Radon is a naturally occurring element (Rn) produced by the radioactive decay of radium. Because of its radioactivity, it is considered a health hazard.
The US Environmental Protection Agency (EPA) classes radon as a carcinogen. It is the leading cause of cancer in non-smokers and the second leading cause in smokers.
In this article, we will look at what radon is, where it comes from, the health implications of radon exposure and how to minimize risks.
Contents of this article:
Fast facts on radon
Here are some key points about radon. More detail and supporting information is in the main article.
- Radon is a naturally occurring radioactive element
- It is a colorless, odorless and tasteless gas
- Radon is found in the atmosphere, but it has a tendency to accumulate in buildings
- Some of the highest recorded levels of radon were found in a town in County Cork, Ireland
- Radon can increase the risk of lung cancer, especially when combined with smoking
- There are a number of ways to reduce radon build-up in the home
- Before appropriate ventilation became mandatory, many miners developed lung cancer from radon exposure
- Simply making your home airtight is not enough to prevent radon from building up
- Radon is heavier and denser than air so often accumulates in basements.
What is radon?
Radon is created by the decay of radium.
Radium decays to produce radon which then emanates from uranium ores, shales, phosphate rock, igneous and metamorphic rocks such as granite, and, to a lesser degree, more common rocks such as limestone.
Radon is a gas at standard temperatures and pressures, in fact, it is one of the most dense substances that remains a gas under normal circumstances.
As a colorless, odorless, tasteless gas, radon is undetectable by human senses alone.
Radon is all around us, but in very small quantities. However, it can pool in buildings. Radon accounts for the majority of most people's exposure to ionizing radiation.
Where is radon found?
Radon tends to enter buildings at their lowest point. It often makes its way in through splits in foundations, cracks in walls, gaps around pipes, cavities inside walls and the water supply. The gas is likely to accumulate in airtight buildings that are insufficiently ventilated.
Levels vary substantially from location to location and, although the half-life of radon is less than 4 days, it can build up in high concentrations, especially in low areas such as basements or mine shafts.
The highest levels of radon in the US are to be found in Iowa and the Appalachian Mountain areas in southeastern Pennsylvania.1 However, it is worth noting that two adjacent homes - indeed, two adjacent rooms - can vary significantly in their levels of radon.
The high levels of radon in Iowa are due to ancient glaciers which ground down granite rocks and deposited them as the rich soil that covers Iowa today.
Some of the highest radon readings ever found were taken in the town of Mallow in County Cork, Ireland.2
Radon has also been found in some spring water and hot springs.3
On the next page, we look at the health effects of radon and how to remove it from your home.