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General Questions
Testing Air for Radon
Radon Resistant Construction
Mitigating Radon Problems
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 the 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 3.8 days - half of a given quantity of it breaks down every 3.8 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.
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 and second only to smoking. If you smoke and you are exposed to elevated radon levels, your risk of lung cancer is considerably higher. 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. The EPA estimates that radon causes about 14,000 - 30,000 lung cancer deaths per year. It is widely agreed that radon exposure is most definitely the second leading cause of lung cancer.
What is the "acceptable" level of radon in air?
EPA states that any radon exposure carries some risk and 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, EPA's recommended action level), there will be approximately 12,672 radioactive disintegrations in one liter of air during a 24-hour period.
How often is indoor radon a problem?
Nearly one out of every 15 homes has a radon level 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 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. 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. The average indoor level of radon is 1.3 pCi/L and the average outdoor level of radon is 0.4 pCi/L..
While radon problems may be more common in some geographic areas, any home may have an elevated radon level. The state of Illinois tends to have higher levels of radon. 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.
Testing Air for Radon
Why should I test my home for radon?
Because radon is widely believed to be the second leading cause of lung cancer. The EPA and the Surgeon General recommend testing for radon in all homes the lowest occupied space. Real estate transactions require testing in the lowest livable space. Radon has been found in homes all over the United States and knows no boundaries. Any home can have a radon problem. On average, one out of every fifteen homes in the United States has a problem and the only way to know whether you have it in your home or not is to have a licensed professional test for it.
If a test result is less than 4 pCi/L what should be done next?
If the result of an initial test measurement is below 4 pCi/L, a follow-up test is not necessary. Because radon levels can change over time, you will want to retest every couple of years, especially if use patterns change or perhaps a lower level of the building becomes occupied or used more frequently. Renovations, changes in ventilation, earthquakes, settling of the ground beneath the building, and other changes may cause indoor radon levels to change.
If a test result is 4 pCi/L or higher, what should be done next?
The EPA has stated that in order for a home to be deemed safe, the radon levels should not exceed 4 pCi/L. You may want to consider a follow-up test should your test results come back slightly elevated in order to confirm whether radon levels are high enough to warrant mitigation. If the average of the initial test and the second test results are equal to or greater than 4 pCi/L, then radon mitigation is highly recommended. If the average of the two test results are less than 4 pCi/L, consider testing again sometime in the future. Additionally, because radon levels can fluctuate between seasons or during varying weather conditions by a considerable amount, a retest following the initial test may be warranted.
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.
The method that we at Radon Rescue use to lower radon levels in your home actually prevents radon from entering your home and the EPA generally recommends that method. Such systems are called "sub-slab depressurization," and do not require major changes to your home. These systems change the pressure dynamics of your home by circumventing the mechanics that bring radon into your home. Similar systems can also be installed in houses with crawl spaces. The right system depends on the design of your home and other factors.
Supplying us with any information that you may have about the construction of your home would most certainly help us determine the best system for you
Radon Resistant Construction
What are radon-resistant features?
The techniques vary for different foundations and site requirements, but the basic elements are:
- 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.
- 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.
- Sealing and Caulking - All openings in the concrete foundation floor are sealed to reduce soil gas entry into the home.
- 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.
- Junction Box - An electrical junction box is installed in case an electric venting fan is needed later.
Ways to reduce radon in your home are discussed in EPA's publication, Consumer's Guide to Radon Reduction.
When should radon-resistant construction be considered?
Find out if you are buying a home in a high radon area. 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. You can contact your state radon office to learn whether radon-resistant features are recommended or required in your area.
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 and mold problems. They make a home more energy efficient, and can save 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 $600 (a 128% to 400% saving).
Should a home built with radon-resistant features be tested?
Yes. Every new home should be tested for radon after occupancy. Have your home tested by a Licensed Radon Professional even if it has the radon resistant features. Also, it is recommended that your home be tested every 2 years.
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, the 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.
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 change the pressure dynamics of your home by circumventing the mechanics that bring radon into your 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. 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 us choose the best system. We will select a system that is suitable for your home.
Will any more testing be needed after a radon mitigation system has been installed?
Your home should be tested after a mitigation system has been installed to insure 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). To avoid conflict of interest hire an independent tester to do the post mitigation test. In addition, it is wise to retest your home every two years to insure radon levels remain low. Retesting is also recommended if the building undergoes significant alteration. |
