There is no scientific doubt that Radon gas is a known human lung carcinogen. Prolonged exposure to high levels of Radon gas can cause lung cancer. Millions of homes and buildings contain high levels of radon gas. EPA^s efforts are directed at locating the homes with high levels and encouraging remediation of them.
As a means of prevention, EPA and the Office of the Surgeon General recommend that all homes below the third floor be tested for Radon. Because Radon is invisible and odorless, a simple test is the only way to determine if a home has high radon levels. EPA recommends mitigating homes with high Radon levels and there are straight-forward reduction techniques that will work in virtually any home.
Most homes won^t have a Radon problem, but there is a simple test to find out if you do or don^t have high Radon levels in your home.
Sources of Radon: Earth and rock beneath home; well water; building materials.
Health Effects From Exposure to Radon: No immediate symptoms. Estimated to contribute to between 7,000 and 30,000 lung cancer deaths each year. Smokers are at higher risk of developing Radon-induced lung cancer.
Radon Levels in Homes: Based on a national residential radon survey completed in 1991, the average indoor radon level is 1.3 picocuries per liter (pCi/L) in the United States. The average outdoor level is about 0.4 pCi/L.
In 1998, the National Academy of Sciences (NAS) released the Biological Effects of Ionizing Radiation (BEIR VI) Report, "The Health Effects of Exposure to Indoor Radon." The study reviewed and evaluated data from many prior studies and drew conclusions. It fully supports estimates by EPA that radon causes about 15,000 lung cancer deaths per year. Though some people debate the number of deaths, it is widely agreed that radon exposure is the second leading cause of lung cancer.
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 in 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
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.
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, 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. EPA generally recommends methods that prevent the entry of radon.
In many cases, 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 remove radon gas from below the concrete floor and the foundation before it can enter the 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 your contractor choose the best system. Your contractor will perform a visual inspection of your house and design a system that is suitable. If this inspection fails to provide enough information, the contractor will need to perform diagnostic tests to help develop the best radon reduction system for your home. Whether diagnostic tests are needed is decided by details specific to your house, such as the foundation design, what kind of material is under your house, and by the contractor^s experience with similar houses and similar radon test results.