Environment Magazine

Radon Gas- the Major Threat of Indoor Air Pollution.

Posted on the 25 December 2019 by Priyadarshi @priyadarshi64

Radon is the most important cause of lung cancer after smoking.

ByDr. Nitish Priyadarshi. Geologistemail: [email protected]
Radon gas- the major threat of indoor air pollution.

Radon is a naturally occurring radioactive gas which may be found in indoor environments such as homes, schools, and workplaces. Radon is the most important cause of lung cancer after smoking. All types of houses can have radon problems-old homes, new homes, drafty homes, insulated homes, homes with basements and homes without basements. Construction materials and the way the home has been built may also affect radon levels, but this is rare.A radon level of 4 picoCuries per liter (pCi/L) or more is considered high.

Radon is a gas produced by the radioactive decay of the element radium. Radioactive decay is a natural, spontaneous process in which an atom of one element decays or breaks down to form another element by losing atomic particles (protons, neutrons, or electrons). When solid radium decays to form radon gas, it loses two protons and two neutrons. These two protons and two neutrons are called an alpha particle, which is a type of radiation. The elements that produce radiation are called radioactive. Radon itself is radioactive because it also decays, losing an alpha particle and forming the element polonium.

Elements that are naturally radioactive include uranium, thorium, carbon, and potassium, as well as radon and radium. Uranium is the first element in a long series of decay that produces radium and radon. Uranium is referred to as the parent element, and radium and radon are called daughters. Radium and radon also form daughter elements as they decay.

The decay of each radioactive element occurs at a very specific rate. How fast an element decays is measured in terms of the element "half-life", or the amount of time for one half of a given amount of the element to decay. Uranium has a half-life of 4.4 billion years, so a 4.4-billion-year-old rock has only half of the uranium with which it started. The half-life of radon is only 3.8 days. If a jar was filled with radon, in 3.8 days only half of the radon would be left. But the newly made daughter products of radon would also be in the jar, including polonium, bismuth, and lead . Polonium   is also radioactive - it is this element, which is produced by radon in the air and in people's lungs, that can hurt lung tissue and cause lung cancer.For most people, the greatest exposure to radon occurs in the home. The concentration of radon in a home depends on:

  • the amount of uranium in the underlying rocks and soils;
  • the routes available for the passage of radon from the soil into the home; and
  • the rate of exchange between indoor and outdoor air, which depends on the construction of the house, the ventilation habits of the inhabitants, and the air-tightness of the building.

Radon 222-a naturally occurring radioactive gas that you cannot see, taste or smell- is produced by the radioactive decay of Uranium-238. The other definition is “Radon is a naturally occurring radioactive gas emitted as a result of the radioactive decay of radium 226 (which is an indirect decay product  of uranium)” .  Most soil and rock contain small amounts of uranium -238. But this isotope is much more concentrated in underground deposits of minerals such as uranium, phosphate, granite, and shale. Radon is found in many types of rocks and soils. Although some rocks and soils contain more uranium (and thus greater radon gas potential) than others, all rocks and soil contain at least trace amount of uranium. According to a report, there are 2.7 pounds of uranium for each 1 million pounds of rock.  Granite, however, contains approximately 4.7 pounds of uranium per 1 million pounds, and back shale contains approximately 3.7 pounds of uranium per 1 million pounds. Sandstone contain 0.5 pounds and basalt contains 0.9 pounds per 1 million pounds. Thus, areas with high granite content and black shale, are more likely to have radon gas. When radon gas from such deposits seeps upward through the soil and is released outdoors, it disperses quickly in the atmosphere and decay to harmless levels.   However, radon gas can enter buildings above such deposits through cracks in foundations and walls, opening around sump pumps and drains, and hollow concrete blocks. Once inside , it can build  up to high levels, especially in unventilated lower levels of homes and buildings. Although some radiation is emitted from the building materials themselves, such as bricks. In addition, because the air pressure inside a house is generally lower than the pressure of the soil around the foundation ( because of appliances that use air,  such as furnaces), the structure acts like a Vacuum, drawing the radon in from the soil. Radon may also be present in groundwater and can be release into the air through faucets and shower heads.In the open air, radon generally is diluted into insignificant concentrations. However, when radon is trapped and allowed to concentrate, such as within a building, it presents a serious health threat to the inhabitants. In many countries, drinking water is obtained from groundwater sources such as springs, wells and boreholes. These sources of water normally have higher concentrations of radon than surface water from reservoirs, rivers or lakes.Effects of RadonRadon -222 gas quickly decays into solid particles of other radioactive elements that, if inhaled, expose lung tissue to a large amount of ionizing radiation from alpha particle. When inhaled, the decay of the radon releases solid radioactive particles ( polonium). Although the half life of polonium is only a few minutes, while it is within the lungs, it continues to decay, which releases ionizing alpha radiation. This exposure can damage lung tissue and lead to lung cancer over the course of  a 70 year lifetime. Your chances of getting lung cancer from radon depend mostly on how much radon is in your home, how much time you spend in your home, and whether  you are a smoker or have ever smoked. In 1998, the National Academy of Sciences estimated that prolonged exposure for a life time of 70 years to low levels of radon or radon acting together with smoking is responsible for 15,000-22,000 ( or 12%) of the lung cancer deaths each year in the United States. This makes the radon the second leading cause of lung cancer after smoking.
What are the symptoms of radon in your home?       persistent cough.  ·   coughing up blood.·   wheezing.·   shortness of breath.·   hoarseness.·   chest pain, especially when you cough or laugh.·   frequent infections such as bronchitis and pneumonia.


Radon can be controlled in a number of ways, with the control action depending on the level of radon. The primary control actions are to prevent radon from entering the home by either blocking off or sealing potential entry points or to reduce the amount by increasing ventilation. Sealing or blocking radon entry points may require covering exposed earth in basements, storage areas, drains, and crawlspaces with impermeable materials, such as plastic sheeting pr metal. Cracks and openings can be sealed with mortar or caulking. Household ventilation, which can push radon out instead of pulling it inside the home, can be increased with strategically placed fans. In addition, by altering the air pressure inside the home, the vacuum effect can be reduced. This can be accomplished by switching the air  source of certain appliances, such as furnaces and clothes dryers, from inside to outside the home.


Miller, G. Tyler Jr. 2004. Environmental Science. Thomson Learning, USA. Wagner, T. 1994. In our backyard. John Wiley & Sons, INC, New York.


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