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Radon Testing

NJ DEP Radon Measurement

Technician License MET #12036 

Licensed by the New Jersey Department of Environmental Protection

Radon, one of nature’s 92 naturally occurring elements, is a radioactive gas. It is formed naturally by the decay of the uranium that exists in most soils. It is odorless and colorless, making it difficult to detect but no less dangerous. Federal agencies estimate that radon gas causes at least 15,000 to 22,000 lung cancer related deaths annually. Radon is a leading cause of lung cancer, second only to cigarette smoking. Radon gas moves up from the ground and into buildings through cracks, holes, and gaps present in nearly every foundation and basement floor. Once inside the building, the radon collects on the lower levels where it can exist in dangerous concentrations. The Environmental Protection Agency and most state agencies have stated that any indoor radon concentration that exceeds 4.0 pCi/L should be reduced. 1 out of every 15 buildings in the United States has elevated levels. Old or new, well‐sealed or not, all buildings are at risk of radon build up. As dangerous as radon can be, mitigation can provide a very effective, low cost means to restore the safety of your home.


Radon is a carcinogenic gas that is hazardous to inhale. Build-up of radon in homes is a health concern and many lung cancer cases are attributed to radon exposure each year. About 12% of lung cancers and more than 20,000 Americans die of radon-related lung cancer each year. The Surgeon General of the United States has issued a Health Advisory warning Americans about the health risk from exposure to radon in indoor air. Dr. Carmona, the, Nation’s Chief Physician urged Americans to test their homes to find out how much radon they might be breathing. He also stressed the need to remedy the problem as soon as possible.You cannot see, smell, or taste radon. But it still may be a problem in your home. When you breathe air containing radon, you increase your risk of getting lung cancer. In fact, the Surgeon General of the United States has warned that radon is the second leading cause of lung cancer in the United States today. If you smoke and your home has high radon levels, your risk of lung cancer is especially high.


Testing is the only way to find out your home’s radon levels. EPA and the Surgeon General recommend testing all homes below the third floor for radon. If you find that you have high radon levels, there are ways to fix a radon problem. Even very high levels can be reduced to acceptable levels. Radon has been found in homes all over the United States. It comes from the natural breakdown of uranium in soil, rock and water and gets into the air you breathe. Radon typically moves up through the ground to the air above and into your home through cracks and other holes in the foundation. Radon can also enter your home through well water. Your home can trap radon inside.Any home can have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements. In fact, you and your family are most likely to get your greatest radiation exposure at home. That is where you spend most of your time. Nearly 1 out of every 15 homes in the United States is estimated to have an elevated radon level. Elevated levels of radon gas have been found in homes in your state.


EPA’s Radon Testing Check List:

Notify the occupants of the importance of proper testing conditions. Give the occupants written instructions or a copy of this Guide and explain the directions carefully.


Conduct the radon test for a minimum of 48 hours; some test devices have a minimum exposure time greater than 48 hours.


When doing a short-term test ranging from 2-4 days, it is important to maintain closed-house conditions for at least 12 hours before the beginning of the test and during the entire test period.


When doing a short-term test ranging from 4-6 days, EPA recommends that closed-house conditions be maintained.


If you hire someone to do the test, hire only a qualified individual. Some states issue photo identification (ID) cards; ask to see it. The tester’s ID number, if available, should be included or noted in the test report.


The test should include method(s) to prevent or detect interference with testing conditions or with the testing device itself.


If the house has an active radon-reduction system, make sure the vent fan is operating properly. If the fan is not operating properly, have it (or ask to have it) repaired and then test.


If your home has not yet been tested for Radon have a test taken as soon as possible. If you can, test your home before putting it on the market. You should test in the lowest level of the home which is suitable for occupancy. This means testing in the lowest level that you currently live in or a lower level not currently used, but which a buyer could use for living space without renovations.


The radon test result is important information about your home’s radon level. Some states require radon measurement testers to follow a specific testing protocol. If you do the test yourself, you should carefully follow the testing protocol for your area or EPA’s Radon Testing Checklist. If you hire a contractor to test your residence, protect yourself by hiring a qualified individual or company.


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. Such programs usually provide members with a photo-ID card, which indicates their qualification(s) and its expiration date. If in doubt, you should check with their credentialing organization. Alternatively, ask the contractor if they’ve successfully completed formal training appropriate for testing or mitigation, e.g., a course in radon measurement or radon mitigation.

If you are thinking of selling your home and you have already tested your home for radon, review the Radon Testing Checklist to make sure that the test was done correctly. If so, provide your test results to the buyer.

No matter what kind of test you took, a potential buyer may ask for a new test especially if:


The Radon Testing Checklist items were not met;


The last test is not recent, e.g., within two years;


You have renovated or altered your home since you tested; or


The buyer plans to live in a lower level of the house than was tested, such as a basement suitable for occupancy but not currently lived in.


A buyer may also ask for a new test if your state or local government requires disclosure of radon information to buyers.


Radon Myths and Facts


MYTH: Scientists are not sure that radon really is a problem.


FACT: Although some scientists dispute the precise number of deaths due to radon, all the major health organizations (like the Centers for Disease Control and Prevention, the American Lung Association and the American Medical Association) agree with estimates that radon causes thousands of preventable lung cancer deaths every year. This is especially true among smokers, since the risk to smokers is much greater than to non-smokers.


MYTH: Radon testing is difficult, time-consuming and expensive.


FACT: Radon testing is easy and inexpensive.


MYTH: Radon testing devices are not reliable and are difficult to find.


FACT: Reliable testing devices are available from qualified radon testers and companies.


MYTH: Homes with radon problems can’t be fixed.


FACT: There are simple solutions to radon problems in homes. Hundreds of thousands of homeowners have already fixed radon problems in their homes. Radon levels can be readily lowered for $800 to $2,500 (with an average cost of $1,200).


MYTH: Radon affects only certain kinds of homes.


FACT: House construction can affect radon levels. However, radon can be a problem in homes of all types: old homes, new homes, drafty homes, insulated homes, homes with basements, and homes without basements. Local geology, construction materials, and how the home was built are among the factors that can affect radon levels in homes.


MYTH: Radon is only a problem in certain parts of the country.


FACT: High radon levels have been found in every state. Radon problems do vary from area to area, but the only way to know your radon level is to test.


MYTH: A neighbor’s test result is a good indication of whether your home has a problem.


FACT: It’s not. Radon levels can vary greatly from home to home. The only way to know if your home has a radon problem is to test it.


MYTH: It’s difficult to sell homes where radon problems have been discovered.


FACT: Where radon problems have been fixed, home sales have not been blocked or frustrated. The added protection is some times a good selling point.


MYTH: I’ve lived in my home for so long, it doesn’t make sense to take action now.


FACT: You will reduce your risk of lung cancer when you reduce radon levels, even if you’ve lived with a radon problem for a long time.


MYTH: Short-term tests can’t be used for making a decision about whether to fix your home.


FACT: A short-term test, followed by a second short-term test* can be used to decide whether to fix your home. However, the closer the average of your two short-term tests is to 4 pCi/L, the less certain you can be about whether your year-round average is above or below that level. Keep in mind that radon levels below 4 pCi/L still pose some risk. 


What is Radon & Why is it a concern?

Radon is a radioactive gas that comes from the breakdown of naturally occurring uranium in soil and rock. It is invisible, odorless and tasteless, and can only be detected by specialized tests. Radon enters homes through openings that are in contact with the ground, such as cracks in the foundation, small openings around pipes, and sump pits.

Radon, like other radioactive materials, undergoes radioactive decay that forms decay products. Radon and its decay products release radioactive energy that can damage lung tissue in a way that causes the beginning of lung cancer.

The more radon you are exposed to, and the longer the exposure, the greater the risk of eventually developing lung cancer. Radon is the second leading cause of lung cancer in the United States, resulting in 15,000 to 22,000 deaths per year.

Testing your home for radon is easy and homes with high levels of radon can be fixed (mitigated). The New Jersey Department of Environmental Protection (DEP) recommends that all homes be tested for radon.


Homeowners can test for radon themselves or hire a New Jersey certified radon measurement company to perform the testing. Some certified radon measurement companies sell test kits, and test kits are often available in hardware stores or from local health departments. A list of certified companies, including companies that can mail you a "do-it-yourself" test, is available through the NJDEP Radon Program’s Information Line, (800)648-0394, or web site,

If you buy your test from a retail store, make sure that the kit is labeled with the New Jersey certification number of the company that produced the test kit (the number will begin with "MEB9’" followed by 4 digits), or you can call the Information Line to confirm that the company is certified. If you hire a contractor to do the test, make sure the technician who places and picks up the test device is certified by the State, by checking their NJDEP certificate or calling the Radon Information Line. It is against the law to do radon testing or mitigation without certification in New Jersey.

Short-Term Tests:

A single short-term test of 2-7 days in length can be used to indicate the radon level in your home. If a single short-term test reveals levels of 4 pCi/L or more, DEP data indicate that subsequent testing would confirm that levels in the home are 4 pCi/L or more in 80 percent of cases. If a second short-term test is conducted in the same location (either simultaneously or at different points in time), and the results of the tests are averaged, the average will provide a slightly more accurate estimate of radon levels.

A variety of short-term test devices are available, including charcoal canisters, electrets, and continuous radon monitors. The DEP Radon Program considers all short-term test devices used by certified companies to be equally reliable.

Long-Term Tests:

A long-term test of 3-12 months will provide your best estimate of average exposure over time, since radon levels fluctuate daily and by season. Because gases are drawn to areas of lower pressure, radon gas will enter the home at a rate that depends on the air pressure inside the home, which is affected by temperature, wind conditions, exhaust systems in the home, etc. Long-term testing should include the winter months, when radon concentrations are often higher than at other times.

Long-term test devices are usually either alpha track detectors or electrets; both tests are considered equally reliable and accurate.

Real Estate Transactions:

A single short-term radon test may be used for real estate transactions. An escrow account, with funds set aside by the seller, can be arranged for the buyer who prefers to test after closing. The funds can then be used to mitigate the home if testing reveals concentrations of 4 pCi/L or more.

If you are a potential homebuyer and are concerned about the possibility of test tampering, discuss anti-tampering methods with the radon measurement contractors you are considering hiring. Also, be sure to check that the contractor will close and pick up the test, as required by regulation. Neither the buyer, the homeowner nor the real estate agent can perform any part of the test, including: closing the test, picking it up, or sending it to a laboratory. If a homeowner is testing their home for themselves, they may do all or part of the test.


If you do the test yourself, the process is very simple. You need only follow the testing instructions and complete the form that accompanies the test device. The device should then be mailed without delay to a laboratory using a pre-addressed envelope enclosed with the kit.

The following guidelines should be used by both homeowners and measurement companies.

For both long-term and short-term tests, the testing device must be placed:

  • In the lowest livable level of the home -- that is, the lowest level of the home that is used, or could be used, as a living space. This would include, for example, a first floor without a basement, and a finished or unfinished basement, but not a crawl space.

  • In a location where it will not be disturbed.

  • At least 20 inches from the floor, at least 4 inches away from other objects and at least 36 inches away from doors, windows or other openings to the outside. The tests only need to be placed one foot away from exterior walls that have no openings. If suspended from the ceiling, it should be in the general breathing zone.


Test kits should not be placed:

  • In areas exposed to direct sunlight, drafts, high heat, or high humidity; or

  • In kitchens, bathrooms, laundry rooms or closets.


In addition, attic and window fans, fireplaces and wood stoves (unless they are the primary heat source) should not be used for the duration of the test. They will affect air pressure in the house which will in turn affect radon concentrations. Air conditioning can be used if it circulates inside air rather than bringing in air from the outside.

For short-term tests, it is very important to maintain "closed house conditions," since ventilation can increase or decrease radon levels in unpredictable ways. This means all windows and doors that let in outside air, on all floors, must be kept closed except for normal entrances and exits. You need to maintain closed house conditions until the short-term test is finished. For tests that last less than four days, closed house conditions must be started at least 12 hours before you begin the test.


The test report will usually give your radon reading in picoCuries per liter (pCi/L). PicoCuries per liter is a measure of how much radiation is in a liter of air, which is about the size of a quart. Sometimes results will be given in Working Levels (WL). You can calculate the pCi/L level by multiplying the WL reading by 200.

The DEP and the Environmental Protection Agency (EPA) both recommend that you take action to mitigate your home if your test results indicate radon levels of 4.0 pCi/L of radon or more. If you used two or more short-term tests at the same location, the results should be averaged.

There is no truly "safe" level of radon since lung cancer can result from very low exposures to radon – however, the risk decreases as the radon concentration decreases. If your test result is less than 4.0 pCi/L, you may want to discuss with mitigation companies whether the radon level can be brought down still further. In about half of the homes that have been mitigated in New Jersey, radon levels have been brought to less than 1 pCi/L.

Radon Risk for Smokers and Nonsmokers

(Source: National Academy of Sciences, Biological Effects of Ionizing Radiation, Sixth Report, 1998)


Odds for smokers* of developing lung cancer due to radon if exposed to this level over a lifetime**


Radon Level (in pCi/L)      Odds for non-smokers* of                          Odds for smokers* of

                                           developing lung cancer due                   developing lung cancer due to

                                              to radon if exposed to this                  radon if exposed to this level

                                                level over a lifetime                                    over a lifetime    

20                                               1 in 27                                                             1 in 5

8                                                 1 in 68                                                             1 in 13

4                                                 1 in 135                                                           1 in 26

2                                                 1 in 270                                                           1 in 52

0.4***                                          1 in                                                                  1,3501 in 260  




    *Smokers are defined as individuals who have smoked at least 100 cigarettes in a lifetime; non-smokers have never smoked or smoked
      less than 100 cigarettes in a lifetime.
    **This is in addition to the risk of lung cancer from smoking itself.
    ***Average outdoor radon concentration.


The most common type of radon mitigation system is the sub-slab depressurization system. This system uses venting and sealing to lower radon levels in the home. A pipe is installed that runs from below the basement flooring to above the roofline, with a fan at the top that draws radon out from under the slab. Cracks and openings in the foundation are sealed. The radon is vented through the pipe to the outside, where it is quickly diluted.

The average price of such a system is around $1,200, although prices can range from $500 to $2,500, depending on characteristics of the home and the underlying soil. You can install the system yourself, if you are highly experienced in making home repairs, or you can hire a New Jersey certified radon mitigation company to do the work for you. New Jersey certified radon mitigation professionals meet specified education and experience standards and must take continuing education classes each year to maintain their certification. It is against the law for uncertified contractors to do mitigation work in New Jersey.

After your home has been mitigated, make sure the mitigator does a post-mitigation test to prove the system is working properly. In addition, you can contact the Radon Program to obtain a free post-mitigation test (you will have to provide a copy of your mitigation contract). Retesting your home every two years will tell you whether or not your system is still working effectively in reducing the radon level to below 4 pCi/L. If you believe that your system was not installed correctly, you can contact the Radon Program to arrange for a free inspection and test of the system.


Feel free to contact the DEP Radon Program if you have any questions, if you’d like a copy of the certified radon businesses lists, or if you have complaints about services provided by radon companies, through the Information Line at (800)648-0394 (within New Jersey) or (609)984-5425 (outside New Jersey) -- or you can visit the Radon Program web site at

Our Radon Testing Kit

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