By Stephen R. Tischler

On January 13, 2005 United States Surgeon General Richard Carmona issued a Health Advisory warning Americans about the health risk from exposure to radon in indoor air. Carmona highly recommended that all Americans test the indoor air in their homes to find out how much radon they might be breathing. The EPA and other organizations declared January 2005 as National Radon Action Month.

Why is the EPA so concerned with radon contamination of indoor air? Simply stated, long term exposure to elevated levels of radon increases the risk of contracting lung cancer. In fact, radon in the air is considered the second leading cause of lung cancer. It is estimated that over 20,000 Americans die from radon-related lung cancer each year.

Radon is an odorless, colorless, tasteless gas that occurs naturally in almost all soils. The natural radioactive decay of uranium in the soil produces the carcinogen, which can be found all over the world. The EPA created a map of radon zones in the United States, and it indicates the potential for radon at various levels in every state.

Radon gets into buildings (houses, offices, factories, school, hospitals, etc.) primarily through cracks and openings in the foundations. It can also be carried into a building through the water supply. Once inside, radon can be trapped and unless properly ventilated to remove it, the accumulation can quickly become a serious health hazard. Even though the EPA created a zone map indicating the potential for radon levels in the U.S., these levels vary greatly from state to state, county to county and even home to home. Because radon is odorless, colorless and tasteless, testing is the only way to know if you are at risk from radon contamination of the indoor air in the buildings you occupy. There are two kinds of radon tests commercially available, “radon in air” and “radon in water”.

Testing radon in air
Testing for radon in air is easy and takes very little time to set up. The amount of radon in the air is measured in picocuries per liter of air (pCi/L). Because the level in the air can vary from day to day, a long-term test lasting more than 90 days is the best way to determine the average radon level present in the building year-round. Short-term tests lasting two to 90 days are also available, but can be less effective. The most common testing methods include charcoal canister, alpha track, electret ion chamber, continuous monitors and charcoal liquid scintillation.

Testing radon in water
As mentioned previously, radon can enter a building through the water supply. Typically, the gas can accumulate in water from underground sources, like wells. It is not, generally, a concern when the source water comes from a lake or river, because the radon is released into the air before it gets to the building. It is estimated that less that one percent of the radon in air comes from the building’s water source, but it does contribute to the overall level of radon detected in indoor air. Not all the radon is released from the water that enters the building, and drinking this water does present a cancer risk. The risk, though, is less than the risk from radon in air.

You should be concerned about radon in drinking water primarily if your water comes from a groundwater source and dealers serving groundwater customers should provide information about radon in their regular sales pitch. Test kits to measure radon in water are available, and should be conducted by approved water analysis laboratories. State health departments can provide the names of certified laboratories that test for radon in water.

Remediation of airborne radon
The average indoor radon level is estimated to be about 1.3 pCi/L. The outside air normally contains about 0.4 pCi/L. Radon from water is a small contributor to the total radon in indoor air. Water that contains 10,000 pCi/L will only contribute only about 1 pCi/L to the air, though activities such as showering or washing clothes will typically transfer greater amounts of radon to the air. While no level of radon in the air is risk free, remediation is generally recommended above 4.0 pCi/L. There are several proven methods to reduce radon in a building. The most widely used method is to install a vent pipe and fan to pull the radon out of the soil beneath your building and exhaust it to the outside air. Sealing foundation cracks and other openings is also recommended.

Remediation of waterborne radon
If radon is found in your source water and you are concerned enough to seek remediation, there are three primary methods.

  1. Increase the ventilation in bathrooms, laundry rooms and kitchens to prevent a buildup of radon that is released from the source water.
  2. Install a Granular Activated Carbon (GAC) filtering system. These systems are very effective at reducing radon in water. However, radioactivity buildup on the filter media may create disposal issues. GAC systems should only be installed outside the building.
  3. Install an aeration system that mixes air with the source water in a chamber vented to the outside. Like GAC systems, aeration has been shown to be very effective and they have an advantage, because radioactivity does not accumulate.

The message here is clear. Buildings should be, at the very least, tested for indoor air radon contamination. This is particularly true for homeowners. Additionally, if water comes from a groundwater source, like a private well, it should also be tested. To increase awareness of this issue, POU/POE dealers should also be encouraging radon testing of both the air and water. Dealers and consumers would benefit from the addition of this diagnostic testing prior to recommending water treatment solution options.


  • A Citizen’s Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon, U.S. Environmental Protection Agency.
  • Radon in Drinking Water: Questions and Answers, U.S. Environmental Protection Agency
  • Map of Radon Zones, U.S. Environmental Protection Agency,
  • Nationwide Occurrence of Radon and Other Natural Radioactivity in Public Water Supplies. 1985. USEPA 520/5-85-008. U.S. Environmental Protection Agency, Washington, D.C. Radon Reduction Techniques for Detached Houses: Technical Guidance. 1988. USEPA/625/5-87/019. U.S. Environmental Protection Agency, Washing ton, D.C.

About the author
Stephen R. Tischler is director of sales and marketing for National Testing Laboratories and a member of the 2005 WC&P Technical Review Committee. A former analytical chemist at NASA, He has a long history in the aerospace industry with expertise in quality control and analytical testing method development. Tischler has a bachelor’s degree in chemistry from John Carroll University and a master’s degree in business from Baldwin-Wallace College. During National Radon Action Month and throughout the remainder of the year, National Testing Labs will be encouraging consumers to test their air and water (if they are on a private well), and assisting in helping POU/POE dealers to do so as well. For more information, call (440) 449-2525, or visit


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