DEFINITION
Radon:
Radon is a gaseous radioactive element having the symbol Rn, the atomic number 86, an atomic weight of 222, a melting point of -71ºC, a boiling point of -62ºC, and (depending on the source, there are between 20 and 25 isotopes of radon - 20 cited in the chemical summary, 25 listed in the table of isotopes); it is an extremely toxic, colorless gas; it can be condensed to a transparent liquid and to an opaque, glowing solid; it is derived from the radioactive decay of radium and is used in cancer treatment, as a tracer in leak detection, and in radiography. (From the word radium, the substance from which it is derived.)
Sources: Condensed Chemical Dictionary, and Handbook of Chemistry and Physics, 69th ed., CRC Press, Boca Raton, FL, 1988.
The Basics
(The following information was found on the U.S. EPA Website -
www.epa.gov)
What is radon?
Radon (chemical symbol Rn) is a naturally occurring radioactive
gas found in soils, rock, and water throughout the U.S. It has
numerous different isotopes, but radon-220, and -222 are the most
common. Radon causes lung cancer, and is a threat to health because
it tends to collect in homes, sometimes to very high concentrations.
As a result, radon is the largest source of exposure to naturally
occurring radiation.
Who discovered radon?
The German chemist Friedrich E. Dorn discovered radon-222 in
1900, and called it radium emanation. However, a scarcer isotope,
radon-220, was actually observed first, in 1899, by British scientists
R.B. Owens and Ernest Rutherford. The medical community nationwide
became aware of radon in 1984 That year a nuclear plant worker
in Pennsylvania discovered radioactivity on his clothing while
exiting his place of work through the radiation detectors. The
source of the radiation was determined to be radon decay products
on his clothing originating from his home.
Where does radon come from?
Radon-222 is the decay product of radium-226. Radon-222 and its
parent, radium-226, are part of the long decay chain for uranium-238.
Since uranium is essentially ubiquitous in the earth's crust,
radium-226 and radon-222 are present in almost all rock, soil,
and water.
What are the properties of radon?
Radon is a noble gas, which means it is essentially inert, and
does not combine with other chemicals. Radon is a heavy gas, which
accounts for its tendency to collect in basements. It has no color,
odor, or taste. Radon-222 is produced by the decay of radium,
has a half-life of 3.8 days, and emits an alpha particle as it
decays to polonium-218, and eventually to stable lead. Radon-220,
is the decay product of thorium – it is sometimes called
thoron, has a half-life of 54.5 seconds and emits an alpha particle
in its decay to polonium-216.
Does radon have any practical uses?
Radon has little practical use. Some medical treatments have
employed radon in small sealed glass tubes, called seeds, that
are specially manufactured to contain the exact amount of radioactivity
needed for the application.
Radon (chemical symbol Rn) is a naturally occurring radioactive gas found in soils, rock, and water throughout the U.S. It has numerous different isotopes, but radon-220, and -222 are the most common. Radon causes lung cancer, and is a threat to health because it tends to collect in homes, sometimes to very high concentrations. As a result, radon is the largest source of exposure to naturally occurring radiation.
The German chemist Friedrich E. Dorn discovered radon-222 in 1900, and called it radium emanation. However, a scarcer isotope, radon-220, was actually observed first, in 1899, by British scientists R.B. Owens and Ernest Rutherford. The medical community nationwide became aware of radon in 1984 That year a nuclear plant worker in Pennsylvania discovered radioactivity on his clothing while exiting his place of work through the radiation detectors. The source of the radiation was determined to be radon decay products on his clothing originating from his home.
Radon-222 is the decay product of radium-226. Radon-222 and its parent, radium-226, are part of the long decay chain for uranium-238. Since uranium is essentially ubiquitous in the earth's crust, radium-226 and radon-222 are present in almost all rock, soil, and water.
Radon is a noble gas, which means it is essentially inert, and does not combine with other chemicals. Radon is a heavy gas, which accounts for its tendency to collect in basements. It has no color, odor, or taste. Radon-222 is produced by the decay of radium, has a half-life of 3.8 days, and emits an alpha particle as it decays to polonium-218, and eventually to stable lead. Radon-220, is the decay product of thorium – it is sometimes called thoron, has a half-life of 54.5 seconds and emits an alpha particle in its decay to polonium-216.
Radon has little practical use. Some medical treatments have employed radon in small sealed glass tubes, called seeds, that are specially manufactured to contain the exact amount of radioactivity needed for the application.
CONNECTICUT
The U.S. EPA and the U.S. Geological Survey have evaluated the radon potential in the U.S. and have developed this map is to assist National, State, and local organizations to target their resources and to assist building code officials in deciding whether radon-resistant features are applicable in new construction. This map is not intended to be used to determine if a home in a given zone should be tested for radon. Homes with elevated levels of radon have been found in all three zones. All homes should be tested regardless of geographic location. The map assigns each of the 3,141 counties in the U.S. to one of three zones based on radon potential. Each zone designation reflects the average short-term radon measurement that can be expected to be measured in a building without the implementation of radon control methods. The radon zone designation of the highest priority is Zone 1.
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Zone 1 | Highest Potential (greater than 4 pCi/L) |
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Zone 2 | Moderate Potential (from 2 to 4 pCi/L) |
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Zone 3 | Low Potential (less than 2 pCi/L) |
Important: Consult the EPA Map of Radon Zones document (EPA-402-R-93-071) before using this map. This document contains information on radon potential variations within counties. EPA also recommends that this map be supplemented with any available local data in order to further understand and predict the radon potential of a specific area. This and other indoor air quality publications can be ordered through the IAQ INFO Clearinghouse.
IAQ INFO
P.O. Box 37133, Washington, DC 20013-7133
1-800-438-4318/703-356-4020
(fax) 703-356-5386
iaqinfo@aol.comor, you can order publications directly via EPA's National Service Center for Environmental Publications (NSCEP) (http://www.epa.gov/ncepihom/). web site. Your publication requests can also be mailed, called or faxed directly to:
U.S. Environmental Protection Agency
National Center for Environmental Publications (NSCEP)
P.O. Box 42419
Cincinnati, OH 42419
1-800-490-9198/(513) 489-8695 (fax)
Please use the EPA Document Number (EPA-402-R-93-071) and specify which state you wish to have a profile, when ordering from NSCEP or from IAQ INFO.
