Dealing With Radon in an Old House

Roger Diez

Part 1 of 8 in The Old House Web Home Hazards Series

You have heard about radon and its dangers, but you may not know exactly what it is, what it does, and where it comes from. Radon is an invisible, odorless gas that is produced by the decay of radioactive materials (Uranium and Thorium) that occur naturally in soil, rock, and most elements of the earth's crust. Radon is the heaviest known gas, nine times heavier than air. It is also the second leading cause of lung cancer.

How Does Radon Enter Homes?

Because of the abundance of radioactive materials in the earth's crust, radon can enter your home in many ways; it can come in through the soil under the home, from building materials (concrete, stone) used in construction, or in water saturated with this water-soluble gas flowing near the home. Radon concentrations tend to build up over time, starting in the lowest levels of the house (basement and crawl spaces) and migrating upward into other areas of the home via air circulation. Since the gas is invisible and odorless, special testing equipment is required to detect it.

How is Radon Detected?

There are two methods of radon detection, passive and active. Passive test devices collect samples over time, and then are analyzed in a laboratory. Active devices constantly monitor the radon levels in their vicinity and display the results in real time. You can obtain a passive device kit designed for homeowner use, or you can engage a professional to test your home.

What if Your House Has High Radon Levels?

If testing reveals high levels of radon, you may be advised to take action. High concentrations of radon can be dangerous. Increasing ventilation to the areas affected may be enough to disperse the radon and reduce it to safe levels. But preventing radon from entering the lower levels of the house is the preferred long-term solution. Sealing porous construction materials such as concrete blocks in basement walls, and blocking other entry points like openings for pipes and cables may take care of the problem. Use a certified professional to ensure that the job is done correctly.

Radon, like many problems found in older homes, is only dangerous if you don't know about it and don't act on that knowledge. For your own peace of mind, test for high radon levels, and take action if indicated by the test results.

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