Radon – Still a Risk?

Although January was National Radon Action Month, radon seems to have slipped from the housing headlines, having been supplanted first by mold, then lead paint and more recently by foreclosures.  Radon, however, continues to be a problem and should not be ignored.  Why? Radon is dangerous and exposure to it has been linked to lung cancer in humans.

According to the Environmental Protection Agency (EPA), radon is a “gaseous radioactive element …it is an extremely toxic, colorless gas … derived from the radioactive decay of radium”.  Radon moves up through the ground.  It enters your home through cracks and gaps in your foundation where it is trapped.  Over time radon concentrates in the air we breathe in our homes.  Since we spend a lot of time in our homes, breathing air with dangerous levels of radon can cause cancer.

The EPA has mapped the relative radon levels in the U.S.A., by county.  It should be noted that even if your home is located in an area of low radon risk, you should still have your home tested.  Home risk levels can vary widely within individual counties.

There are several methods for testing radon levels in your home.  Many home inspectors utilize testing equipment as a part of a pre-sale home inspection.  The testing device is placed in the lowest level of the home for a 24 hour period.  Radon levels are measured continuously during that time and results are available immediately.

Home test kits are inexpensive and readily available at home centers for do-it-yourself testing.  The test kits are deployed per the instructions for a specified period, typically 2 to 7 days.  After the testing is complete the kits are mailed to a lab for analysis.  Typically the results are returned by mail within a week or two.

Before actually conducting the test you should complete the following preparations:

  • Doors and windows should be closed for a period of 12 hours before beginning the test
  • Minimize activity in the area where the test will be conducted, typically the basement
  • Sump lids should be sealed – both around their perimeter and around the piping
  • Any large open cracks or joints in the floor slab should be sealed
  • Pipe penetrations of the floor slab should be sealed
  • A gallon of water should be poured into each floor drain

When Robert R. Jones Homes conducts radon testing for models or specs we always use 2 kits located between 10 and 20 feet apart.

You’ve received your test results, but what do they mean?  According to the EPA, outdoor radon levels average between 0.4 pCi/L (Picocuries per Liter which is the measurement of radioactivity) and 0.75 pCi/L.  Indoor radon levels are limited to 4.0 pCi/L by the EPA.

If you followed the preparation steps above and your test results are below 4.0 pCi/L, you are done.  If your results show radon levels above 4.0 pCi/L, or you would like to lower your radon levels further, you should contact a radon mitigation company.

Mitigation usually involves installing PVC piping, through the roof, to vent the basement slab.  This passive radon venting method, which in many new homes involves adding piping from the sump basket, is designed to provide an easy escape path for radon gas before in enters your home.

Depending upon the initial radon levels measured, the mitigation contractor may install a continuous fan in the piping to draw the radon gas from below the slab.  When the mitigation has been completed, another test is conducted to demonstrate that mitigation has been effective.


WHO Handbook on Indoor Radon – A Public Health Perspective

EPA – Radon Health Risks


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