With the increased awareness of radon in Northern Illinois, I felt this would be a great addition to my site for homeowners to educate themselves with. Radon is very unpredictable. That said, a home in Belvidere could easily have radon, while a home in Poplar Grove would not (and vice versa). In fact, it's so unpredictable that you could have it in your home and your neighbor may not!
What is Radon?
Radon is naturally occurring, odorless, and colorless gas produced by the breakdown of uranium in soil, rock, and water. Because radon is a gas, it can enter buildings through openings or cracks in the foundation. The radon gas itself decays into radioactive solids, called radon daughters. The radon daughters attach to dust particles in the air, and can be inhaled. The inhalation of radon daughters has been linked to lung cancer.
Radon has been identified as the second leading cause of lung cancer in the United States (second only to smoking.) The Environmental Protection Agency reports that radon causes between 15,000 and 22,000 lung cancer deaths every year in the United States.
Every home should be tested for radon regardless of where the home is located, the age of the home, foundation type, or whether or not the home is in an area where homes are “prone to having radon problems.” Homes with elevated radon levels have been found in practically every county in the United States.
The United States Environmental Protection Agency has established that if a home or building is found to have a radon level of 4 pCi/l or higher, action should be taken to reduce it. In most cases, radon levels can be reduced to 2 pCi/l or lower with the installation of an active (fan-assisted) venting system. You can learn more about these systems in the Photos & Diagrams section of this website.
Radon's primary hazard is caused from inhalation of the gas and its highly radioactive heavy metallic decay products (Polonium, Lead, and Bismuth) which tend to collect on dust in the air. The problem arises when these elements stick to the delicate cells lining the passageways leading into the lungs.
There is sufficient evidence for the carcinogenicity of radon and its isotopic forms, radon-222 and radon-220, in experimental animals. When administered by inhalation, preceded by a single exposure to cerium hydroxide dust, radon induced pulmonary adenomas, adenocarcinomas, invasive mixed adenosquamous carcinomas, and squamous cell carcinomas in male rats. Extrapulmonary metastases occurred in only one animal. Most or all of the tumors were believed to be bronchiolar or bronchio-alveolar in origin. Radon decay products in combination with uranium-ore dust induced a progression of activity from single basal cell hyperplasia in bronchioles to malignant tumors in male hamsters when exposed by inhalation. Lung tumors observed were adenomas, adenocarcinomas, and squamous cell carcinomas; bronchiolar and alveolar metaplasia, adenomatous lesions, fibrosis, and interstitial pneumonia were also observed. When administered by inhalation in combination with decay products, uranium-ore dust, and cigarette smoke, radon-induced nasal carcinomas, epidermoid carcinomas, bronchio-alveolar carcinomas, and fibrosarcoma were observed in dogs of both sexes. In general, a significant increase was observed in respiratory tract tumors in rats and dogs in comparison with unexposed animals. A dose- response relationship was noted in those experiments with rats in which radon was tested. In most instances, tumors at sites other than the lung were not reported, but in one study, mention was made of tumors of the upper lip and urinary tract in rats.
An IARC Working Group reported that there is sufficient evidence for the carcinogenicity of radon and its decay products in humans. Increased incidences of lung cancer have been reported from numerous epidemiologic studies of groups occupationally exposed to high doses of radon, especially underground hard rock miners. These include particularly uranium miners, but also groups of iron-ore and other metal miners, and one group of fluorspar miners. Strong evidence for exposure response relationships has been obtained from several studies, in spite of uncertainties that affect estimates of the exposure of the study populations to radon decay products. Several small case-control studies of lung cancer have suggested a higher risk among individuals living in houses known or presumed to have higher levels of radon and its decay products than among individuals with lower presumed exposure in houses. The evidence on the interaction of radon and its decay products with cigarette smoking with regard to lung cancer does not lead to a simple conclusion. The data from the largest study are consistent with a multiplicative or submultiplicative model of synergisms and reject an additive model. In many studies of miners and in one of presumed domestic exposure, small cell cancers accounted for a greater proportion than expected of the lung cancer cases. In one population of uranium miners, this proportion has been declining with the passage of time. Because of the limited scale of epidemiologic studies of nonoccupational exposure to radon decay products available at the time reviews were made, quantification of risk has been based only on data of miners' experience. An IARC Working Group considered that the epidemiologic evidence does not lead to a firm conclusion concerning the interaction between exposure to radon decay products and tobacco smoking. Most of the epidemiologic studies involve small numbers of cases, and the analytical approaches for assessing interaction have been variable and sometimes inadequate.
How Radon is Mitigated
You will never find a level of ZERO in any radon test. Even outdoor air typically has 0.2 to 0.7 pCi/l of radon. However, when a home or building is found to have radon levels that can be considered hazardous, action can be taken to reduce it to acceptable levels. There are several methods that can be used to permanently correct this problem.
The most common approach is what is known as “Active Soil Depressurization” or “ASD.” This method involves drawing the soil gasses (including radon) from the soils that are directly adjacent to the structure. In order for this method to be effective, a sealed barrier between the home and the soil must be available to divert the radon out-gassing away from the home.
In a home with a basement, the concrete slab acts as a barrier between the home and the soil. In this case, a PVC pipe penetrates the slab through an existing opening (such as a sealed-off sump basin) or through a hole in the slab that is created with a coring drill. There is usually a small void between the slab and the soil which allows soil gasses (including radon) to collect, become pressurized, and eventually drawn into the home. Once the radon pipe is inserted into this void area and a suction fan is installed, the radon is drawn into the system and released outdoors. This method is known as sub-slab depressurization and is the most common type of ASD systems.
Other forms of ASD work in a similar manner. For example, homes without basements may use the hollow cavities within the block-wall(s) or drain-tile pipes(s) to collect the radon gas and draw it outside before it can enter the home. Homes with exposed dirt or gravel crawl space areas can be mitigated by the use of a plastic membrane installed over the exposed area. Then the pipe and fan system draw the air (and radon) out from under the plastic membrane and release it outdoors.
99% of all radon problems can be corrected by use of Active Soil Depressurization. This is the preferred method of radon mitigation since it primarily involves extracting air from beneath the home’s foundation (which is the air from soil, or “dirty” air.) Since these systems are designed to avoid the loss of “conditioned” (heated or cooled) air from the home, they have very little impact on the efficiency of the home. There are other advantages to having an ASD system in your home. The systems draw moisture out from under the home before it can enter (like a pre-emptive dehumidifier), and have also been shown to reduce mold spore growth, and eliminate airborne bacteria (which develops in the moist soil beneath the home.
Other methods of reducing radon usually involve exchanging the inside air with outside air. This is known as “dilution.” Although dilution can be an effective way of reducing a home’s radon level, it is not practical because of the cost involved in heating and cooling inside air. Imagine the impact on your heating bill if you left windows open in the wintertime.
The most important thing to realize is that a radon problem can be corrected in any home. A home with a radon mitigation system will consistently have radon levels well below the average American home regardless of how high the radon levels were prior to mitigation.
Click here to view an animation of how Radon is Mitigated.