General Radon Information

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RADON -Symbol (RN)
Radon is a colorless, odorless, tasteless gas created by the natural decay of radium.   Radium is part of the decay chain that produces radon gas. The "Grandfather" of this decay chain is uranium 238.   Radon, radium, and uranium are all naturally occuring elements and can be found on the Periodic Table of Elements.  

The decay chain sequence for radon 222 is as follows: Radon 222Polonium 218 > Lead 214Bismuth 214 > Polonium 214 > Lead 210 (stable).

Radon is an inert gas, which means it's chemically inactive. Since it is chemically inactive, radon can move easily through all gas permeable materials. This is why basements with no visible signs of cracks or penetrations still have radon problems. It's because the gas can permeate directly through the concrete slab.

The most common way radon concentrations are expressed is in "picoCuries per liter" (pCi/L). A pCi/L is one-trillionth of a curie. A "curie" (named after famed radiation scientist Madame Curie) is the amount of activity given off by the decay of one gram of Radium, which is the equivalent of 2.2 disintegrations per minute, in a liter volume.

Radon is classified as a "Class A" Carcinogen which means positive links have been made between radon exposure and lung cancer from physical models, animal studies and most importantly; human epidemiological studies. The U.S. Surgeon General has stated that radon exposure is second only to smoking in causing lung cancer in the U.S.

The 4.0 pCi/L action level for airborne radon was established by the EPA because attaining a reduction below that action level is technologically feasible to achieve.  However; EPA's position states that there is no "safe threshold" for exposure to ionizing radiation, therefore; the lower your exposure, the better. See airborne radon risk charts. The EPA also states that you should consider remediating radon levels between 2 and 4 pCi/L. It should be noted that Active Soil Depressurization (ASD)systems installed by Connecticut Basement Systems Radon Inc., often yield post installation airborne radon results below 2.0 pCi/L. See airborne radon mitigation.

There are currently no defined standards for waterborne radon. However, EPA has proposed a maximum contaminant level (MCL) of 300 pCi/L for municipal supplies with an alternative maximum contaminant level (AMCL) of 4,000 pCi/L for municipalities who adopt a multimedia mitigation (MMM) program. Currently, the state of Connecticut suggests that if your waterborne radon concentrations exceed 5,000 pCi/L, you should consider reducing the radon concentrations to below 5,000 pCi/L. Currently, different states have different action levels or guidelines. See waterborne radon mitigation.

Generally speaking, airborne and waterborne radon concentrations are in a constant state of fluctuation. The biggest reason behind air fluctuation is due to the ever-changing weather patterns.

Varying weather conditions create varying pressure differentials, which create varying degrees of influx of radon gas up into the structure from the soil. The foremost condition recognized to create the greatest influx of airborne radon into a structure is known as the "stack effect."

This scenario typically occurs in the heating season when the house is generally closed up the majority of the time. As indoor air is heated to a comfortable temperature, it begins to rise or move vertically through the structure. As the heated air moves vertically through the interior envelope of the structure, the structure itself begins to create suction upon the ground on which it sits. The greater the suction, the greater the influx of radon. It is not uncommon for airborne radon concentrations to fluctuate 100% or more from the cooling season to the heating season.

Waterborne radon levels fluctuate for different reasons, the biggest of which is that as water migrates through fissures and intercises in the sub-surface layers of the earth's crust, it is exposed to a wide array of soil and bedrock compositions. The longer the time frame that a sub-surface volume of water spends in contact with a radium bearing source, the greater the radon concentration that will dissolve into that volume of water. Furthermore, a well that taps into an aquifer that is fed from many different sources will have different degrees of influent water quality feeding in - and mixing together, producing ever-changing contaminant concentrations. For more on water quality, See well water treatment.


RadonChartNote: If you are a former smoker, your risk may be higher.

Based on information contained in the National Academy of Sciences 1998 report, The Health Effects of Exposure to Indoor Radon, your radon risk may be somewhat higher than shown; especially if you have never smoked. It’s never too late to reduce your risk of lung cancer. Don’t wait to test and fix a radon problem. If you are a smoker, stop smoking.

ALL INFORMATION TAKEN FROM THE HOME BUYER’S AND SELLER’S GUIDE TO RADON.