The Invisible Killer in Your Home: Understanding Radon, Testing, and Mitigation


Radon is an invisible, odorless, and tasteless radioactive gas that is released into the air or dissolves into groundwater as uranium in rocks or soil decays. It was classified as a human carcinogen in 1988 by the International Agency for Research on Cancer, but the ill health effects of this invisible killer had been observed for centuries in Europe.

Radon is an invisible, odorless, and tasteless radioactive gas that is released into the air or dissolves into groundwater as uranium in rocks or soil decays. It was classified as a human carcinogen in 1988 by the International Agency for Research on Cancer, but the ill health effects of this invisible killer had been observed for centuries in Europe.

To increase the public’s awareness of radon’s health risks, promote radon testing and mitigation, and advance the use of radon-resistant new construction practices, the US Environmental Protection Agency (EPA) has designated January as National Radon Action Month. The EPA estimates that one in every 15 homes nationwide has a radon level at or above the recommended action level of 4 picocuries per liter (pCi/L) of air, which according to New York Times articles from 2008 is a level that has “about the same risk for cancer as smoking a half a pack of cigarettes per day” and delivers the same amount of radiation per year as receiving more than 200 chest radiographs. Unless you are buying or selling a home, when radon testing may be mandatory, you may not know if the radon levels in your home are in the danger zone. Many kits are readily available to help you to determine your home’s radon levels, and if they are found to be elevated, there are various mitigation strategies that can be explored, some for nominal cost. We explore radon, testing, how to locate a radon mitigation professional, and describe some of the online resources that can help you safeguard your home from this silent carcinogen.

Radon throughout the ages

In 1530, Phillip von Hohenheim, a Swiss physician also known as Paracelsus, noted a malady of the lungs that killed metal miners in Saxony and Bohemia. He referred to this disease as “mala metallorum” in his book Von der Bergsucht oder Bergkranckheiten drey Bücher (1533-1534), which was the first book to focus specifically on an occupational disease. In 1556, Georg Agricola, a German scientist and mineralogist, recommended ventilation of mine shafts and use of veils by miners to avoid this debilitating illness in his book De Re Metallica. Although this condition was identified as lung cancer by Herting and Hesse in 1879 upon studying miners from Schneeberg, Germany, radon itself wasn’t discovered until 1900 by Friedrich Ernst Dorn, and a connection between radon and cancer was only established during the early part of the Cold War (1945-1991), when it was noted that uranium miners succumbed to lung cancer at high rates. The link between lung cancer and radon exposure was eventually confirmed in animal studies.

In 1984, it was discovered that uranium miners weren’t the only individuals at risk, when a nuclear engineer named Stanley Watras set off radiation monitors at the Limerick Nuclear Power Plant in Pottstown, Pennsylvania, where he was employed. After no leaks were discovered at the plant, safety officials visited his home and found radiation levels at more than 100,000 times the normal level, with 4400 pCi/L of radon in this basement, 3200 pCi/L in his living room, and 1800 pCi/L in his bedrooms. A natural radon vent was discovered below his house, which was pumping massive amounts of radon into his home.

What we know today

Today, radon is known to be the second leading cause of lung cancer and the leading cause of lung cancer in nonsmokers in the United States. The risk of lung cancer is greatest in smokers exposed to radon, with the majority of the approximately 15,000 to 22,000 lung cancer deaths occurring in these individuals annually.

Numerous studies have examined whether a link may also exist between leukemia and indoor radon exposure, especially in pediatric patients, but most have failed to establish such a correlation; however, a recently published epidemiological study of childhood leukemia in Denmark that included 2400 patients and 6697 controls between 1968 and 1994 found a weak but statistically significant correlation between residential radon exposure and acute childhood lymphoblastic leukemia. Studies examining possible links between radon exposure and stomach cancer, cardiovascular diseases, multiple sclerosis, and a host of other maladies have also been undertaken, yielding mixed results.

Do you live in a radon hot zone?

You can find out if you live in a zone with potentially high radon concentrations by visiting the EPA Website, where you can access a map outlining radon zones throughout the United States and can also search for radon maps by state. Thus far, the highest average radon concentrations have been observed in Iowa and southeastern Pennsylvania, but according to a report published by the World Health Organization (WHO) in 2009, “the majority of radon-induced lung cancers are caused by low and moderate radon concentrations rather than by high radon concentrations, because in general less people are exposed to high indoor radon concentrations.” If you discover that you live in an area with potentially high concentrations of radon, it is especially important to test your home for radon, but even if you live in an area predicted to have low levels (< 2 pCi/L), you cannot guarantee that the levels in your home are in that range unless you test.

Obtaining radon test kits

Although you can have your home professionally tested for radon, using a do-it-yourself kit is easy and economical. Radon test kits can be found at many home improvement stores, through online sources such as the Kansas State University National Radon Program Services, and sometimes for free from local or county health departments or state radon programs. Throughout the month of January, more states are providing free tests to their residents to acknowledge National Radon Action Month, including Missouri, Vermont, Colorado, and Pennsylvania, so it is worthwhile to contact your state’s health department or conduct an online search to see if your state is offering them.

What test should I buy?

Several types of radon test kits are on the market, including short-term and long-term tests, radon water tests, and electronic radon detectors. With so many choices, it may be difficult to determine what you need. Short-term tests, which remain in your home from 2 to 90 days, are the most commonly used. These tests cost approximately $15 each, which includes laboratory analysis. The EPA recommends using two or more of these kits throughout the year to ensure accuracy of the readings because the absorptive material of these tests can react to temperature and humidity changes, especially during transit, which may affect their precision. Radon levels also vary daily, so using multiple tests throughout the year gives a more accurate assessment of your year-round mean radon level. If you would rather avoid the hassle of dealing with multiple short-term tests, you may opt to use a long-term radon test instead. Long-term tests cost between $25 and $45 and remain in your home for more than 90 days, with some remaining in your home for up to a year.

While the risk of lung cancer from inhaling radon is far greater than the risk of gastric or other cancers from ingesting water containing radon, radon can be released into the air when using water for daily living activities such as showering, contributing to lung cancer risk. The risk of radon entering your home through water is generally low, unless your water is from a ground water source, such as a private well, or a public supply that uses ground water. If your water comes from a public supply, you should receive a Water Quality Consumer Confidence Report (CCR) every year from your city or township, which will include radon levels. To learn more about these reports and how to decipher them, you can visit NSF International. If you have a private well or want to confirm the radon results of your CCR, you can buy a radon water test kit. These tests generally cost between $25 and $40, which includes laboratory assessment. If you have any questions about radon in drinking water, you can contact the Safe Drinking Water Hotline at (800) 426-4791.

A few years ago, the risk of radon leaking from granite countertops made mainstream news. Although most experts agree that the risk of radon being emitted from most granite countertops is extremely low, slabs emitting more than 4 pCi/L have been identified. In an interview with CBS in 2008, Stanley Liebert, quality assurance director at CMT Laboratories in Clifton, New York, noted that certain colors seem to pose a higher risk than others, with reds, pinks, and purples appearing to emit the highest levels. Other reports have indicated that the exotic and striated granite varieties from Brazil and Namibia are the most suspect. Because uranium levels in granite are not measured or controlled, the only way to guarantee your granite countertop is not a radon hot zone is by testing it. A pack of seven tests can be purchased for $79.95 at, where you can also watch a video on how to use these tests.

If you wish to continuously monitor your home for radon, as you may already be doing for carbon monoxide, you can opt to purchase an electronic radon detector instead. Currently, the Safety Siren Pro Series3 HS71512 Electronic Radon Gas Detector is the only radon gas detector designed specifically for use by homeowners. It is available through for approximately $125. The Safety Siren Pro features a numeric LED display to show the level of radon gas in the air, and offers both a short-term reading that displays the average radon level over the past 7 days and a long-term reading that displays the average radon level since being powered-up or since the last reset within the past 5 years. If the long-term measurement reaches 4 pCi/L or greater, or if the short-term measure stays above 4 pCi/L for 30 consecutive days, an alarm will sound.

Radon mitigation

If radon testing reveals a level of 4 pCi/L or more, it is important to fix your home to mitigate risk, but even levels between 2 pCi/L and 4 pCi/L pose some risk and may warrant a repair. Costs of radon mitigation generally average between $800 and $2500. A comprehensive overview of mitigation techniques is available at the EPA Website. If you are handy, you may be able to handle some of these repairs yourself, but because mitigation generally requires sealing basement foundations, concrete slab floors, or areas under crawl spaces, and installing ventilation or radon collection systems, these tasks may be best left to the professionals.

To find a radon service professional in your area, you can visit and then select your state, which will pull up contact information for state radon programs and other organizations that can help you identify contractors in your area. You can also opt to contact one of the following privately-run National Radon Proficiency Programs, which provide accreditation and certification in radon testing and mitigation. Both organizations maintain a database of certified radon professionals on their Website:

The National Environmental Health Association (NEHA)

National Radon Proficiency Program

Phone: (800) 269-4174 or (828) 890-4117

Fax: (828) 890-4161

The National Radon Safety Board (NRSB)

Phone: (866) 329-3474

Fax: (914) 345-1169

If you prefer to tackle the radon problem yourself, you may consider purchasing Protecting Your Home from Radon: A Step by Step Manual for Radon Reduction by Douglas L. Kladder and colleagues before you get started. The book has a 5-star rating on Amazon based on two reviews. One reviewer commented, “[The book allows] a reasonably competent DIYer to design and install their own radon mitigation system. In addition, it covers the necessary safety precautions to take in the process.” The book is not available directly through Amazon, but can be purchased through Air-Chek for $29.95, including shipping and handling, by calling (800) AIR-CHEK.

Take-home message

January is a time for making resolutions to improve health, and while resolving to eat better and exercise are important, environmental health risks should not be overlooked. Radon gas exposure is a known risk factor for lung cancer, and more studies are showing that it may contribute to the development of other health issues as well, such as leukemia. Radon testing is inexpensive and easily performed, and mitigation costs are no greater than most other home improvements. As you know from treating patients with cancer, health is our most precious commodity, so don’t let radon rob you, your loved ones, or your patients and their families of it. Click here to view a video of a patient discussing his experience with radon-related lung cancer, and take action by testing your home and encouraging your patients to do the same.

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