Frequently Ask Questions
Where does radon come from?
Radon comes from the natural radioactive decay of radium and uranium found in the soil beneath the house. The amount of radon in the soil depends on soil chemistry, which varies from one house to the next. Radon levels in the soil range from a few to a few thousands of pCi/L. The amount of radon that escapes from the soil to enter the house depends on the weather, soil porosity, soil moisture, and the suction within the house.
How does radon get into the house?
Houses act like large chimneys. As the air in the house warms, it rises to leak out the attic openings and around the upper floor windows. This creates a small suction at the lowest level of the house, pulling the radon out of the soil and into the house. You can test this on a cold day by opening a top floor window an inch. You will notice warm air from the house rushing out that opening; yet, if you open a basement window an inch, you will feel the cold outside air rushing in. This suction is what pulls the radon out of the soil and into the house.
You might think caulking the cracks and the openings in the basement floor will stop the radon from entering the house. It is unlikely that caulking the accessible cracks and joints will permanently seal the openings radon needs to enter the house. The radon levels will still likely remain unchanged.
Fortunately, there are other extremely effective means of keeping radon out of your home. Throughout the country, several million people have already tested for radon. Some houses tested as high as 2,000-3,000 pCi/L; yet, there hasn't been one house that could not mitigate to an acceptable level.
What is the risk of radon exposure?
Scientists believe radon exposure is the second leading cause of lung cancer. When radon decays, it shoots off alpha particles. These are small, heavy, electrically charged, sub-atomic particles consisting of two protons and two neutrons. If an alpha particle strikes the chromosomes in a lung cell, it could alter the way that cell reproduces. Our body's immune system should recognize and destroy these mutant cells before they can multiply over the next 10 to 20 years into a recognizable cancerous growth.
Some people's immune systems are better than others. Because of these inherent differences, radon doesn't affect everyone the same.
How serious a risk is radon?
According to the EPA radon risk chart, radon is a serious health problem causing an estimated 21,000 deaths each year.
Do scientists agree that radon is dangerous to breathe?
There is little disagreement that breathing the hundreds of pCi/L of radon that caused thousands of uranium miners to get fatal lung cancer is definitely harmful. Many scientists disagree with the EPA about what the level of radon should be before it should be reduced.
The EPA studied the lung cancer risk of uranium miners exposed to 400 pCi/L. They assume the risk of a homeowner exposed to 4 pCi/L to be one hundredth as much. Based on this assumption, the EPA guideline level of 4 pCi/L represents a much greater risk than allowed for other environmental pollutants.
What factors should I look at in deciding whether to mitigate or not?
Cigarette smokers should keep their exposure to radon as low as possible. Smokers have eight times the risk from radon as non-smokers. If the house was tested in an infrequently used basement, it may have measured a radon level that is higher than the actual level you are exposed to, spending most of your time upstairs.
People with young children should be more concerned with the possible consequences of radon exposure 20 years from now than someone in their late sixties or seventies.
Families with a hereditary predisposition of cancer should be more concerned about radon exposure than families who don't have any history of cancer.
What is the general procedure for testing a home for radon?
Two standard methods exist for testing a home for the presence of radon gas:
* Short-term testing methods are designed to provide a quick radon value. Short-term tests can be as short as 48 hours and as long as 90 days.
* Long-term testing methods are designed to provide an annual average of radon gas. Long-term tests run for a minimum of 91 days, and usually for 6 to 12 months.
The EPA recommends performing a short-term test for radon. If that test comes back below the EPA Action Level ( 4.0 pCi/L), then no further immediate action is warranted. However, the home should be tested again after any air sealing work, heating/air conditioning system changes or foundation modifications. If the short-term test returns with a radon value of 4.0-10.0 pCi/L, the EPA recommends performing a long-term test to gauge the home's annual radon concentration. The results of the long-term test should be used to determine the necessity of radon mitigation (reduction).
Another option is to conduct a second short term test if quicker results are desired. If the first short-term test returns above 10.0 pCi/L, then the EPA recommends performing a second short-term test to verify the results and using the average of the two short-term tests to determine the necessity of radon mitigation.
How is radon removed from homes?
The primary method of radon reduction (mitigation) involves the installation of an Active Soil Depressurization (ASD) system.
An ASD system involves the installation of a venting system that removes radon gas from the soil beneath a house's foundation. The system includes a 3 to 4-inch PVC vent pipe, a continuously running suction fan and a system indicator.
The PVC vent pipe is installed through the foundation into a small pit that is dug out by hand through the insertion hole (which often has to be drilled out). The pipe is then routed either up through the house and exited through the attic and the roof or routed to the exterior of the house and up the wall with the terminus above the eave line of the house. If the vent pipe is routed through the house, the suction fan is usually installed in the attic. If the vent pipe is routed up the outside of the house, the fan is mounted near ground level.
The system indicator is mounted at some visible location below the suction fan. Most systems use a simple U-tube manometer to indicate that suction is being exerted in the pipe by the suction fan.
ASD systems can be adapted for use with all foundation types (basement, slab-on-grade, crawl space, or mixed foundation types) and is the most cost-effective and most efficient means of reducing elevated indoor radon.
What about radon in well water?
Underground well water can transport the radon from the soil into the house, when taking a shower, doing laundry, or washing dishes. The EPA says it takes about 10,000 pCi/L of radon in water to contribute 1.0 pCi/L of radon in air throughout the house.
A1 Healthy Homes recommends home owners using well water have a water test performed to check for high levels of radon.
What about radon in city water?
If your water comes from a municipal reservoir supply, you need not worry about radon in the water. When radon in water is stored in a reservoir for more than 30 days, the radon decays away to practically nothing. Every 3.825 days half the radon disappears through natural radioactive decay.
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