Radon is an invisible, tasteless and odorless insidious Class A carcinogen (cancer-causing). Radon, a radioactive gas, is formed from the natural breakdown or decay of uranium in rocks and soils. It's found in nearly all soils across the world. It typically moves up through the ground and seeps into your home through any access point in your home. Common entry points are cracks, fissures and other openings in the foundation, drainage or sump openings or poorly sealed pipes. Your home traps radon inside, where it can accumulate. Any home can have a radon problem, not just those built on soil and rock with high geologic potential for radon release.

Radon Decay Chain


Breathing air with elevated radon levels over prolonged periods of time can cause lung cancer. In fact, the Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today and is the leading cause of lung cancer in nonsmokers. If you smoke and your home has high radon levels, your risk of lung cancer is especially high. Radon is estimated to cause about 21,000 lung cancer deaths per year, according to EPA's 2003 Assessment of Risks from Radon in Homes.

The Environmental Protection Agency of the US Government has set an action threshold level of 4.0 pCi/L (picocuries per liter of air) as a safe indoor level. The World Health Organization has set 2.7 pCi/L as a safe indoor level.

The average concentrations in the United States are 1.3pCi/L indoors and 0.4pCi/L outdoors.



How is Radon Measured?

Radioactivity is measured in Curies (Ci) or in metric measurement units which are becquerel (Bq).

What is a picocurie? A picocurie is a unit of measurement of radioactivity, equal to the amount of a radioactive isotope that decays at the rate of 3.7 × 1010 disintegrations per second. It was named after Marie Curie, a Polish born chemist who shared the Nobel Prize in 1903 with her husband Pierre Curie and Henri Becquerel for their collaborative research on radioactivity. In addition, Madame Curie won a second Nobel Prize in 1911 for her discovery and study of radium and polonium now found in the periodic table of chemical elements. 

A Becquerel, is a unit of radiation equal to one disintegration per second also known as the SI unit. SI stands for International System of physical elements.  Becquerel’s or Bq/m3 is a globally accepted unit of radioactive measurement. Picocuries/liter is used almost exclusively in the United State of America.

1pCi/L = to 37 Bq/m3

Most people think radon gas is the danger however the primary risk of lung cancer to radon comes from exposure to radon's decay products. When radon gas is inhaled, it will most likely be exhaled again before it starts to decay. The reasoning behind this is because radon gas is inert which means it is has no real chemical reactivity. However, radon gas has a half-life of 3.8 days and will start to decay into radioactive alpha particles. It is these alpha particles that emit ionizing radiation, which is the danger to lung tissue. These decay products can be breathed in without any attachment and deposit themselves in the lungs. A more likely situation occurs when the alpha particles attach themselves to particles of dust, lint, dander, aerosols and smoke that are floating in the air. The attached or unattached particles will adhere to the lung tissue and due to the short half-life of the decay products, alpha particles that remain decays while in contact with lung tissue. The alpha particles will release energy, which can cause permanent damage to DNA molecules. Damaged DNA will replicate and may cause lung cancer.


How Radon Gas Affects Humans