Radon is a naturally occurring radioactive gas that is produced by the breakdown of uranium in soil, rock, and water. It is invisible, tasteless, and odorless, which makes it difficult to detect without special equipment. Radon typically enters buildings through cracks in foundations, gaps around pipes, and other openings in floors or walls in contact with the ground. Since radon can accumulate in enclosed spaces, particularly in poorly ventilated areas like basements, it poses significant health risks when present at high levels.

In Canada, radon is a serious environmental and public health concern. According to Health Canada, radon exposure is the second leading cause of lung cancer in the country, after smoking. Approximately 16% of all lung cancer deaths in Canada are attributed to radon exposure. This underscores the importance of radon testing and mitigation to ensure the safety of homes and workplaces.

Radon is part of the uranium-238 decay chain. As uranium in the ground naturally breaks down over time, it forms radium, which eventually decays into radon gas. This gas can move through the soil and into the air, where it is diluted to harmless levels outdoors. However, when radon becomes trapped inside homes and buildings, it can accumulate to levels that increase the risk of lung cancer.

Radon levels tend to be higher in certain regions depending on the local geology. In Canada, some of the highest radon levels are found in areas like the Prairies, parts of Ontario, British Columbia, and Atlantic Canada. However, no region is completely safe from radon, and even homes in low-risk areas can have elevated levels.

While radon gas itself is inert and doesn’t chemically react with other substances, its radioactive decay products, known as radon progeny, are harmful. When radon gas decays, it releases tiny radioactive particles that can attach to dust and other particles in the air. These radioactive particles are easily inhaled and can become lodged in the lungs.

Once in the lungs, radon progeny continues to decay, emitting alpha particles that can damage lung tissue at the cellular level. This damage can lead to mutations in the DNA of lung cells, increasing the risk of developing lung cancer. According to Health Canada, radon exposure accounts for about 16% of lung cancer deaths annually.

For smokers, the risk is even higher. The combination of smoking and radon exposure is particularly dangerous. Health Canada reports that the risk of lung cancer for smokers exposed to high levels of radon is significantly higher than for non-smokers. This synergistic effect makes radon mitigation particularly critical in homes where smoking occurs.

The risk posed by radon is influenced by several factors, including:

1. Radon concentration levels – Higher concentrations of radon in a building increase the risk of lung cancer.
2. Duration of exposure – Long-term exposure to radon, even at moderately high levels, can substantially increase lung cancer risk.
3. Smoking status – Smokers exposed to radon are at much greater risk compared to non-smokers exposed to the same levels of radon.

Radon levels are measured in becquerels per cubic meter (Bq/m³). The Canadian guideline for radon in indoor air is 200 Bq/m³. Health Canada recommends taking action to reduce radon levels if concentrations exceed this limit. However, it is important to note that radon concentrations below 200 Bq/m³ still pose a risk, and no level of radon exposure is entirely without risk.

Given the significant health risks associated with radon exposure, testing for radon and mitigating high levels is essential. Radon is a widespread issue in Canada, and homes in all provinces and territories are at risk, regardless of their age or construction type. Radon levels can vary dramatically between neighboring homes, so testing is the only way to know whether radon is present at dangerous levels.

Reducing radon exposure is particularly important for individuals who smoke, as the combination of smoking and radon exposure greatly increases the risk of lung cancer. However, non-smokers are also at risk, and all Canadians should consider testing their homes for radon, especially if they live in areas known for high radon levels.