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Click each question for the answers. This page is updated periodically from queries we receive online. Be sure you check out our Radon Facts page for some general and scientific facts. If you need more information, try our Radon Links page.

1. What is the 'acceptable' level of radon?
The US EPA has established the "action level" for deciding when you need to "do something" about the radon in your home, school, or work place is 4 pCi/l.

Read more about the difference between "safe" and "acceptable" radon levels.

pCi/l= pico curies per liter, the most popular method of reporting radon levels. For those interested in the numbers, a pico curie is 0.000,000,000,001 (one-trillionth) of a Curie, an international measurement unit of radioactivity. One pCi/l means that in one liter of air there will be 2.2 radioactive disintegrations each minute. For example, at 4 pCi/l there will be approximately 12,672 radioactive disintegrations in one liter of air, during a 24-hour period.

4 pCi/l is the level accepted by most states and US territories

In other countries, the action level ranges from 150 Bq m3, which is slightly less than 4 pCi/l, to no limit or preset action level. For example, in Canada the suggested action level is 200 Bq m3.

Bq=becquerels is an international method of measuring radiation. View a conversion schedule.

You can read or download a copy of the US EPA's A Citizen's Guide to Radon, which goes into greater detail on the meaning of your radon test results and your personal hazard from exposure to radon.

Opinions vary on what the action level should be. See the US EPA's official position at the EPA's Radon Health Risks Frequently Asked Questions.

2. What do you do when you find high radon levels in your home?

First, have you re-tested to confirm that the radon levels are actually too high? (Do you have an average of over 4 pCi/l from the results of two or more short-term tests or from one long-term test of 90 days or more?)

If you have, then are you going to try and fix the problem yourself? If so, view the US EPA slide show on our site. You may also want to order Doug Kladder's book, Protecting Your Home From Radon. Doug and his team helped the US EPA put together their radon mitigation training course and they also developed the EPA's slide show. Kladder's book is the most complete source of information on radon mitigation techniques currently available. See the Table of Contents.

If you are looking for Do-it-Yourself radon mitigation help, Infiltec and Dave Saum can help with advice, supplies, and pricing. Their Mitigation FAQ is an excellent source of radon mitigation information. Dave and his partner Mark Messing have been influential in helping the US EPA establish radon mitigation standards. Dave's direct line is (703) 820-7696 or visit their web site.

If you intend to hire a contractor, the cost will likely range between $700 to $2500, according to the size of the building and other factors. You may want to call your state radon officer and ask for a list of approved "Radon Mitigation Contractors."

If you want to locate an NEHA-certified mitigation contractor yourself, you may consult a list of Residential Radon Mitigation Service Providers. We do NOT endorse any of these service providers and we suggest getting more than one estimate.

For some official guidance on correcting your home's radon problem, check out the EPA's Consumer's Guide to Radon Reduction. You can also call the Radon Fix-it Line operated by Kansas State University in partnership with the EPA at 1-800-644-6999. They provide guidance and encouragement to consumers with elevated radon levels and will try to answer some of your most pressing questions.

3. I'm thinking about buying a home with a radon mitigation system in place. How do I know it is working properly?

Get a basic idea of what to look for by viewing the US EPA slide show. See Unit Three for system design and other details.

You may also call a licensed radon mitigation contractor to have the system inspected. You can get a list of approved contractors from your state radon officer.

4. What are the advantages or disadvantages to having a radon mitigation system?

If the system is installed correctly and it is operating properly, the primary advantage is that you will have lower in-home radon levels.

Depending on the type of mitigation system, a secondary advantage is a much lower level of humidity (dampness) inside the building, especially in houses with basements or slab-on-grade floors. If the system is an active "sub-slab-suction" design or has incorporated a vapor barrier over the bare soil, then reduced humidity may occur. In many cases, we have heard of folks getting rid of their dehumidifier after seeing how dry the basement became after switching on their mitigation system.

One of the disadvantages is that you will pay a small energy penalty with an active design because of the energy required to run the small fan. Most will only draw about 50 watts. There is also a small loss of inside (conditioned) air that you may have paid to heat or cool. In poor installations, you may be able to hear the fan running. Fortunately, this complaint is seldom heard and if it is, generally easy to fix.

5. We are thinking of selling our house and buying another. Where can we get some guidance on what to do about a potential radon problem at either location?

Download or read the EPA's Home Buyer's and Seller's Guide to Radon. This pamphlet is loaded with testing suggestions and other information.

6. How do you test for radon? Can I do it myself?

You can test for radon yourself or call a professional home inspector who offers a radon testing service. The cost to have a professional conduct your radon test may run as high as $300.00, according to where you live.

If you conduct the radon test yourself, DIY test kits may be found at your local hardware store or home center. The average retail price runs from $20 to $30.

You can also order a test kit from our website or by calling 800-AIR-CHEK. Our DIY test kits are very easy to use, as you can see from this short instructional animation of our kits. (Video takes about a minute to load.)

7. What are the most commonly used radon testing methods?

There are two main methods used to test for radon gas and radon daughter products. The most popular involves a "passive" device such as an activated charcoal test kit that collects radon gas atoms or an alpha track device that has a small strip of special plastic that is "marked" when hit by radon's alpha particles. "Passive" devices are later "counted" in a laboratory to give you your result. Another passive device called an electret has a plastic disc with a static charge. Electrets are used only by professional radon inspectors because of the expertise required and the expensive equipment needed for analysis.

The other main method is the use of an "active" device called a CRM (continuous radon monitor). These are mostly used by professional radon inspectors for short-term (48 hours) radon testing during a real estate transaction. There are many different models of CRMs, but they all require some formal training in order to be used properly.

The biggest differences between passive and active radon testing methods are the cost and the level of expertise required for proper operation. The only devices suitable for the do-it-yourself radon tester are the activated charcoal test kits and the alpha track detectors. It is estimated that nearly 95% of all radon testing is conducted with activated charcoal test kits. Simplicity, ease of use, and low cost are the reasons more than 250,000 of these devices are used by the general public each year to test their homes and work places. Their typical purpose is to provide a radon screening measurement by homeowners who want to know if there is a potential radon problem in their home.

The US EPA has established a guideline for do-it-yourself radon test kit accuracy of +/- 25%. This equates to +/- 1 picocurie at the EPA's action level of 4 picocuries per liter of air in the home. This level of accuracy is easily accomplished when using most do-it-yourself devices, IF the user carefully follows the instructions.

8. How does the Air Chek test kit work? Is it difficult to use?

Air Chek's test kit is an activated charcoal device. Operation is neat, quick and simple. Follow this link to read more about it and to see an animation of how to use it. For more in-depth test kit placement instructions, read our Testing FAQ.

We have processed over a million test samples sent by first-time users of a radon test kit. Our kits have a high success rate of over 95%. Most problems occur simply because the user did not read the instructions or got in a hurry and forgot to seal the kit before shipping it to the lab.

9. Where can I buy an Air Chek test kit locally?

To keep our prices low, our most popular do-it-yourself 3 to 7 day test kit is not carried in retail stores. However, most state and local health departments stock our kits at very competitive prices (and some give them away for free). Another local source may be your area's ALA (American Lung Association).

You can also order a test kit from our website using your VISA, MC, Discover or AMEX card. Small orders with our free standard shipping are processed two to three times per week and are sent via third class mail. Larger quantities or requests for express delivery submitted by 12:00 noon EST, Monday to Friday, are shipped the same day via FedEx Ground. If you are in a really big hurry, call our toll-free number at 800-AIR-CHEK (247-2435) to ask about FedEx shipping options. We can also send up to 6 test kits using USPS Priority Mail for only $5.85.

10. Where can I get some information on radon in water or buy a radon-in-water test?

Most areas of the US do NOT have a radon-in-water problem. Therefore you should contact your state radon office before concerning yourself with this hazard.

The following is an excerpt from the US EPA's Citizen's Guide to Radon:


If you've tested the air in your home and found a radon problem, and your water comes from a well, you should have your water tested for radon.

Compared with radon entering the home through soil, radon entering the home through water will in most cases be a small source of risk. 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, it has 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.

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

Radon problems in water can be readily fixed. The most effective treatment is to remove radon from the water before it enters the home. This is called point-of-entry treatment. Treatment at your water tap is called point-of-use treatment. Unfortunately, point-of-use treatment will not reduce most of the inhalation risk from radon.

Call your State Radon Contact or the EPA Drinking Water Hot line (800-426-4791) for more information on radon in water.

If you would like to test for radon in water, you can order a DIY radon-in-water test kit.

11. What method of analysis does Air Chek use to determine radon concentration?

For information on Air Chek's analysis procedures, go to our page on Radon Analysis Procedures

12. Are there other symptoms or health problems other than lung cancer that are associated with radon gas exposure?

We receive this question from a lot of folks who have been suffering from various health problems. The basic answer is that there has never been documentation of any short-term radon exposure symptoms, at least not at the radon levels you are likely to see in a home, school, or office. Also, YOU WILL NOT HAVE ANY OTHER bodily symptoms such as joint pain, stomach or intestinal problems, headaches, or rashes from short-term radon exposure at natural environmental levels.

It will take years of exposure at relatively high levels before you are likely to have ANY symptoms and even then, the only known (documented) symptoms are the same as those listed for smoking-induced Lung Cancer Symptoms.

13. How great are my chances of getting lung cancer from radon?

This is still subject to debate. To view a Radon-Lung Cancer study conducted by Air Chek, go to A Lung Cancer Study. Also, see other sources of information on our Radon Links page.

14. Where can I get copies of the EPA's publications about radon?

We've compiled a list of US EPA pamphlets from their web site. The most popular is A Citizen's Guide to Radon..

If you have further questions about Radon, please call your State Radon Contact or the National Radon Information Line at: 1-800-SOS-RADON (767-7236) or The Radon FIX-IT Program at: 1-800-644-6999.

The Radon Fix-it Line provides guidance and encouragement to consumers with elevated radon levels of 4 pCi/L or higher to take the necessary steps toward fixing their homes.

15. Is there a map showing the radon levels for the US?

Visit our Radon Map for data based on actual test results.

16. Where can I find some information about other types of radiation?

The Radiation Information Network site is maintained for the use by anyone with interests in radiation. All of the material has been reviewed and is believed to represent the current consensus of facts on radiation and radiation protection.

17. Does radon come from building materials?

There may be a few building materials that will emit small amounts of radon gas, such as granite, concrete, gypsum board (sheet rock), bricks, and field stone. However, this is RARELY the case because most of these materials are very dense. This means that if there is radon-producing radium in these materials, only a small amount of the radon gas near the surface ever makes it out into the environment. Most of the radon gas decays while trapped below the surface. Radon gas has an approximately 92 hour half-life and in 8 half-lives, most of it is "dead."

In almost all cases of elevated indoor radon levels, the culprit is the underlying soil. We have heard of a few homes whose walls are built entirely of stone that have almost NO indoor radon. We have also heard of a few that have elevated levels. It is not easy to determine if the radon is coming from only the walls or if it is a combination of the walls and the underlying soil. To know for certain requires a skillful tester using expensive equipment.