Skip to main content
Radon Mitigation | Radon Testing | Radon Remediation & Reduction | Air Quality ControlRadon LinksStudies Exposure-Effect|Lung Cancer Risk Research Study|Evidence Proof of Health ImpactHow To Install Radon Mitigation SystemTestimonialsRadon Mitigation Article 2011: Radon RemediationWater SystemsLocations
 Radon Blog 
Tuesday, March 09 2010
Radon Remediation / Radon Mitigation:  When a building (or house) is found to have an elevated level of radon gas (defined by the U.S. Environmental Protection Agency as a radon result of 4.0 pCi/l or higher,) methods of reducing the radon levels can be applied to cure the problem.  The most common method of radon mitigation (also known as radon remediation or radon gas abatement) is Active Soil Depressurization (ASD.) An ASD Radon Mitigation System utilizes PVC piping attached to an electric radon suction fan.  The piping typically begins below the lowest floor of the structure's foundation (penetrating the slab of the basement or the plastic membrane of the crawl space) and extends upward to an exit point above ground level.  The inline radon fan is mounted in an inconspicuous location on the exterior or within an attic above the home.  In cases where the radon fan is installed in the attic, the discharge pipe extends out through the roof so the radon gas can be released outdoors.  Once radon is released into the atmosphere, it is no longer hazardous.  Radon is only dangerous when trapped indoors.

Active (fan assisted) radon mitigation systems can reduce the radon gas entry by as much as 99%.  A qualified radon contractor (also known as a radon mitigator or radon remediation specialist) can typically install a radon mitigation system in a home in less than a day.  After the system is installed, the radon levels begin to drop almost immediately.  Passive radon reduction techniques (such as sealing cracks or installing pipes without an inline radon fan) are rarely effective at reducing radon levels.  The reason that these "passive" radon reduction techniques are ineffective is because radon gas is under pressure and must escape from the ground.  It is a very inert, un-reactive gas that can be drawn up through the pours of concrete, around drains, utility penetrations, or expansion joints.  Attempting to "seal out" radon is similar to trying to keep water out of a basement by painting the walls and floor with waterproofing paint.  It may work temporarily if the problem is minor, but it wouldn't keep standing water out.  The only way to fix a water problem is to redirect the water somewhere else before it enters the home.  The same principles apply to radon correction.  Sealing cracks and openings is part of the radon mitigation process; however this is to prevent the downward draw of conditioned air from the home and to improve the pressure field extension of the system below the slab, not to "seal out" the radon.

Radon is a colorless, odorless, naturally occurring, radioactive noble gas that is formed from the decay of radium. Radon gas is one of the heaviest substances that remains a gas under normal conditions and is considered to be a health hazard. The most stable isotope, Rn222 (Radon Gas), has a half-life of 3.8 days and is used in radiotherapy. While having been less studied by chemists due to its radioactivity, there are a few known compounds of this generally un-reactive element.

Radon is a significant contaminant that affects indoor air quality worldwide. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as the basement. Radon can be found in some spring waters and hot springs.

According to the United States Environmental Protection Agency, radon is reportedly the second most frequent cause of lung cancer, after cigarette smoking; and radon-induced lung cancer the 6th leading cause of cancer death overall. According to the same sources, radon reportedly causes 21,000 lung cancer deaths per year in the United States.  Because of this, radon mitigation systems can be life-savers.

Indoor radon can be mitigated by sealing basement foundations, water drainage, or by sub-slab de-pressurization. In severe cases, radon mitigation can be achieved via air pipes and fans to exhaust sub-slab air to the outside. Indoor radon ventilation systems are less visible, but exterior radon systems can be more cost-effective in some cases. Modern construction that conserves energy by making homes air tight exacerbates the risks of radon exposure if radon is present in the home. Older homes with more porous construction are more likely to vent radon naturally. Ventilation systems can be combined with a heat exchanger to recover energy in the process of exchanging air with the outside.  (This is more common with commercial and industrial radon mitigation.)   Homes built on a crawl space can benefit from a radon collector installed under a radon barrier (a sheet of plastic that covers the crawl space).

The most common approaches are active soil depressurization (ASD) which utilizes a radon mitigation suction fan to pull the gas out from below the foundation of the home.  The radon fan is attached in-line with a PVC pipe system running from the foundation to the roof of the home.  Once the radon gas is discharged outdoors, it becomes diluted by the outdoor air to levels that are not hazardous.




How Radon Enters Your House

Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil, rock, and water.  Air pressure inside your home is usually lower than pressure in the soil around your home's foundation. Because of this difference in pressure, your house acts like a vacuum, drawing radon in through foundation cracks and other openings. Radon Mitigation works by changing the pressure difference between the soil and the home.  Radon gas may also be present in well water and can be released into the air in your home when water is used for showering and other household uses. In most cases, radon entering the home through water is a small risk compared with radon entering your home from the soil. Systems are available to reduce radon entry from water sources.  In a small number of homes, the building materials (e.g., granite and certain concrete products) can give off radon, although building materials rarely cause radon problems by themselves.  In the United States, radon gas in soils is the principal source of elevated radon levels in homes.

Radon is a Cancer-causing, Radioactive Gas
Radon is estimated to cause many thousands of lung cancer deaths each year. In fact, the Surgeon General has warned that radon is the second leading cause of lung cancer in the United States.  Only smoking causes more lung cancer deaths. If you smoke and your home has high radon levels, your risk of lung cancer is especially high.  If your test shows a level of 2.7 pCi/l or above, consider installing a radon remediation system.

What Do Your Radon Test Results Mean?

Selecting a Radon Test Kit

Before you'll know if you need a radon mitigation system, you need to conduct a test.  Since you cannot see or smell radon, special equipment is needed to detect it. When you're ready to test your home, contact your state radon office (or visit our radon testing page for information on locating qualified test kits or qualified radon testers. You can also order test kits and obtain information from a radon hotline. There are two types of radon testing devices. Passive radon testing devices do not need power to function. These include charcoal canisters, alpha-track detectors, charcoal liquid scintillation devices, and electret ion chamber detectors. Both short- and long-term passive radon devices are generally inexpensive. Active radon testing devices require power to function and usually provide hourly readings and an average result for the test period. These include continuous radon monitors and continuous working level monitors, and these tests may cost more. A state or local official can explain the differences between radon devices and recommend ones which are more appropriate for your needs and expected testing conditions. Make sure to use a radon testing device from a qualified laboratory.

Any radon exposure has some risk of causing lung cancer. The lower the radon level in your home, the lower your family's risk of lung cancer.  A radon mitigation system installed by a qualified (radon certified) contractor could save your life.  The amount of radon in the air is measured in "picocuries of radon per liter of air," or "pCi/L."  Sometimes test results are expressed in Working Levels, "WL," rather than picocuries per liter of air.  A level of 0.016 WL is usually equal to about 4 pCi/L in a typical home.  With this level, a radon abatement system would be recommended.

The U.S. Congress has set a long-term goal that indoor radon levels be no more than outdoor levels.  About 0.4 pCi/L of radon is normally found in the outside air.  EPA recommends fixing your home if the results one long-term test or the average of two short-term tests show radon levels of 4 pCi/L (or 0.016 WL) or higher.  With today's technology, radon levels in most homes can be reduced to 2 pCi/L or below.  You may also want to consider radon mitigation if the level is between 2 and 4 pCi/L.

A short-term radon test remains in your home for 2 days to 90 days, whereas a long-term test remains in your home for more than 90 days.  All radon tests should be taken for a minimum of 48 hours.  A short-term test will yield faster results, but a long-term test will give a better understanding of your home's year-round average radon level and indicate if a radon abatement or mitigation system is necessary.

The EPA recommends two categories of radon testing.  One category is for concerned homeowners or occupants whose house is not for sale; refer to EPA's A Citizen's Guide to Radon for testing guidance.  The second category is for radon testing and reduction in real estate transactions; refer to EPA's Home Buyer's and Seller's Guide to Radon, which provides guidance and answers to some common questions.

Why Hire a Radon Contractor?

EPA recommends that you have a qualified radon mitigation contractor fix your home because lowering high radon levels requires specific technical knowledge and special skills. Without the proper equipment or technical knowledge, you could actually increase your radon level or create other potential hazards and additional costs. However, if you decide to do the work yourself, get information on appropriate training courses and copies of EPA's technical guidance radon documents.

Will Any Radon Company Do?

EPA recommends that you use a state certified and/or qualified radon mitigation contractor trained to fix radon problems. You can determine a service provider's qualifications to perform radon measurements or to mitigate radon from your home in several ways.  First, check with your state radon office.  Many states require radon professionals to be licensed, certified, or registered, and to install radon mitigation systems or conduct radon testing.  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, and if they follow industry consensus standards such as the American Society for Testing and Materials (ASTM) Standard Practice for Installing Radon Mitigation Systems in Existing Low-Rise Residential Buildings, E2121 (February 2003).  You can contact private proficiency programs for lists of privately-certified professionals in your area.  Such programs usually provide members with a photo-ID, which indicates their qualification(s) and the ID-card's expiration date.  For more information on private proficiency programs or contact your state radon office.

How To Select A Radon Mitigator

Get Estimates

Choose a radon contractor to fix the problem just as you would choose someone to do other home repairs. It is wise to get more than one estimate, to ask for references, and to contact some of those references to ask if they are satisfied with the radon mitigation company's work. Also, ask your state radon office or your county/state consumer protection office for information about the radon companies.

Use this check-list when evaluating and comparing radon contractors and ask the following questions:






Will the contractor provide references or photographs, as well as test results of 'before' and 'after' radon levels of past radon reduction work?


Can the contractor explain what the work will involve, how long it will take to complete, and exactly how the radon mitigation system will work?


Does the contractor charge a fee for any diagnostic tests? Although many contractors give free estimates, they may charge for diagnostic tests.  These tests help determine what type of radon reduction system should be used and in some cases are necessary, especially if the contractor is unfamiliar with the type of house structure or the anticipated degree of difficulty.  See "Radon Reduction Techniques" for more on diagnostic tests.


Did the contractor inspect your home's structure before giving you an estimate for radon mitigation?


Did the contractor review the quality of your radon measurement results and determine if appropriate testing procedures were followed?

Compare the contractors' proposed costs for the radon system and consider what you will get for your money, taking into account: (1) a less expensive system may cost more to operate and maintain; (2) a less expensive system may have less aesthetic appeal; (3) a more expensive system may be best for your house; and, (4) the quality of the building material will affect how long the radon mitigation system lasts.

Does the radon contractor's proposal and estimate include:






Proof of state certification and/or professional proficiency or radon certification credentials?


Proof of liability insurance and being bonded, and having all necessary licenses to satisfy local radon remediation requirements?


Diagnostic testing prior to design and installation of a radon removal system?


Installation of a warning device to caution you if the radon mitigation system is not working correctly?


Testing after installation to make sure the radon reduction system works well?


A guarantee to reduce radon levels to 4 pCi/L or below, and if so, for how long?

The Radon Abatement Contract

Ask the contractor to prepare a contract before any radon remediation work starts. Carefully read the contract before you sign it. Make sure everything in the contract matches the original proposal. The contract should describe exactly what work will be done prior to and during the installation of the radon system, what the system consists of, and how the system will operate.  Many radon contractors provide a guarantee that they will adjust or modify the system to reach a negotiated radon level.  Carefully read the conditions of the contract describing the guarantee.  Carefully consider optional additions to your contract which may add to the initial cost of the radon removal system, but may be worth the extra expense. Typical options might include an extended warranty, a service plan, and/or improved aesthetics.




 Important information that should appear in the radon abatement system contract includes:

The total cost of the job, including all taxes and permit fees; how much, if any, is required for a deposit; and when payment is due in full.

The time needed to complete the radon removal work.

An agreement by the contractor to obtain necessary permits and follow required building codes for radon mitigation.

A statement that the contractor carries liability insurance and is bonded and insured to protect you in case of injury to persons, or damage to property, while the radon work is done.

A guarantee that the contractor will be responsible for damage and clean-up after the job.

Details of any guarantee to reduce radon below a negotiated level.

Details of warranties or other optional features associated with the hardware components of the mitigation system.

A declaration stating whether any warranties or guarantees for the radon remediation work are transferable if you sell your home.

A description of what the contractor expects the homeowner to do (e.g., make the work area accessible) before work begins.

What to Look for in a Radon Reduction System

In selecting a radon reduction method for your home, you and your contractor should consider several things, including: how high your initial radon level is, the costs of installation and system operation, your house size and your foundation type.

Installation and Operating Costs of Radon Ventilation Equipment

Most types of radon reduction systems cause some loss of heated or air conditioned air, which could increase your utility bills. How much your utility bills will increase will depend on the climate you live in, what kind of reduction system you select, and how your house is built. Systems that use fans are more effective in reducing radon levels; however, they will slightly increase your electric bill. The "Installation and Operating Cost Table" lists the installation and average operating costs for different radon reduction systems and describes the best use of each method.




Posted by: Radon Mitigation Systems AT 03:29 am   |  Permalink   |  Email