What is Radon?
Radon is an odorless, colorless, tasteless, radioactive gas that is naturally present in our atmosphere. It is a byproduct of disintegrating rock in the ground.
As the rock splits and crumbles, it releases radon into the air. The radon itself is not the health hazard; rather the hazard is a result of the radioactive gas charging dust particles in the air with gamma radiation. These radioactive particles are then inhaled and can adhere to the lung tissue and release energy that can damage or kill sensitive cells as well as damage DNA molecules and cause lung cancer.
The potential for developing lung cancer is a function of the amount of radon exposure and for how long. Oh, and if a person is a smoker, the risk of getting lung cancer from radon is substantially greater. The Environmental Protection Agency estimates there are 21,000 deaths each year from radon-related lung cancer. Only cigarette smoking results in more lung cancer-related deaths.
Any house can have a radon problem. New houses and older houses, well-sealed and drafty houses, and houses with or without basements may all be subject to elevated radon levels. The EPA estimates that nearly 1-out-of-15 houses in all 50 states will have elevated radon levels. The amount of radon found in the soil can vary greatly within small geographic regions and will depend on the amount of uranium and radium found in the underlying rock structure of soil the house is built on. The amount of radon entering a structure can be affected by the strength of the radon source, underlying soil type, the water content of the soil, and empty spaces in the soil.
Radon is usually only a hazard when it gets concentrated in living areas of a home over long periods.
How Radon Gets Inside the Home
During a natural geologic process, rock in the soil becomes fractured and small amounts of radon get emitted into the air. As the radon seeps out of the soil, it enters the home through its foundation cracks, vent systems, pipe penetrations, plumbing and heat pipe ducts, and unsealed soil areas. Sometimes the gas will also get sucked into the structure because of negative pressure caused by heating systems, fireplaces, and chimneys. This negative pressure happens when warm air of the heating system moves upward, creating a negative pressure in lower areas that causes replacement air to enter. Because radon is a gas that has a heavier molecule than oxygen, it will eventually settle out of the air to the lowest levels of the home when there isn’t enough ventilation to keep it moving to the outdoors.
Water can also be a source of radon – usually not from our municipal water supplies, but from wells where water might travel through rock, or be drilled into bedrock that is releasing radon where the radon becomes trapped in the water and released again when the water gets converted to steam inside the home such as with a hot shower, washing machine, cooking, and other steam-producing uses for the water. Radon levels can actually increase up to 200 times beyond the recommended action level because of released radioactivity during a shower.
How Radon is Measured
Radon is measured in Picocuries per liter. A picocurie is one trillionth of a curie. There is no current agreement among health professionals for a safe level of radon exposure. The EPA has a suggested an indoor "action level" of 4.0 pCi/L. Here are some EPA recommendations for various radon measurement levels inside a home:
Testing for Radon
Although radon levels can be localized, any house could have a high-level radon. For example, two houses located side-by-side can have dramatically different radon levels, and general radon concentrations in a local area or even state should not be relied upon as an indicator for a specific house. The amount of radon in a structure can come down to one piece of radon producing rock in the ground underneath a house.
Radon tests are categorized as either short-term or long term. Short-term testing, or more properly called screening, does not definitively identify long-term radon exposure and is useful in determining the presence of radon, but not any long-term level of radon concentration. This type of screening is the one we most often use for a real estate transaction.
Screening requires the testing device to be placed in the lowest, occupied level of the house for not less than 48 hours. At the end of the screening period, the results will reveal the worst case scenario for radon concentration. Usually, if radon isn’t found in this location, it is not likely to be found elsewhere inside of the house.
Long-term testing involves testing with devices that determine the average exposure to radon over at least three months. Long-term testing is considered definitive and should be employed prior to a mitigation program. Long-term testing should be used to confirm any short-term screening results between 4.0 pCi/liter and 10.0 pCi/liter.
Radon testing devices are further categorized as either active or passive. Passive devices do not require power to function; rather they are exposed to the air in the house for a specified period, and then sent to a laboratory for analysis. These passive devices are inexpensive and cost only about $20 to $35, including the test evaluation fee. The homeowner will want to make sure the testing devices are labeled "EPA listed" or "EPA Approved."
Active devices require power to operate and include continuous radon monitors and continuous working level monitors. These devices continuously measure and record the amount of radon in the air and are capable of detecting unusual swings in reading levels. Many of these devices also provide a report if there is test interference, such as opening a door or window for a long period or being moved from the original location.
These devices are more costly than the passive devices but will provide a more accurate analysis of the radon in a house. These devices also usually require the use of a trained technician and may be used to either conduct short term or long term tests. The short-term tests range from 2 to 90 days. The long-term tests are for periods greater than 90 days.
Tests using active devices will range in price from $75 to $200, depending on the type of device used and the length of the testing period. Most of the active test devices will require the hiring of a trained radon-testing technician. If the test device being used requires the use of a trained technician, the technician should be listed with the EPA's Radon Proficiency Program as a certified technician for the specific device to be used in the test.
Reducing Radon Levels
The logical way to reduce radon levels is to stop it from entering into the structure. However, when this can’t be done, the next thing to do would be to reduce (or to mitigate) it after it enters. Radon reduction techniques usually, but does not always, require a licensed radon mitigation contractor.
The type of foundation of a house generally determines which radon reduction system will work best. For example, slab on grade foundations and homes with basements almost always use suction, while crawl space foundations tend to use ventilation or depressurization techniques.
When radon is found in well water, point-of-use devices, such as those that attach to the faucet are ineffective. Instead, granular activated carbon or aeration methods tend to be the most effective methods for this purpose.
When radon reduction is required, it is important to advise your clients to use professional contractors who have passed the EPA's Radon Contractor Proficiency Program.
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