What is Radon?
Radon is a radioactive gas found naturally in the environment. It is produced by the decay of uranium found in soil, rock or water. Radon is invisible, odourless and tasteless and emits ionizing radiation. As a gas, radon can move freely through the soil enabling it to escape to the atmosphere or seep into buildings. When radon escapes from the bedrock into the outdoor air, it is diluted to such low concentrations that it poses a negligible threat to health. However, if a building is built over bedrock or soil that contains uranium, radon gas can be released into the building through cracks in foundation walls and floors, or gaps around pipes and cables.
When radon is confined to enclosed or poorly ventilated spaces, it can accumulate to high levels. Radon levels are generally highest in basements and crawl spaces because these areas are nearest to the source and are usually poorly ventilated. In the open air, the amount of radon gas is very small and does not pose a health risk.
The only known health effect of radon is an increased chance of developing lung cancer. Radon is the second leading cause of lung cancer after smoking. Because it is radioactive, radon decays. As it decays, radon produces decay products, sometimes called "radon daughters" or "radon progeny". Radon gas and radon progeny in the air can be breathed into the lungs where they breakdown further and emit "alpha particles". Alpha particles release small bursts of energy which are absorbed by nearby lung tissue. This results in lung cell death or damage. When lung cells are damaged, they have the potential to result in cancer when they reproduce.
Not everyone exposed to radon will develop cancer. The time between exposure and the onset of the disease is usually many years. Unlike smoking, occasional exposure to radon does not produce any symptoms, such as coughing or headaches.
Your risk of developing lung cancer from radon depends on the concentration of radon in the air you breathe and the length of time you are exposed. If you are a smoker also exposed to elevated levels of radon your risk of lung cancer is significantly increased.
Health Canada Report on Concentrations in Homes
From the data collected, it can be seen that there are several regions of the country where indoor radon is more prevalent. The current estimate of the percentage of Canadians living in homes above the 200 Bq/m3 guidelines, based on the completed two-year dataset, is 6.9%. This percentage is slightly higher than the previous estimate of 5% of Canadians, however, the current estimate factors geographic locations and is based on long-term (three-month) radon testing. New Brunswick, Manitoba, Saskatchewan, and Yukon Territory are the provinces/territories which showed the highest percentages of homes testing above the guideline in this study. There were 14 Health Regions where the raw percentage of homes testing above the guideline ranged from 23 to 44%. Five of these were in Manitoba, four in New Brunswick, three in Saskatchewan, and one each in Quebec and British Columbia. There were another nine Health Regions where the raw percentage of homes above the radon guideline ranged from 16 to 21%. Fifty-four (45%) of the Health Regions had 10% or more of their homes above the guideline level. The data obtained from this survey will enable Health Canada to more effectively target testing and awareness programs; however, it must be re-iterated that all Canadians are encouraged to test their homes to determine their indoor radon levels.