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Radon - What Is A Safe Level?


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Radon is a naturally occurring radioactive gas that can cause lung cancer.   You can’t see or smell radon. Testing is the only way to know your level of exposure.  Radon can have a big impact on indoor air quality.


Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas. It occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead; radon, itself, is a decay product of radium. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Since thorium and uranium are two of the most common radioactive elements on Earth, and since their isotopes have very long half-lives, on the order of billions of years, radon will be present long into the future.

Unlike all the other intermediate elements in the aforementioned decay chains, radon is, under normal conditions, gaseous and easily inhaled. Radon gas is a health hazard. It is often the single largest contributor to an individual's background radiation dose, but due to local differences in geology, the level of the radon-gas hazard differs from location to location. Despite its short lifetime, radon gas from natural sources can accumulate in buildings, especially, due to its high density, in low areas such as basements and crawl spaces. Radon can also occur in ground water - for example, in some spring waters and hot springs.

Epidemiological studies have shown a clear link between breathing high concentrations of radon and incidence of lung cancer. Radon is a contaminant that affects indoor air quality worldwide. According to the United States Environmental Protection Agency (EPA), radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States. About 2,900 of these deaths occur among people who have never smoked. While radon is the second most frequent cause of lung cancer, it is the number one cause among non-smokers, according to EPA estimates.  As radon itself decays, it produces other radioactive elements called radon progeny (also known as radon daughters) or decay products. Unlike the gaseous radon itself, radon daughters are solids and stick to surfaces, such as dust particles in the air. If such contaminated dust is inhaled, these particles can also cause lung cancer.   (Source:Wikipedia)

How Radon enters a houseEPA Guides to Radon Safety

The EPA has an informative online document: "Radon - A Physician's Guide: The Health Threat With A Simple Solution", that was published a while back and has a lot of introductory and tutorial information about radon, it's health risk, how to avoid problems and correct them if they are encountered, and what is a safe level (the short answer: There is no "safe" level.)




See also:

Radon and Real Estate
Home Buyers and Seller's Guide to Radon

Residential Air Cleaning Devices: A Summary of Available Information
EPA Map of Radon Zones


Radon is deadlier than...

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EPA: Consumer's Guides to Radon Reduction

The EPA's web site has a section dedicated to Indoor Air Quality, including information about radon and it's hazards. They have several good online publications (in PDF format) about understanding radon and reducing radon in the home (for example, "Consumer’s Guide to Radon Reduction How to Fix Your Home 2016" and "A Citizen’s Guide to Radon The Guide to Protecting Yourself and Your Family from Radon").

For a list of available publications, click/tap on the following link and enter your search text:


See also:  Home Buyers and Seller's Guide to Radon


EPA: Local Radon Zones and State Contact Information

Find Information about Local Radon Zones and State Contact Information
Map: EPA Radon Zones (with State Information)

EPA Map of South Carolina Radon Zones at County Level  [PDF]     [Alternate Link]

Map of Radon Zones in South Carolina

Note: Greenville County area is in the red Zone 1.


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