page_title: Health effects of radon
section_title: Radon testing
hierarchical_section_title: Health effects of radon / Health policies / Radon testing
caption_attribution_description: English: Radon test kit
context_page_description: Radon is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of radium. It is one of the densest substances that remains a gas under normal conditions, and is considered to be a health hazard due to its radioactivity. Its most stable isotope, ²²²Rn, has a half-life of 3.8 days. Due to its high radioactivity, it has been less well-studied by chemists, but a few compounds are known.
  Radon is formed as part of the normal radioactive decay chain of uranium into ²⁰⁶Pb. Uranium has been present since the earth was formed and its most common isotope has a very long half-life, which is the time required for one-half of uranium to break down. Thus, uranium and radon, will continue to occur for millions of years at about the same concentrations as they do now.
  Radon is responsible for the majority of the mean public exposure to ionizing radiation. It is often the single largest contributor to an individual's background radiation dose, and is the most variable from location to location. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as attics, and basements.
context_section_description: There are relatively simple tests for radon gas. Radon test kits are commercially available. The short-term radon test kits used for screening purposes are inexpensive, in many cases free. Discounted test kits can be purchased online through The National Radon Program Services at Kansas State University or through state radon offices. Information about local radon zones and specific state contact information can be accessed through the EPA Map at https://www.epa.gov/radon/find-information-about-local-radon-zones-and-state-contact-information.  The kit includes a collector that the user hangs in the lowest livable floor of the dwelling for 2 to 7 days. Charcoal canisters are another type of short-term radon test, and are designed to be used for 2 to 4 days. The user then sends the collector to a laboratory for analysis. Both devices are passive, meaning that they do not need power to function.
  The accuracy of the residential radon test depends upon the lack of ventilation in the house when the sample is being obtained. Thus, the occupants will be instructed not to open windows, etc., for ventilation during the pendency of test, usually two days or more.
  Long-term kits, taking collections for 3 months up to one year, are also available. An open-land test kit can test radon emissions from the land before construction begins. A Lucas cell is one type of long-term device. A Lucas cell is also an active device, or one that requires power to function. Active devices provide continuous monitoring, and some can report on the variation of radon and interference within the testing period. These tests usually require operation by trained testers and are often more expensive than passive testing. The National Radon Proficiency Program (NRPP) provides a list of radon measurement professionals.
  Radon levels fluctuate naturally. An initial test might not be an accurate assessment of a home's average radon level. Transient weather can affect short term measurements. Therefore, a high result (over 4 pCi/L) justifies repeating the test before undertaking more expensive abatement projects. Measurements between 4 and 10 pCi/L warrant a long-term radon test. Measurements over 10 pCi/L warrant only another short-term test so that abatement measures are not unduly delayed. Purchasers of real estate are advised to delay or decline a purchase if the seller has not successfully abated radon to 4 pCi/L or less.
  Since radon concentrations vary substantially from day to day, single grab-type measurements are generally not very useful, except as a means of identifying a potential problem area, and indicating a need for more sophisticated testing. The EPA recommends that an initial short-term test be performed in a closed building. An initial short-term test of 2 to 90 days allows residents to be informed quickly in case a home contains high levels of radon. Long-term tests provide a better estimate of the average annual radon level.
caption: A radon test kit
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