Frequently Asked Questions

Radon FAQs

Radon Frequently Asked Questions

What is radon and where does it come from?

Radon is a colorless, odorless and tasteless radioactive gas that is formed by the decay of uranium in soil, rock and water. It is naturally occurring and exists at low levels everywhere. Nationwide, the average outdoor radon level is 0.4 pCi/L and the average indoor level is 1.3 pCi/L. Radon travels through the soil, upward toward open air above the ground. Some remains within the soil and dissolves in water that collects and flows as ground water.

Radon has a half life of approximately four days. This means radon decays by one half every four days. This decay process produces very short lived radioactive by-products that can attach to dust and other particles that can be inhaled.

What is a picocurie (pCi)?

A pCi is a measure of the rate of radon decay. It equates to 2.22 radioactive disintegrations/minute. Measured radon levels are reported in pCi/liter of air per day. Therefore, a measurement of 4 pCi/L represents approximately 12,672 radioactive disintegrations per one liter of air over a twenty four hour period.

Is any radon level considered acceptable?

Radon has been classified as a class A carcinogen. According to the EPA, no radon level can be considered 100% safe. However, it is naturally occurring everywhere and cannot be completely eliminated. The EPA has established 4pCi/L as an “acceptable” level and recommends that homes be mitigated if the occupant will experience long term exposure to radon levels above an average of 4 pCi/L.

What health effects are associated with radon exposure?

Radon exposure has been undeniably linked to an increased lung cancer risk. It is recognized as the second leading cause of lung cancer and the number one cause of non-smoking related lung cancer. The EPA estimates that radon is responsible for approximately 21,000 lung cancer deaths in the United States each year. Smoking combined with radon exposure increases an individual’s lung cancer risk dramatically.

In 2005, the US Surgeon General issued this health warning regarding the risks of radon exposure. "Indoor radon is the second-leading cause of lung cancer in the United States and breathing it over prolonged periods can present a significant health risk to families all over the county. It's important to know that this threat is completely preventable. Radon can be detected with a simple test and fixed through well-established venting techniques."

Radon gas decays to minute radioactive by-products that attach to dust and get trapped in lung tissue. These particles may cause tissue damage that leads to the development of lung cancer over time.

Radon does NOT cause short-term respiratory health effects. However prolonged periods of coughing or shortness of breath may indicate the need for screening for signs of lung cancer.

How often is radon found at unacceptable levels?

In the United States overall, it is estimated that 1 in 15 homes has radon above 4.0 pCi/L.

How often is radon a problem in Pennsylvania?

In Pennsylvania, it is estimated that approximately 40% of all homes have elevated radon levels above 4.0 pCi/L. Because most people spend the majority of their time at home, residential radon levels are a serious health concern. You can learn the average radon level that has been reported to the PA Department of Environmental Protection for your area by entering your zip code here. However, you cannot assume your radon level based on those in the surrounding area. The only way to know if you are exposed to radon is to test your home.

Can the radon concentration in a building be estimated or predicted?

It is impossible to accurately estimate or predict the level of radon in any home or building. Many factors affect the radon level in a structure. Aside from the radon concentration in the soil, certain structural elements of the building allow radon to enter. Some potential entry points are cracks in the foundation, structural joints, sump pits, entry penetrations for utilities, perimeter drains, floor drains and unsealed crawl spaces. One cannot assume that the radon levels of neighboring homes are an accurate radon indicator. However, if neighboring homes are reported to have high radon levels, testing of every home in the area is strongly indicated. A radon test is the only way to determine the radon concentration in any building.

Does the type of home affect the radon level?

Any type of home can have a significant radon problem. Some people are under the misconception that they are “safe” in an older drafty home or in a home without a basement. “Leaky” homes can actually pull more radon in through the foundation as warm air escapes the building. Newer energy efficient homes allow for less air exchange and radon becomes trapped within the house. If a home has a slab foundation, radon below the slab can get pulled directly into the living space1 Every home should be tested for radon regardless of size, age, air tightness, or type of foundation. Even new homes that include a passive radon system should be tested. Often these systems require activation to adequately mitigate the sub-soil radon accumulation.

Does the radon level in my home fluctuate?

The radon level in a home may fluctuate. Weather and temperature have a strong influence on the amount of radon that is being pulled into a home at any given time. It can vary hour-by-hour, day-to-day, and season-to-season. Radon levels tend to be highest in winter when your home is sealed against the weather and the temperature variations between the interior and exterior of the house are greatest. This makes winter a good time for testing your home to ensure a safe level year round.

If you have installed a radon monitor in your home, you should not be alarmed if it occasionally registers above 4.0 pCi/L. Make sure your monitor is set to average radon levels to give a true indication of your overall radon exposure.

Who can conduct a test for radon?

Do-it-yourself radon test kits are readily available and are an affordable and accurate way to determine your current radon level. It’s very important that you read the easy to follow instructions carefully and forward the test kit for analysis immediately when the test period is complete.

As an alternative, some home inspection and radon mitigation companies offer radon testing services. If you decide to hire a professional, be sure to verify that the individual holds the industry certifications that qualify him for professional radon measurement. A professional test may be conducted using test kits similar to those you can do yourself, or may involve the use of a continuous radon monitor.

Does a new home with a passive radon system need to be tested for radon?

All homes should be tested for radon. A correctly installed passive radon system consists of a straight pipe that runs through an interior wall of the home from a radon collection point below the foundation through an opening in the roof. These systems depend on the warming influence of the air in the home pulling air (and radon gas) from below the foundation and venting it above the house. While passive systems help to reduce radon levels, they often are insufficient to reduce the radon to acceptable levels.

When a passive system is inadequate, the system can be easily and affordably activated. A radon technician will open the system and inspect the pit below the house to ensure that it has a sufficient collection chamber. He will then mount a radon fan in the attic of the home to create a vacuum to pull the radon from below the foundation. In some cases (where radon levels are high) it may be necessary to install a second collection point in order to create enough negative pressure below the foundation.

Radon resistant systems work in situations where radon levels are low and where the soil below the foundation allows for air and gas to flow freely. The existence of a passive system in a home does not guarantee safe radon levels. It is very important that homes with passive radon systems be tested and it is recommended that they be retested with regularity (every two years).

How is radon testing conducted?

A radon test is conducted by exposing a testing device to the air in a home for a prescribed period of time. The EPA provides a thorough description of the testing process in the Citizens Guide to Radon ( The placement of the testing device is important to ensuring accurate results. The test device should be left undisturbed and it is also important that closed building conditions be maintained throughout the test. For complete details regarding radon testing, please consult the Citizen’s Guide to Radon. (

What do my test results mean and what happens next?

If your test returns a result below 4.0 pCi/l, your home is does not currently contain dangerously high levels of radon. It’s important to note that radon levels can change. The EPA recommends that homes be retested every two years. If there is construction nearby or if structural modifications are made to or around the home, radon levels may be affected.

If your test results are above 4.0 pCi/L, mitigation may be indicated. You should consult with a radon remediation company that is licensed with the state Department of Environmental Protection. A radon professional can advise you on conducting additional testing to verify your results or recommend a radon remediation system appropriate for your home.

What factors can affect the results of a radon test?

Closed building conditions should be maintained during a radon test. For tests of short duration (less than 4 days), the closed conditions should be maintained as least 24 hours prior to the testing period. Closed building conditions means all doors and windows are kept closed except to allow entry or exit. Ventilation that recirculates inside air may be used but no fresh air should be introduced.

The test device should be placed in a location where it will not be disturbed and should not be moved during the testing period. It should be located away from exterior walls and all doors or windows. Radon test devices are sensitive to humidity so they should not be located in a kitchen, laundry area or bathroom. They can also be affected by changes in weather. Periods of strong prolonged winds or severe weather can invalidate a radon test. A full description of factors can be found in the EPA Citizen’s Guide to Radon. (

Will opening the windows reduce the radon level in my house?

Opening windows often will increase the radon level in a building. As warm air exits the building through the window, replacement air must be pulled in from a lower level. This often pulls air into the house from below the foundation. This air may be contaminated with radon gas.

What is the cost of a radon mitigation system?

For most homes, a radon mitigation system is no more expensive than other moderate home repairs or improvements. In most cases a homeowner should expect to pay between $800 and $1200 dollars for a full installation.

What factors are considered when determining the best radon system for my home?

Radon mitigation is not “one size fits all”. Several factors must be considered in specifying the right system for a home. In addition to the current radon level, you will need to provide us with some information specific to your house. When you contact us for a radon system quote, the sales representative will ask you the size and age of the house, details about the foundation (basement or slab, concrete block, poured cement, or stone construction) and whether you have a sump pit, French drain, or exposed-soil crawl space. You will also be asked about any additions to the original structure. In most cases, this information will allow us to make an accurate assessment of your radon mitigation needs and give you an accurate quote on the appropriate system over the phone. However, our experienced sales staff can recognize when a home requires an on site assessment, and will recommend a technician make a pre-mitigation site visit in these cases. In all cases, the technician will make an onsite inspection prior to beginning a radon system installation.

How do I know if my radon system is functioning properly?

Each system is equipped with a u-tube manometer. This instrument indicates that the fan is creating adequate pressure for the system to function adequately. It is a simple way to visually confirm that your system is working normally. You will also be provided with a do-it-yourself radon test kit which will allow you to confirm that your radon levels have decreased. We recommend that homeowners wait at least one week before conducting the test to allow time for the radon levels to drop.

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