Radon Information

Radon is a naturally occurring colorless, odorless, tasteless radioactive gas that is formed from the normal radioactive decay of the element radium. Radioactive decay is a natural, spontaneous process in which an atom of one element decays or breaks down to form another element by losing atomic particles namely the protons, neutrons and the electrons. When solid radium element decays to form radon gas, it loses two protons and two neutrons. These two protons and two neutrons are called an alpha particle, which is a type of radiation. The elements that produce radiation are called radioactive. Radon itself is radioactive because it also decays, losing an alpha particle and forming the element polonium.

Elements that are naturally radioactive include uranium, thorium, carbon and potassium. Uranium is the first element in a long series of decay that produces radium and radon. It is present in small amounts in most rocks and soil. It slowly breaks down to other products such as radium, which breaks down to radon. Some of the radon moves to the soil surface and enters the air, while some remains below the soil surface and enters the groundwater (water that flows and collects underground). Uranium has been around since the earth was formed and has a very long half-life (4.5 billion years), which is the amount of time required for one-half of uranium to break down.

The decay of each radioactive element occurs at a very specific rate. How fast an element decays is measured in terms of the element “half-life”, or the amount of time for one half of a given amount of the element to decay. Uranium has a half-life of 4.4 billion years, so a 4.4-billion-year-old rock has only half of the uranium with which it started. The half-life of radon is only 3.8 days. If a jar is filled with radon, in 3.8 days only half on the radon would be left. But the newly made daughter products of radon would be in the jar including polonium, bismuth and lead. Polonium is also radioactive – it is this element, which is produced by radon in the air and in people’s lungs that can hurt lung tissue and cause lung cancer.

Why do radon levels vary so much between indoor air, outdoor air, outdoor air, soil air, and ground water? Why do some houses have high levels of indoor radon while nearby houses do not? The reasons lie primarily in the geology of radon – the factors that govern the occurrence of uranium, the formation of radon, and the movement of radon, soil gas and ground water.

Adapted from: U.S. Environmental Protection Agency

1992, A Citizen’s guide to Radon: The Guide to Protecting Yourself and Your Family from Radon (2^nd Edition)

1993, Home Buyer’s and Seller’s Guide to Radon

1992, Consumer’s Guide to Radon Reduction: How to Reduce Radon Levels in Your Home

1992, National Residential Radon Survey: Summary Report

• Radon-Characteristics • Radon-Definition • Radon-Human-Health • Radon-Exposure • Radon-Smoking •