Frequently Asked Questions About Radon

General Questions

Testing Air for Radon

Radon Resistant Construction

Radon Testing During Real Estate Transactions

Mitigating Radon Problems

Radon in Water

 

General Questions

What is radon?

Radon is a radioactive gas. It is colorless, odorless, tasteless, and chemically inert. Unless you test for it, there is no way of telling how much is present.

Radon is formed by the natural radioactive decay of uranium in rock, soil, and water. Naturally existing, low levels of uranium occur widely in Earth's crust. It can be found in all 50 states. Once produced, radon moves through the ground to the air above. Some remains below the surface and dissolves in water that collects and flows under the ground's surface.

Radon has a half-life of about four days—half of a given quantity of it breaks down every four days. When radon undergoes radioactive decay, it emits ionizing radiation in the form of alpha particles. It also produces short-lived decay products, often called progeny or daughters, some of which are also radioactive.

Unlike radon, the progeny are not gases and can easily attach to dust and other particles. Those particles can be transported by air and can also be breathed.

The decay of progeny continues until stable, non-radioactive progeny are formed. At each step in the decay process, radiation is released.

Sometimes, the term radon is used in a broad sense, referring to radon and its radioactive progeny all at once. When testing measures radiation from the progeny, rather than radon itself, the measurements are usually expressed in working level (WL) units. When radiation from radon is measured directly, the amount is usually expressed in picocuries per liter of air (pCi/L).

What health effects are associated with radon exposure?

The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States. There are currently no conclusive data on whether children are at greater risk than adults from radon. No specific subtype of lung cancer is associated with radon exposure.

Only smoking causes more cases of lung cancer. If you smoke and you are exposed to elevated radon levels, your risk of lung cancer is especially high. The U.S. Environmental Protection Agency provides radon risk comparison charts for people who smoke and those who have never smoked. Stop smoking and lower your radon level to reduce your lung cancer risk.

Radon gas decays into radioactive particles that can get trapped in your lungs when you breathe. As they break down further, these particles release small bursts of energy. This can damage lung tissue and lead to lung cancer over the course of your lifetime. Not everyone exposed to elevated levels of radon will develop lung cancer, and the amount of time between exposure and the onset of the disease may be many years.

Breathing radon does not cause any short-term health effects such as shortness of breath, coughing, headaches, or fever.

In 1998, the National Academy of Sciences (NAS) released the Biological Effects of Ionizing Radiation (BEIR VI) Report, "The Health Effects of Exposure to Indoor Radon." The study reviewed and evaluated data from many prior studies and drew conclusions. It fully supports estimates by the EPA that radon causes about 21,000 lung cancer deaths per year. Though some people debate the number of deaths, it is widely agreed that radon exposure is the second leading cause of lung cancer.

Research suggests that swallowing water with high radon levels may pose risks, too, although risks from drinking water containing radon are much lower than those from breathing air containing radon. A NAS report on radon in drinking water, "Risk Assessment of Radon in Drinking Water," was released in 1999. It concluded drinking radon in water causes about 19 stomach cancer deaths per year.

The EPA provides more information about health effects from radon in their publication, Radon—A Physician's Guide.

Should I be tested for lung cancer?

Individuals should bring questions like this to their medical care provider(s). If someone has been exposed to high levels of radon over a long period of time, it is an especially good idea. Such persons may want to speak to their physicians about whether they should get regular health checkups or tests such as low-dose CT scans of their lungs to look for possible signs of lung cancer.

Sometimes radon exposure risk evaluation and lung cancer screening recommendations for that exposure are not common topics for family practitioners. Other radiation exposures and individual lung risk factors increase the difficulty of response to those with concerns. In addition to this, no authority has come forward with radon-exposure-based lung cancer screening recommendations as general guidance for the public.

Some of the most recent recommendations and resources for lung cancer screenings, lung cancer detection, and radon toxicity are listed in this fact sheet: Lung Cancer Screening for Radon Exposure. Generally, to reduce lung cancer risk the best step is to stop smoking, the next most effective measures include testing and fixing existing structures for radon and building radon-resistant new homes. 

Why is 4 pCi/L the recommended action level for Radon?

EPA recommended this mitigation action level in 1986 for several reasons. First, at lower levels (2 pCi/L) measurement devices’ false negative errors increase threefold, and false positive errors increase twofold. Secondly, mitigation research indicates that elevated levels can be reduced to 4 pCi/L or less 95% of the time. Research shows that 2 pCi/L can be achieved 70% of the time. Further, today’s mitigation technology can reduce radon levels to between 2 and 4 pCi/L most of the time. Finally, cost benefit analysis performed in 1986 indicate that an action level of 4 pCi/L results in a cost of about $700,000 per lung cancer death saved. If the action level was set at 3 pCi/L, the cost would be $1.7 million, and if set at 2 pCi/L, the cost would be $2.4 million per lung cancer death saved. EPA states that 4 pCi/L is a recommended action level, yet homeowners can further reduce their potential lung cancer risk by mitigating homes that are below 4 pCi/L.

What is the "acceptable" level of radon in air?

The EPA states that any radon exposure carries some risk; no level of radon exposure is always safe. However, the EPA recommends homes be fixed if an occupant's long-term exposure will average 4 picocuries per liter (pCi/L) or higher.

What is a "picocurie" (pCi)?

A pCi is a measure of the rate of radioactive decay of radon. One pCi is one trillionth of a Curie, 0.037 disintegrations per second, or 2.22 disintegrations per minute. Therefore, at 4 pCi/L (picocuries per liter, the EPA's recommended action level), there will be approximately 12,672 radioactive disintegrations in one liter of air during a 24-hour period.

What is a "working level" (WL)?

Some devices measure radiation from radon decay products, rather than radiation coming directly from radon. Measurements from these devices are often expressed as WL. As noted above, conversions from WL to pCi/L are usually approximate. A level of 0.02 WL is usually equal to about 4 pCi/L in a typical home.

If a working level (WL) value is converted to a radon level (pCi/L), the conversion is usually approximate and is based on a 50 percent equilibrium ratio. If the actual equilibrium ratio is determined (which is rare), it should be stated. The 50 percent ratio is typical of the home environment, but any indoor environment may have a different and varying relationship between radon and its decay products.

Technically speaking, 1 WL represents any combination of short-lived radon decay products in one liter of air that will result in the ultimate emission of 1.3 x 105 MeV of potential alpha energy.

How often is indoor radon a problem?

Nearly one out of every 15 homes has a radon level the EPA considers to be elevated—4 pCi/L or greater. The U.S. average radon-in-air level in single family homes is 1.3 pCi/L. Because most people spend as much as 90 percent of their time indoors, indoor exposure to radon is an important concern.

How does radon get into a building?

Most indoor radon comes into the building from the soil or rock beneath it. Radon and other gases rise through the soil and get trapped under the building. The trapped gases build up pressure. Air pressure inside homes is usually lower than the pressure in the soil. Therefore, the higher pressure under the building forces gases though floors and walls and into the building. Most of the gas moves through cracks and other openings. Once inside, the radon can become trapped and concentrated.

Openings which commonly allow easy flow of the gases in include the following:

  • Cracks in floors and walls
  • Gaps in suspended floors
  • Openings around sump pumps and drains
  • Cavities in walls
  • Joints in construction materials
  • Gaps around utility penetrations (pipes and wires)
  • Crawl spaces that open directly into the building

Radon may also be dissolved in water, particularly well water. After coming from a faucet, about one ten thousandth of the radon in water is typically released into the air. The more radon there is in the water, the more it can contribute to the indoor radon level.

Trace amounts of uranium are sometimes incorporated into materials used in construction. These include, but are not limited to concrete, brick, granite, and drywall. Though these materials have the potential to produce radon, they are rarely the main cause of an elevated radon level in a building.

Outdoor air that is drawn into a building can also contribute to the indoor radon level. The average outdoor air level is about 0.4 pCi/L, but it can be higher in some areas.

While radon problems may be more common in some geographic areas, any home may have an elevated radon level. New and old homes, well-sealed and drafty homes, and homes with or without basements can have a problem. Homes below the third floor of a multi-family building are particularly at risk.

Can the radon level in a building's air be predicted?

No, it is not possible to make a reliable prediction.

The only way to determine the level is to test. the EPA and the Surgeon General recommend testing all homes below the third floor for radon.

A map of radon zones has been created to help national, state, and local organizations to target their resources and to implement radon-resistant building codes. However, the map is not intended to be used for determining if a home in a given zone should be tested for radon. Homes with elevated levels of radon have been found in all three zones.

In addition, indoor radon levels vary from building to building. Do not rely on radon test results taken in other buildings in the neighborhood—even ones next door—to estimate the radon level in your building.

Contact your state radon office for information about radon in your local area. The Internet is also a source of information about radon levels in some states.

Where can I get more information about radon issues?

The National Radon Program Services at Kansas State University provides a toll-free number, (800) 767-7236. Through this automated number, callers have the options of ordering radon test kits, speaking with an information specialist, or being referred to their home state radon program. Specialists are available to assist callers between 8am to Noon, and 1pm to 5pm, Central Daylight Time on business days. They can answer specific questions and mail free, single copies of many radon documents, including the EPA booklet, Home Buyer's and Seller's Guide to Radon.

Multiple copies of many the EPA documents can be ordered through the EPA's National Service Center for Environmental Publications (NSCEP), (800) 490-9198, fax (513) 489-8695. Publication requests can also be mailed, called, or faxed directly to:

U.S. Environmental Protection Agency
National Center for Environmental Publications (NSCEP)
P.O. Box 42419
Cincinnati, OH 42419

Please use the EPA Document Number when ordering from NSCEP. Allow several weeks for delivery.

The EPA also supports operation of other related Hotlines. See the the EPA Web site for information about the following:

  • National Radon Helpline (800-557-2366) – has information specialists available to assist  consumers with more details about radon.
  • Radon FIX-IT Program Help line (800-644-6999)—assists consumers with elevated radon levels of 4 pCi/L or higher by providing information that will allow them to take the necessary steps toward fixing their homes.

In addition, the EPA also supports operation of the Safe Drinking Water Hotline, (800) 426-4791, which answers questions about radon in drinking water.

The EPA's Indoor Environments Division provides information regarding indoor air quality issues, including radon, asthma, and environmental tobacco smoke/secondhand smoke. Their radon page addresses issues including the EPA's position on radon, health risks, radon resistant new construction, and their former National Radon Proficiency Program (RPP). Many radon documents are also available there.

You can call the EPA's Safe Drinking Water Hotline, (800) 426-4791, for information on radon in water. It also provides information that can help you identify a laboratory to assist with testing drinking water.

I just found out my house has elevated radon gas levels. Should I see my physician?

Many home owners perform their first radon test after several years of occupancy. Many of these tests will return with radon values of 4 pCi/L or more. These test results often lead to questions related to medical testing or evaluation related to the previously unknown radon exposures. Currently, there is no standard medical screening test that can be used to determine if an individual has incurred genetic damage to the lung tissue that might increase risk of lung cancer across the individual’s life span. It is recommended that you inform your family physician of the radon exposure. If the physician recommends a chest x-ray to screen for lung cancer, or if it becomes medically necessary to perform a chest x-ray for other medical reasons, then this is an appropriate medical screening. But it is not recommended that an individual request a chest x-ray unless it is deemed necessary by the physician.

Do radon levels increase with the age of a home?

No. The only way to know the radon level in any home, regardless of its age, foundation type, heating system, air tightness, or building materials, is to conduct a test. Elevated radon has been found in brand new homes and homes over 150 years old.

Testing Air for Radon

Why should I test my home for radon?

Radon is widely believed to be the second leading cause of lung cancer. Therefore, the EPA and the Surgeon General recommend testing for radon in all homes below the third floor.

Radon has been found in homes all over the United States. Any home can have a radon problem. On average, one out of every fifteen U.S. homes have a problem. The only way to know whether or not your home has a radon problem is to test for it.

Who can test a building for Radon?

Anyone can use a "do-it-yourself" test kit to check their own building. The one-use kits are simple to use and are relatively inexpensive.

National Radon Program Services at Kansas State University encourages testing by offering online test kits and through the National Radon Hotline at (800) 767-7236.

Radon test kits sometimes are available in hardware stores, other retail outlets, local health departments and county extension offices. They are also available through the Internet.

EPA recommends that you hire a qualified professional to test for radon when you are buying or selling a home. Some states require radon measurement testers to follow a specific testing protocol. If you hire a contractor to test your residence, protect yourself by hiring a qualified individual or company.

You can determine a service provider's qualifications to perform radon measurements or to mitigate your home in several ways. Check with your state radon office. Many states require radon professionals to be licensed, certified, or registered. Most states can provide you with a list of knowledgeable radon service providers doing business in the state. In states that don't regulate radon services, ask the contractor if they hold a professional proficiency or certification credential.

Here are the two privately-run national radon programs who are offering proficiency listing/accreditation/certification in radon testing and mitigation. 

 

National Radon Proficiency Program
Website: www.nrpp.info
Call: (800) 269-4174 or (828) 890-4117
Fax: (828) 890-4161
E-Mail:  angel@nrpp.info

The National Radon Safety Board (NRSB)
Website: www.nrsb.org
Call: (866) 329-3474
Fax: (914) 345-1169
E-mail: info@nrsb.org

What testing protocol should be followed?

The purpose of the measurements, as well as budget and time constraints, dictate the protocol used. However, the EPA and the Surgeon General recommend testing all homes below the third floor for radon. the EPA recommends that for homes, initial measurements be short-term tests placed in the lowest lived-in level.

The protocol for measurements made for the purpose of assessing the need for mitigation (reducing the radon level) is found in the EPA publication, A Citizen's Guide to Radon. Additional guidance is provided in Section 2 of the EPA book, Protocols For Radon and Radon Decay Product Measurements In Homes.

Protocols for measurements made for real estate transactions are somewhat different. They are described in the EPA document, Home Buyer's and Seller's Guide to Radon. Additional guidance is provided in Section 3 of the EPA publication, Protocols For Radon and Radon Decay Product Measurements In Homes.

Why are short- and long-term tests used?

Radon levels within a building often change on a day-to-day basis. Highest indoor levels are often found during the heating season. Weather conditions, operation of furnaces and fireplaces, and opening/closing of windows and doors are among the factors that cause these patterns.

Short-term test kits are the quickest way to test. These kits should remain in the building from two to 90 days, depending on the device. Testing must be conducted for at least 48 hours. Some devices must be exposed for a longer time. Because radon levels tend to vary from day to day and season to season, a short-term test is less likely than a long-term test to tell you your year-round average radon level.

The EPA recommends that for homes, initial measurements be short-term tests placed in the lowest lived-in level. Short-term testing under closed-building conditions helps to ensure that residents quickly learn if a home contains very high levels of radon. If you are doing a short-term test, close your windows and outside doors and keep them closed as much as possible during the test. If testing for just 2 or 3 days, be sure to close your windows and outside doors at least 12 hours before beginning the test, too. You should not conduct short-term tests lasting just 2 or 3 days during unusually severe storms or periods of unusually high winds.

Because radon levels may fluctuate by as much as a factor of two or three, additional testing is sometimes recommended to better assess the average radon level. Though short-term tests are sometimes used, long-term tests are often recommended.

Long-term tests remain in your home for more than 90 days. A long-term test gives a reading that is more likely to reflect the building's year-round average radon level than a short-term test. Because of season variations in radon levels, the closer the long-term measurement is to 365 days, the more representative it will be of annual average radon levels.

If time permits (more than 90 days), long-term tests can be used to confirm initial short-term results between 4 pCi/L and 10 pCi/L. When long-term test results are 4 pCi/L or higher, the EPA recommends the problem be corrected.

What kinds of test devices are used?

Two groups of devices are more commonly used for short-term testing.

Passive devices do not need power to function. The group includes alpha track detectors, charcoal canisters, and charcoal liquid scintillation detectors. Some charcoal technologies are prone to interference by high humidity, so may not be appropriate for use in all buildings. They are sometimes available in drug, hardware, and other stores, the Internet, and through some laboratories. Electret ion chamber detectors, another type of short-term test device, are usually only available through laboratories. After being used, passive devices are returned to a laboratory for analysis.

Charcoal canisters for short-term use are sold through the National Radon Program Services website. These test kits are designed to be used for two or four days before being returned for analysis by the laboratory that provides it. A return mailer is provided with the kit.

Active devices require power to function. This group consists of different types of continuous monitors and continuous working level monitors. Some of the active monitors can provide data on the range of variation within the test period. Some are designed to detect and deter interference. However, they usually require operation by trained testers. These tests often cost more than passive testing.

Alpha track and electret ion chamber detectors are commonly used for long-term testing. Long-term test kits currently sold through the National Radon Program Services website are alpha-track detectors. They are designed to be used for three months to a year before being returned to the providing laboratory for analysis.

Technical information on use of various devices used to measure radon or radon decay products is found in the EPA publication, Indoor Radon and Radon Decay Product Measurement Device Protocols.

Continuous monitors are not available through the National Radon Program Services website at this time.

Where should home testing be done?

The EPA recommends that testing be done in the lowest level of the home suitable for occupancy. This typically represents an area where greatest radon level may occur. Ideally, the test should be conducted in a regularly used room on that level, such as a living room, playroom, den, or bedroom. Avoid testing in a kitchen, bathroom, laundry room, or hallway. High humidity and drafty conditions can bias results from some test devices. Do not disturb the devices while they are sampling. Doing so may alter their results, so they should be placed out-of-the-way.

If the lowest occupied level is not used much, consider also testing a higher-use area. This may help you to better estimate your long-term exposure.

Because most indoor radon comes from naturally occurring radon in the soil, high indoor levels are more likely to exist below the third floor. This is why the EPA recommends testing all homes below the third floor. In some cases, high radon levels have been found at or above the third floor, due to radon movement through elevators or other air shafts in the building. If you are concerned about this possibility, you may decide to test for radon.

More information on site selection can be found in the EPA publication, Protocols for Radon and Radon Decay Product Measurements in Homes.

If a test result is less than 4 pCi/L (0.02 WL), what should be done next?

If the result of an initial short-term measurement is below 4 pCi/L, or 0.02 WL, a follow-up test is not necessary. However, since radon levels change over time, you may want to test again sometime in the future, especially if use patterns change and a lower level of the building becomes occupied or used more often. Renovations, changes in ventilation, earthquakes, settling of the ground beneath the building, and other changes may cause indoor radon exposures to change.

If an initial short-term test result is 4 pCi/L (0.02 WL) or higher, what should be done next?

The EPA recommends a follow-up measurement be used to confirm whether radon levels are high enough to warrant mitigation. There are two types of follow-up measurements that may be conducted. The choice depends, in part, on the results of the initial test.

An initial measurement result of 10 pCi/L (or 0.05 WL) or greater should be quickly followed by a second short-term test under closed-building conditions. If the average of the initial and second short-term results is equal to or greater than 4 pCi/L (0.02 WL), radon mitigation is recommended. If the average of the short-term test results is less than 4 pCi/L, consider testing again sometime in the future.

If the result of the initial measurement is between 4 pCi/L (or 0.02 WL) and 10 pCi/L (or 0.05 WL), the follow-up test may be made with either a short-term or a long-term method. If a long-term follow-up test result is 4 pCi/L (0.02 WL) or higher, the EPA recommends remedial action. If the long-term follow-up test result is less than 4 pCi/L, consider testing again sometime in the future.

If a short-term follow-up test is done and the result is 4 pCi/L or higher, radon mitigation is recommended. If the average of the initial and follow-up short-term tests is less than 4 pCi/L, consider testing again sometime in the future.

Radon test flowchart

In certain instances, such as may occur when measurements are performed in different seasons or under different weather conditions, the initial and follow-up tests may vary by a considerable amount. Radon levels can vary significantly between seasons, so different values are to be expected.

Radon Resistant Construction

What are radon-resistant features?

radon

The techniques vary for different foundations and site requirements, but the basic elements are:

A.   Gas Permeable Layer—This layer is placed beneath the slab or flooring system to allow the soil gas to move freely underneath the house. In many cases, the material used is a 4-inch layer of clean gravel.

B.   Plastic Sheeting—Plastic sheeting is placed on top of the gas permeable layer and under the slab to help prevent the soil gas from entering the home. In crawlspaces, the sheeting is placed over the crawlspace floor.

C.   Sealing and Caulking—All openings in the concrete foundation floor are sealed to reduce soil gas entry into the home.

D.   Vent Pipe—A 3- or 4-inch gas-tight or PVC pipe (commonly used for plumbing) runs from the gas permeable layer through the house to the roof to safely vent radon and other soil gases above the house.

E.   Junction Box—An electrical junction box is installed in case an electric venting fan is needed later.

For a checklist of these items click here: RRNC Checklist (1 page, 381 KB)

For a detailed technical guide to RRNC click here: See Building Radon Out (84 pp, 5.5 MB)

When should radon-resistant construction be considered?

Find out if you are buying a home in a high radon area. the EPA's map of radon zones indicates areas having the greatest potential for elevated indoor radon readings. Homes in places with high potential, called Zone 1 areas, should be built with radon-resistant features, but the techniques can work anywhere. Also contact your state radon office to learn whether radon-resistant features are recommended or required in your area. You can also review the states and jurisdictions that require the user of these techniques at the EPA website.

If you are planning to make any major structural renovation to an existing home, such as converting an unfinished basement area into a living space, it is important to test the area for radon before you begin the renovation. If your test results indicate a radon problem, radon-resistant techniques can be inexpensively included as part of the renovation. Because major renovations can change the level of radon in any home, always test again after work is completed.

What are the benefits of radon-resistant construction?

Radon-resistant techniques are simple and inexpensive. Besides reducing radon levels, they also lower concentrations of other soil gases and decrease moisture problems. They make a home more energy efficient, and can save an annual average of $65 on energy costs.

How much does it cost to reduce radon in an existing home?

If a home with a vent system is found to have an elevated radon level, a fan can be added at a low cost. The total cost is much lower than adding the entire system after the building is completed. The average cost to install radon-resistant features in an existing home is $800 to $2,500. The average cost to install radon-resistant features in a new home during construction is $350 to $500 (a 128% to 400% saving).

Who should I hire to install radon-resistant features?

Talk to your builder about installing a radon-reduction system during major renovations or new construction. Radon-resistant features can be easily and inexpensively installed with common building practices and materials. Many builders already incorporate some of these steps in the construction of their houses to control moisture or increase energy efficiency, using either their own crews or a radon contractor. To find out about builders in your location use the EPA Directory.

Should a home built with radon-resistant features be tested?

Yes. Every new home should be tested for radon soon after occupancy and within the first year. Test your home even if it has the radon resistant features. Test kits may be available at your local hardware store, county health department or county extension office. You can also purchase short and long term test kits at www.sosradon.org. If you need more information on radon resistant new construction features visit the EPA Radon-Resistant New Construction (RRNC) website or you can contact the National Radon Hotline at 1-800-767-7236.

What are the codes or standards for radon-resistant new construction?

For details on national radon standards, or standards that relate to new homes in your area, visit the Web sites of the three organizations listed below. You can also review the states and jurisdictions that require the use of these techniques at the EPA Radon-Resistant New Construction (RRNC) website.

Are there recognized methods for testing soil gas to estimate radon potential in a future building?

Radon concentrations in soil of a site are not predictive of final concentrations in buildings constructed on that site and are a waste of resources to conduct. For planning potential radon mitigation in a new building, guidance suggests using the EPA National Radon Potential Map, pre-mitigation radon measurements in nearby existing buildings, and a review of the local jurisdiction’s code requirements for radon resistant new construction represented by appendix F of the IRC.

Radon Testing During Real Estate Transactions

What information is available regarding radon and real estate transactions?

The EPA publication Home Buyer’s and Seller’s Guide to Radon (http://www.epa.gov/radon/pubs/hmbyguid.html) details several aspects related to radon testing during real estate transactions. You can find information on radon, the protocols for radon testing during real estate transactions, and guidance as to how to interpret your radon test results.

I'm buying a house. Should I have it tested for radon?

The EPA recommends that all houses, regardless of what radon zone the house is located in, be tested for radon during point of sale. The most common procedure for radon testing during real estate transactions is for the potential buyer to request the radon test as part of the overall home inspection. The radon test is generally a separate service and must be requested. If the radon test is 4 pCi/L or greater, the EPA recommends the potential buyer negotiate with the seller to have a radon mitigation system installed with the stated goal of bringing the radon level in the home below 4 pCi/L.

I'm selling a house. Should I have it tested for radon?

The homeowner of a house can test their home prior to listing the home for sale. If the homeowner does perform a radon test, most if not all states will require that the test result be disclosed on the whole house disclosure form you will fill out with your realtor. If the initial test by the homeowner comes back less than 4 pCi/L, potential buyers may still request an additional radon test as part of their home inspection. If an initial radon test by the homeowner is 4 pCi/L or greater, the issue will need to be addressed in the real estate transaction. A buyer may want to have a confirmatory test conducted. With an average radon level of 4 pCi/L or greater, it is recommended that a radon mitigation system be installed prior to placing the house on the market, to bring the radon level to less than 4 pCi/L.

Can vacant houses be tested for radon?

Yes. Radon levels in a home, under typical operating conditions, will commonly reach a steady state with mild fluctuations about 12 hours after the house is closed up. Vacant houses will experience factors that may drive radon levels to lower or higher than normal averages, but the effect cannot be predicted. If the house is opened up for ventilation purposes prior to the test, it should then be closed up and a test started no sooner than 12 hours later. If short-term radon testing is being used, then the house has to be kept closed except for normal entry and exit, as if it were the winter heating season. It is recommended that the home’s heating and cooling system be operated normally for the season. If the average indoor level is 4 pCi/L, then it is expected that the radon level will be near to that average after 12 hours of a house being closed.

The seller of the house I want to buy disclosed a radon level of 2. Should this be a deterrent to buying?

This level should not be a deterrent to buying a home. In fact, any level should not be a deterrent to buying a home because radon can almost always be reduced in a home, and to levels below the EPA guideline of 4. Many times post mitigation tests are in the range of 1-3. The level of 2 would be a very good result for a home that had a mitigation system installed to reduce the level from a much higher number. As long as the issue is resolved in the real estate transaction, the radon level should not be a deterrent to buying any home. Achieving lower radon levels when the starting concentration is 2 to 4 is not likely to be something a radon contractor would guarantee under typical conditions for a set price.

Mitigating Radon Problems

What is a radon mitigation system?

A radon mitigation system is any system or steps designed to reduce radon concentrations in the indoor air of a building.

The EPA recommends that you take action to reduce your home's indoor radon levels if your radon test result is 4 pCi/L or higher.

What are the benefits of radon mitigation?

Radon reduction systems work. In most new homes, use of radon-resistant features will keep radon levels to below 2 pCi/L. Some radon reduction systems can reduce radon levels in your home by up to 99 percent.

Homeowners should consider correcting a radon problem before making final preparations to sell a home. This often provides more time to address the problem and find the most cost-effective solution. In addition, the current occupants—not just the buyer's occupants—will reap the benefit of reduced risk.

What can be done to reduce radon in a home?

Your house type will affect the kind of radon reduction system that will work best. Houses are generally categorized according to their foundation design. For example: basement, slab-on-grade (concrete poured at ground level), or crawlspace (a shallow unfinished space under the first floor). Some houses have more than one foundation design feature. For instance, it is common to have a basement under part of the house and to have a slab-on-grade or crawlspace under the rest of the house. In these situations a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.

There are several methods that a contractor can use to lower radon levels in your home. Some techniques prevent radon from entering your home while others reduce radon levels after it has entered. the EPA generally recommends methods that prevent the entry of radon.

In many cases, simple systems using underground pipes and an exhaust fan may be used to reduce radon. Such systems are called "sub-slab depressurization," and do not require major changes to your home. These systems remove radon gas from below the concrete floor and the foundation before it can enter the home. Similar systems can also be installed in houses with crawl spaces. Radon contractors use other methods that may also work in your home. The right system depends on the design of your home and other factors.

Sealing cracks and other openings in the floors and walls is a basic part of most approaches to radon reduction. Sealing does two things, it limits the flow of radon into your home and it reduces the loss of conditioned air, thereby making other radon reduction techniques more effective and cost-efficient. The EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently. It is difficult to identify and permanently seal the places where radon is entering. Normal settling of your house opens new entry routes and reopens old ones.

Any information that you may have about the construction of your house could help your contractor choose the best system. Your contractor will perform a visual inspection of your house and design a system that is suitable. If this inspection fails to provide enough information, the contractor will need to perform diagnostic tests to help develop the best radon reduction system for your home. Whether diagnostic tests are needed is decided by details specific to your house, such as the foundation design, what kind of material is under your house, and by the contractor's experience with similar houses and similar radon test results.

How much does it cost to reduce radon in an existing home?

The cost of making repairs to reduce radon is influenced by the size and design of your home and other factors. Most homes can be fixed for about the same cost as other common home repairs, like painting or having a new hot water heater installed. The average cost for a contractor to lower radon levels in a home is about $1,200, although this can range from $500 to about $2,500. Your costs may vary depending on the size and design of your home and which radon reduction methods are needed.

Who should I hire to correct a radon problem?

Lowering high radon levels requires technical knowledge and special skills. You should use a contractor who is trained to fix radon problems.

The EPA stopped operating its National Radon Proficiency Program (RPP) on October 1, 1998. That program was designed to test radon contractors and provide a measure of quality control. The RPP is now privately run. See the EPA's Web site regarding the RPP for information on how to identify qualified contractors.

Many states certify or license radon contractors. Call your state radon office for information about qualified service providers in your state.

If you plan to fix the problem in your home yourself, you should first contact your state radon office for the EPA's technical guide, "Radon Reduction Techniques for Detached Houses."

Will any more testing be needed after a radon mitigation system has been installed?

Most radon reduction systems include a monitor that will alert you if the system needs servicing. However, regardless of who fixes the problem, you should test your home afterward to be sure that radon levels have been reduced. This test should be conducted no sooner than 24 hours nor later than 30 days following completion and activation of the mitigation system(s). Potential conflict of interest can be avoided by using an independent tester.

In addition, it's a good idea to retest your home sometime in the future to be sure radon levels remain low. Testing should be done at least every two years or as required or recommended by state or local authority. Retesting is also recommended if the building undergoes significant alteration.

Are funds available to reduce high radon levels in rental housing?

There are some federal programs that might be used to help fund radon reduction in homes that are affordable to limited income families. These programs generally give money to local agencies or groups, which then fund the work. Some examples are:

  • Community Development Block Grant (CDBG) program—funds rehabilitation and repair of affordable housing. For more information, call the U.S. Department of Housing and Urban Development (HUD) at (202) 708-3587.
  • "203k" program—funds rehabilitation and repair of single family homes. For more information, call HUD at (202) 708-2121.
  • Environmental Justice Grants—funds community-based organizations and tribal governments addressing environmental concerns of people of color and low income communities. For more information, call the EPA's Office of Environmental Justice at (800) 962-6215.

Some states have governmental programs that can provide loans for radon reduction work in limited income housing. Some community groups are raising funds from private companies and foundations to pay for radon reduction in limited income homes.

To find out more about federal and state programs, or about how community groups have developed local projects to fix radon problems, owners and residents can contact your state radon office.

Radon in Water

How does radon get in water?

When the ground produces radon, it can dissolve and accumulate in water from underground sources (called ground water), such as wells. When water that contains radon is run for showering, washing dishes, cooking, and other uses, radon gas escapes from the water and goes into the air. Some radon also stays in the water.

Radon can be a concern if your drinking water comes from a well that draws from an underground source, though not all water from underground sources contains radon. If you get your water from a public water system that serves 25 or more year-around residents, you will receive an annual water quality report. These water quality reports include information on what is in your water, including radon if it has been tested.

Radon from lakes, rivers, and reservoirs (called surface water) is of much less concern. Most of the radon is released from the water before it enters the distribution system.

Does radon in drinking water pose a risk?

In most cases, radon entering the home through water will be a small source of risk compared with radon entering from the soil. The EPA estimates that indoor radon levels will increase by about 1 pCi/L for every 10,000 pCi/L of radon in water. Only about one to two percent of indoor radon in air comes from drinking water.

Based on a National Academy of Science report, the EPA estimates that radon in drinking water causes about 168 cancer deaths per year: 89 percent from lung cancer caused by breathing released to the indoor air from water and 11 percent from stomach cancer caused by consuming water containing radon.

Radon gas can enter the home through well water. It can be released into the air you breathe when water is used for showering and other household uses. Research suggests that swallowing water with high radon levels may pose risks, too, although risks from swallowing water containing radon are believed to be much lower than those from breathing air containing radon.

While radon in water is not a problem in homes served by most public water supplies, problems have been found in well water. If you've tested the air in your home and found a radon problem, and your water comes from a well, contact a lab certified to measure radiation in water to have your water tested. Call the EPA's Safe Drinking Water Hotline, (800) 426-4791, to get information on locating a certified lab.

If you're on a public water supply and are concerned that radon may be entering your home through the water, call your public water supplier.

Should drinking water be tested?

Because radon in indoor air is the larger health concern, the EPA recommends that you first test the air in your home for radon before testing for radon in your drinking water. the EPA and the Surgeon General recommend testing all homes for radon in indoor air (and apartments located below the third floor). The EPA recommends that you take action to reduce your home's indoor radon levels if your radon test result is 4 pCi/L or higher.

If you have tested the air in your home and found a radon problem, you may also want to find out whether your water is a concern. If you get water from a public water system, find out whether the comes from a surface (river, lake, or reservoir) or a ground water (underground) source.

If the water comes from a surface water source, most radon in the water will be released to the air before it reaches your tap. If the water comes from a ground water source, call your water system and ask if they've tested the water for radon. If so, ask for their Consumer Confidence Report.

If you have a private well, the EPA recommends testing your water for radon. The Safe Drinking Water Hotline, (800) 426-4791, can provide phone numbers for your state laboratory certification office. You can also call the National Radon Program Services Hotline, (800) SOS-RADON, for your state radon office's phone number. Your state laboratory certification office or state radon office can direct you to laboratories that are able to test your drinking water for radon.

What do the results of a water test mean?

Estimate how much the radon in your water is elevating your indoor radon level by subtracting 1 pCi/L from your indoor air radon level for every 10,000 pCi/L of radon that was found in your water. (For example: if you have 30,000 pCi/L of radon in your water, then 3 pCi/L of your indoor measurement may have come from radon in water.) If most of the radon is not coming from your water, fix your house first and then retest your indoor air to make sure that the source of elevated radon was not your private well. If a large contribution of the radon in your house is from your water, you may want to consider installing a special water treatment system to remove radon. the EPA recommends installing a water treatment system only when there is a proven radon problem in your water supply.

What levels of radon in water should I be concerned about?

There is currently no federally-enforced drinking water standard for radon.

The EPA does not regulate private wells, but is proposing to regulate radon in drinking water from community water suppliers (water systems that serve 25 or more year-round residents). the EPA proposed the rule in October 1999 and plans to finalize it in August 2000.

The EPA is proposing two options.

The first option would require community water suppliers to provide water with radon levels no higher than 4,000 pCi/L. Because about 1/10,000th of radon in water transfers to air, this would contribute about 0.4 pCi/L of radon to the air in a home. This level will be permitted if the state also takes action to reduce radon levels in indoor air by developing the EPA-approved, enhanced state radon in indoor air programs (called Multimedia Mitigation Programs). This is important because most of the radon you breathe comes from soil under the house. This option gives states the flexibility to focus on the greatest problems, encouraging the public to fix radon in indoor air problems and to build homes that keep radon from entering.

A second option is provided for states that choose not to develop enhanced indoor air programs. Community water systems in those states will be required to reduce radon levels in drinking water to 300 pCi/L. This amount of radon in water contributes about 0.03 pCi/L of radon to the air in your home.

Even if a state does not develop an enhanced indoor air program, water systems may choose to develop their own local indoor radon program. This will require them to meet a radon standard for drinking water of 4,000 pCi/L. This option enables overall risks from exposure to radon, both through air and water, to be reduced.

How is radon removed from water?

Radon can be removed from water by using one of two methods: aeration treatment or granular activated carbon (GAC) treatment.

Aeration treatments involve bubbling air through the water. This helps to strip radon from the water. An exhaust fan is used to vent the radon outdoors.

GAC treatment filters water through carbon. Radon attaches to the carbon and leaves the water free of radon. GAC filters tend to cost less than aeration devices. However, radioactivity collects on the filter and may cause a handling hazard and require special disposal methods for the filter.

For more information on aerators and GAC filters, you should contact two independent, non-profit organizations: NSF International at (800) 673-8010 and the Water Quality Association at (630) 505-0160.

In either treatment, it is important to treat the water where it enters your home (point-of-entry device) so that all the water will be treated. Point-of-use devices, such as those installed on a tap or under the sink, will only treat a small portion of your water and are not effective in reducing radon in your water.

It is important to maintain home water treatment units because failure to do so can lead to other water contamination problems. Some homeowners opt for a service contract from the installer to provide for carbon replacement and general system maintenance.