The Building Inspector of Connecticut

Radon Testing

Radon Gas*

(*Info sources: MA Depart. Public Health, American Lung Association, U.S. EPA & Niton Corp.)


Radon is a naturally occurring radioactive gas. It is produced in the ground through the normal decay of uranium and radium. Dig up the top 6 feet of an acre of land and you will find, on average, about 50 pounds of uranium. Uranium decays to radium, which then decays to radon.

Radon itself is an inert gas & poses no danger, but radon decays to polonium & lead particles. These and later progeny are chemically very active as well as radioactive. When you breathe, these radioactive progeny lodge in your lungs, bronchi, and trachea. The radiation disrupts and mutates cells and can, eventually, result in lung cancer. Radon is estimated to be the second leading cause of lung cancer in the United States. It is a potential problem in every state. Its health risk increases with the length of exposure and concentration level of the radon.

Radon moves through small spaces in the soil and rock on which a house is built and can seep into a home through dirt floors, floor drains, sump pits, cracks in the foundation and basement floor & up through hollow core block foundation walls. Differences in air pressure between the basement and the soil beneath the home also play a part in the migration of radon gas.

The EPA has set the level of concern at 4 picoCuries of radon per liter of air (4 pCi/L). This is a concentration of 70,000 atoms of radon in each liter of air (about 2 million radon atoms in every cubic foot of air). This is a very low concentration, roughly one radon atom in a billion-billion air atoms, however, the radon atoms are radioactive and that makes the difference. We breathe about 20 liters of air into our lungs each minute. At 4 pCi/L we accumulate about 10,000 radioactive atoms in our lungs, trachea, and bronchi every minute.

If 1,000 people who never smoked were exposed to 4 pCi/L over a lifetime,

about 2 people could get lung cancer.

If 1,000 people who smoked were exposed to 4 pCi/L over a lifetime,

about 29 could get lung cancer.

If 1,000 people who never smoked were exposed to 20 pCi/L over a lifetime,

about 8 people could get lung cancer.

If 1,000 people who smoked were exposed to 20 pCi/L over a lifetime,

about 135 could get lung cancer.

The Building Inspector of Connecticut uses continuous radon monitors (CRM’s) to measure radon gas. These instruments provide more information than charcoal canisters or other similar devices. A graphic printout of the results shows the hourly radon readings for the test period. The CRM is placed in the house for a minimum of 48 hours. For an accurate radon test, “closed house” conditions must be maintained for 12 hours prior to testing and throughout the test period. This means that doors and windows must be kept closed, except for normal traffic in and out of the house, and systems which draw in outside air (whole-house fans, air conditioners set on “fresh air”, etc.) should not be used.

There are several remedies for reducing radon concentrations in the home. The most widely used method is the “sub-slab depressurization” system. This involves the installation of pipes and fans. This system prevents radon gas from entering the home from below the concrete floor and the foundation. Radon reduction contractors may also use other methods depending upon the design of the home. In addition to the installation costs, there are also operating costs. Ways to reduce radon are discussed in the EPA’s Consumer Guide to Radon Reduction, call you state radon office to obtain a copy. Installation costs to lower radon levels can range from $500 to about $1000. Be sure the contractor is listed with the EPA’s Radon Contractor Proficiency Program.

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