence say about who’s at risk?

Radon gas is invisible and odorless, so the only way people know the concentration of gas in their home is by testing. A product of the breakdown of uranium, radon gas comes from the soil and enters a home through cracks or openings in the foundation, floor drains and pipes.

Most people exposed to radon gas in homes aren’t harmed by it. In rare cases, however, particles from radon gas damage cells in the lung and lead to cancer. There is currently no evidence linking radon exposure with any other health issues aside from lung cancer.

A review of 13 controlled studies in Europe found that the lifetime risk of developing lung cancer would be 0.4%, supposing no exposure to radon gas. For smokers, taking radon gas out of the equation, the lifetime risk of lung cancer is 10%.

For people exposed to indoor radon gas concentrations at 100 Bq/m³, the lifetime exposure risk of lung cancer increases to 0.5% and 12%, for non-smokers and smokers respectively. And for those exposed to radon gas at concentrations of 800 Bq/m³, the lifetime risk jumps to 1% for non-smokers and 22% for smokers.

Most people in Canada live in homes that have radon gas concentrations below 200 Bq/m³, according to a Health Canada survey of approximately 14,000 homes conducted over 2009 to 2011. But 7% of the randomly tested homes were found to have radon gas exposures above this level. With the exception of Nunavut, homes with radon gas levels above 200 Bq/m³ were found in every province and territory. New Brunswick had the highest proportion of homes testing above the cut-off, with 25% of homes found to have high radon, followed by Manitoba. This is due to higher average concentrations of underground uranium in these provinces, but “there are pockets” of high uranium concentration throughout the country, explains Steven Mahoney, president and CEO of the Radiation Safety Institute of Canada.

Even in areas low in underground uranium, the type of soil beneath a home, as well as the number of cracks or openings in a home’s foundation, all impact a home’s radon gas levels. “Even if your neighbor has low levels you might have high levels,” explains Robert Nuttall, assistant director of the cancer control policy at the Canadian Cancer Society.

Those who live in basement apartments or spend most of their time in basements are especially at risk because radon gas is heavy and is found in the highest concentrations in basements. For this reason, the U.S. Environmental Protection Agency recommends testing only for all homes below the third floor.

Regulations need to better protect Canadians from radon gas

Currently, it’s up to individuals to learn about radon and decide if they want to buy a testing kit. Health Canada doesn’t require home owners to make radon tests a condition of selling a home. According to Andre Gagnon, media relations officer for Health Canada, that’s because “radon testing during a real estate transaction…would typically not allow for a long-term three-month test.” (While short term tests are available, and can be requested by individual buyers, they don’t always provide a representative reading because radon levels in a house fluctuate – the concentration tends to be higher in winter, for instance, when windows are closed.)  Wood says his organization is currently researching to see if a short-term test could be used to provide a reasonable picture of radon concentration in a home.

In the meantime, CARST, along with RSIC, are calling on the Ontario government to require owners of basement apartments to do long term radon testing. “We looked at what the government could do that would have the biggest bang with low cost to the government,” says Wood, noting that long-term testing devices cost around $30. (The cost of mitigating a house found to be high in radon is estimated between $1,500 and $3,000.) No provincial government or territory currently requires the testing of basement apartments.

In addition to targeting basement apartments, other regulations being pursued involve provincial buildings and workplaces. To protect employees, most provinces have adopted the Canadian Guidelines for the Management of Naturally Occurring Radioactive Materials, which state that full-time workers should not be exposed to radon levels above 200 Bq/m³. However, testing of workplaces is not enforced, explains Wood. In Ontario, for instance, it’s up to employees to request a radon test result, and if the employer refuses, a work refusal may be the only solution. “The Ministry of Labour gets involved in the case of a work refusal and could make an order to get the workplace checked,” says Wood.

Bill 11, which is currently sitting in Committee in Ontario Legislature, would mandate testing of workplaces and public buildings, and also require the government to educate Ontarians on the importance of testing. But Mahoney doesn’t have high hopes for the bill. “It’s gone through first and second reading three times in the past and it’s currently waiting a slow and painful death,” he says. He believes the bill isn’t getting high priority because it’s a private member’s bill, rather than a government bill, and because testing of provincial buildings alone could cost $20 million.

The cost is not insurmountable, however. Quebec requires all public schools to test radon levels. In that province, at least 10% of schools have had at least one classroom test high in radon, says Wood, with mitigation efforts completed or underway to divert the radon gas out of the building.

Barb MacKinnon, president and CEO of the New Brunswick Lung Association, says her organization is also calling for mandatory testing requirements for provincially owned buildings and workplaces, in addition to changes in the federal income tax law that would make renovating homes high in radon tax deductible.

Are changes in building codes the answer?

Here’s the complicated part. According to research by Health Canada, even if testing and mitigation regulations ensured that no Canadian was exposed to radon gas concentrations above 200 Bq/m³, that would only prevent 927 of the 3,261 deaths caused by radon gas annually.

That’s because more than 93% of Canadians are being exposed to levels of radon gas below 200 Bq/m³, and spread across a big population, even that low-level exposure is causing lung cancer deaths. “There’s no level of exposure that is without any risk,” explains Ray Copes, chief of environmental and occupational health at Public Health Ontario.

For this reason, Copes recommends changing building codes such that radon gas levels in homes would be closer to the outside concentration, of around five to 15 Bq/m³.

BC recently amended its building code to require homes in most of the province to install such a venting system. Ontario’s building code requires one town and two townships in the province to build in radon-reducing piping and fans. Alberta’s code, meanwhile, mandates that homes have a “rough in” that would make it simple and cost-effective to install a radon-venting system in the future, if radon was found to be high.

Schmidt argues, however, that simply making it easier to address radon gas exposure in the future isn’t good enough. He thinks building codes should follow BC’s example and require all new homes to have a system that draws radon gas from below the home to the outside.  Without a venting system, new homes can have even higher levels of radon compared to old homes, because they are sealed tightly, says Schmidt, based on results from the hundreds of homes tested for free by the Memorial Society.

Schmidt argues governments’ slow movement on building codes and provincial legislation to reduce radon gas exposure is reminiscent of the time it took to mandate seat belts.

“More people die from radon gas than from car accidents,” Schmidt says. “It wasn’t until seat belts were required by law that companies started putting them in cars.”