Radon gas- the major threat of indoor air pollution.

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

By

Dr. Nitish Priyadarshi. 

Geologist

email: nitish.priyadarshi@gmail.com

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 Radon

Radon -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.

Prevention

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.

References:

Miller, G. Tyler Jr. 2004. Environmental Science. Thomson Learning, USA.

Wagner, T. 1994. In our backyard. John Wiley & Sons, INC, New York.

https://www.google.com/search?q=Radon&oq=Radon&aqs=chrome..69i57j0l7.12065j0j7&sourceid=chrome&ie=UTF-8

https://www.who.int/news-room/fact-sheets/detail/radon-and-health

https://www.healthline.com/health/healthy-home-guide/radon-poisoning#reducing-radon

https://water-research.net/index.php/radon

Distribution of Uranium in world coals.

Jharkhand coal contains trace amount of Uranium in North Karanpura coal field.

by

Dr. Nitish Priyadarshi

Coal is largely composed of organic matter, but it is the inorganic matter in coal—minerals and trace elements— that have been cited as possible causes of health, environmental, and technological problems associated with the use of coal. Some trace elements in coal are naturally radioactive. These radioactive elements include uranium (U), thorium (Th), and their numerous decay products, including radium (Ra) and radon (Rn). Although these elements are less chemically toxic than other coal constituents such as arsenic, selenium, or mercury, questions have been raised concerning possible risk from radiation.


Uranium association with coal has a long history. There is a continuing interest in uranium in coal, because it is a source of radioactivity and because it may be an economic source of uranium. It is just 200 years since the discovery of uranium by M.H. Klaproth. The first detection in coal was by Berthoud (1875) who found up to 2% uranium in coal from near Denver, USA. The samples were collected from a mineralized section of the coal-bed. This mine was soon abandoned.

Subsequent field studies have proven several areas with high uranium coals, especially in the United States, mainly in the Dakotas, Wyoming, Montana, Colorado and New Mexico (Vine,1956). It seems that uranium is carried into the coal swamp in solution as carbonate complexes (Breger, et. al. 1955), which then release uranyl ions to form uranyl-organic complexes. In many coals, especially low-U coals, Uranium is predominantly organically bound.

After World War II, a very intensive uranium search was initiated. The measurement of coal radioactivity were performed in many countries; however only a few are documented. For example, in year 1967 scientists have measured uranium concentration in lignites from Spain (Huesca, Lerida, Ternel, Galicia, Murcia) and reported concentration values 20 to 1200 parts per million (ppm).

Gott (1952) has determined uranium distribution in lignites, shales, and limestones from throughout the US, and a possible mechanism for uranium accumulation in lignites was suggested. Highest uranium concentrations were prevalent in lignites from the Dakotas, Wyoming, and Montana (0.01%), and from high ash Nevada lignite which contained up to 0.05 % uranium. It was postulated that uranium was possibly concentrated in lignite by the action of percolating surface waters after having been leached from volcanic ash.

Uranium bearing coal in the Red Desert area in Wyoming has been studied by Masursky; his findings are documented in several reports. In the first report in year 1952, core and channel samples taken from the Red Desert area in Wyoming were used to investigate the origin of uranium in the coal of the region. Specific uraniferous zones examined included the Sourdough, Monument, Battle, and Luman zones. Areas which were topographically higher and in which coal was overlain by conglomerate showed the highest uranium concentration. Studies of core samples revealed that uranium concentration in the coal beds correlates well with the degree of permeability of adjacent rocks. Where coal beds are overlain or underlain by sandstone, the greatest concentrations of uranium occur at the top and / or bottom of the bed.

J.R. Gill and others in the year 1959 have studied uranium bearing lignite in South Dakota and Montana. They have reported some lignite deposits containing as much as 0.1% uranium.

Coal samples were analyzed for uranium concentration in the coals from the Western United States and approximately 300 coals from the Illinois Basin. In the majority of samples, concentrations of uranium fall in the range from slightly below 1 to 4 parts per million (ppm). Coals with more than 20 ppm uranium are rare in the United States (http://energy.er.usgs.gov/products/databases/ CoalQual/intro.htm).



Results for the uranium in world coals are as follows (Swaine,1990):

Australia- 0.01-4.5 ppm
Brazil- 2.7-19 ppm
Canada- 0.2-7.2 ppm
China- 0.16-21 ppm
Germany West- less than 1 – 13 ppm
India- 1.1-3.6 ppm.
New Zealand- 0.015-0.46 ppm
South Africa- 1.2- 7.3 ppm
Turkey- 1.4-6.4 ppm
UK- 1.1- 3.0 ppm.

Traces of uranium have been also found in the Permian coals of Jharkhand State of India. Areas are KDH, Dakra, Rohini, and Rai Bachra in the North Karanpura coalfield. Channeled samples were analyzed with the help of XRF instrument.

Occurrence of uranium in coals:

Three hypotheses advanced to explain the occurrence of uranium in some coals were described by Denson (1959) as follows.

1. Syngenetic: Uranium was deposited from surface waters by living plants or in dead organic matter in swamps prior to coalification.
2. Diagenetic: Uranium was introduced into the coal during coalification by waters bringing the uranium from areas marginal to the coal deposits or from the consolidating enclosing sediments.
3. Epigenetic: Uranium was introduced in the coal after coalification and after consolidation of the enclosing sediments by groundwater deriving uranium from hydrothermal sources or from unconformably overlying volcanic rocks.

Uranium is associated with clays, zircon and phosphates and may also be organically bound in coal. The accumulation of uranium in coal may vary markedly from place to place, and the occurrence of uranium in each deposit should be interpreted in relation to the geologic history of the region. Field evidence favors the epigenetic hypothesis of the origin of uranium in U.S. western coals. Secondary concentration of uranium in coal may occur when solution of small quantities of uranium by groundwater from overlying volcanic rocks is followed by downward percolation of these waters through previous strata until the uranium is taken up and retained by the highest of the underlying lignite beds. Application of this theory led to the discovery of uranium-bearing coal in Wyoming, Montana, Idaho and New Mexico.

Most thorium in coal is contained in common phosphate minerals such as monazite or apatite. In contrast, uranium is found in both the mineral and organic fractions of coal. Some uranium may be added slowly over geologic time because organic matter can extract dissolved uranium from ground water. In fly ash, the uranium is more concentrated in the finer sized particles. If during coal combustion some uranium is concentrated on ash surfaces as a condensate, then this surface-bound uranium is potentially more susceptible to leaching. However, no obvious evidence of surface enrichment of uranium has been found in the hundreds of fly ash particles examined by USGS researchers.

Most coal also contains potassium-40, lead-210, and radium-226. The total levels are generally about the same as in other rocks of the Earth's crust. Most emerge from a power station in the light flyash, which is fused and chemically stable, or the bottom ash. Some 99% of flyash is typically retained in a modern power station (90% is some older ones), and this is buried in an ash dam.

The amounts of radionuclides involved are noteworthy. In Victoria, 65 million tonnes of brown coal is burned annually for electricity production. This contains about 1.6 ppm uranium and 3.0-3.5 ppm thorium, hence about 100 tonnes of uranium and 200 tonnes of thorium is buried in landfill each year in the Latrobe Valley. Australia exports 235 Mt/yr of coal with 1 to 2 ppm uranium and about 3.5 ppm thorium in it, hence up to 400 tonnes of uranium and about 800 tonnes of thorium could conceivably be added to published export figures (http://www.world-nuclear.org/info/inf30.html).

Other coals are quoted as ranging up to 25 ppm U and 80 ppm Th. In the USA, ash from coal-fired power plants contains on average 1.3 ppm of uranium and 3.2 ppm of thorium, giving rise to 1200 tonnes of uranium and 3000 tonnes of thorium in ash each year (for 955 million tonnes of coal used for power generation). Applying these concentration figures to world coal consumption for power generation (7800 Mt/yr) gives 10,000 tonnes of uranium and 25,000 tonnes of thorium per year(http://www.world-nuclear.org/info/inf30.html).

Reference:
Berthoud, E.L. 1875. on the occurrence of uranium, silver, iron etc., in the Tertiary Formation of Colorado Territory. Proc. Nat. Acad. Sci., Philadelphia, 27, 363-365.
Breger, I.A., Deul, M. and Meyrowitz, R. 1955. Geochemistry and mineralogy of a uraniferous subbituminous coal. Econ. Geol., 50, 610-624.
Bouska, V. 1981. Geochemistry of Coal. Elsevier Scientific Publishing Company, New York.
Denson, N.M., 1959. Uranium in coal in the Western United States, U.S. Geological Survey Bull. 1055.
Gill, J.R. 1959. Reconnaissance for uranium in the Ekalaka Lignite field, Carter County, Montana. US Geological Survey, Bull. 1055.
Gott, G.B. 1952. Uranium in black shales, lignites and limestones in the United States. Selected papers on uranium deposits in the United States. U.S. Geological Survey, Circ.220,Washington. 31-35.
Swaine, D.J. 1990. Trace elements in coal. Butterworths, London.
Valkovic, V. 1983. Trace elements in coal. CRC Press, Inc. Florida.
Vine, J.D. 1956. Uranium-bearing coal in the United States. US Geol. Surv. Prof. Pap., No 300, 405-41.

Rocks of Ranchi city in India is radioactive.

Are the rocks of Ranchi city in India is Radioactive?

by

Dr. Nitish Priyadarshi

Ranchi is the capital city of the Indian state of Jharkhand.  / The total area covered by Ranchi - Municipal Area is about 110 square kilometers and the average elevation of the city is 2,140 feet above sea level.
Geographically, Ranchi is located on southern part of the Chota Nagpur plateau which forms the eastern edge of the Deccan plateau system. The area surrounding Ranchi has been endowed with natural attractions and it is referred to as the “City of Waterfalls”.
As of 2001 India census, Ranchi had a population of 846,454. Males constitute 53% of the population and females 47%.

Rocks around Ranchi:

The oldest geological formation of this district is represented by Dharwar sediments with the basic intrusive. These, being later intruded by the batholithic mass of Chota Nagpur granite, were metamorphosed into various types of schistose and gneissic rocks. The remnants of the earlier sedimentary and igneous rocks are known from the inclusions of phyllites and schists of varying dimensions in the granite mass and the extensive areas of Khondalites. Phyllites are by far the predominant rock type in the south-east portion of this district. Chota Nagpur granite gneiss forms the country rocks of the district and is a part of the enormous intrusive mass.

Within the main body, the granite gneiss varies from a normal medium- grained rock to a porphyritic material with large crystals of potash feldspar. Quartz, biotite or hornblende are the other essential minerals. Apatite, zircon, sphene are rutile are the accessories. The amphibolites occur as minor intrusive in the Khondalite series. Amphibolite also occur as minor enclaves in the granite gneisses in and around Ranchi city.

Radioactivity in the Environment:

Humans have always been exposed throughout their period of existence to naturally occurring ionising radiation. Specifically, naturally occurring radionuclides are present in variable amounts in our environment. To assess radiological health hazards, naturally occurring radionuclides are being measured in soil, sand, marble, bricks etc throughout the world.

Terrestrial radiation comes from radioactive elements that were present at the time the earth was formed. They continue to decay and form additional radioactive materials.
Unusual soil composition has increased background radiation twenty-five fold or more in a few areas in the world. Locations with high background radiation in the soil, mainly from uranium, include the Rocky Mountains, Kerala India, coastal regions of Brazil, granite rock areas of France, and the northern Nile Delta.
In the United States, lower background radiation is seen in the sandy soils of the Atlantic and Gulf coastal plains.


The distribution of naturally-occurring uranium, radon, and other radioactive elements, radionuclides, depends on the distribution of rocks from which they originate and the processes which concentrate them. The key therefore is to know the distribution of source-rock materials containing elevated levels of radionuclides and to understand the physical and geochemical processes that concentrate radionuclides."

Gamma and alpha radiation emitted by radioactive elements in rocks and soils, especially those that decay quickly (such as radon), pose a health risk. This radiation is implicated in cancers of the lung, bone, and of other organs.

Radioactivity generated by those radioactive elements that exist in the Earth's crust. All the elements from polonium (atomic number 84) to uranium (atomic number 92) are radioactive. Radioisotopes of some lighter elements are also found in nature (for example potassium-40).

Radioactive gases such as radon are found in soil and may seep upwards into buildings.

Radioactivity in Ranchi soil:

Seeing the rock types and its mineral composition background or radioactive radiation cannot be ruled out in Ranchi. This fact was justified by a published report of Research Reactor Institute, Kyoto University. According to the report Air-gamma dose rate was 0.30 μSv/h on the surface in the densely populated area in the city. In Ranchi the concentration of K-40 (potassium-40) and thorium is high. Concentration of Radium-226 was 75 Bq/Kg in the soils.

Very interesting thing in the Ranchi city is that name of one of its major road is RADIUM ROAD. Till today no body knows from where did this name came from. Name of this road exists from the British rule in India i.e. before 1947.

Potassium 40 is found in potassium feldspar (orthoclase), muscovite, and amphibole.
Uranium may be found in zircon ,urananite ,monazite ,apatite and sphene . Seeing the presence of apatite, sphene and zircon in the Ranchi rocks, presence of Uranium cannot be ruled out. According to the report Uranium concentration is also high in Ranchi. All these concentrations are of natural origin. Radioactivity in the bricks made by the local soil may pose threat to the people living in the houses made by these bricks.

When Uranium is there, presence of Radon cannot be ruled out. It is radioactive gas that comes up from the soil and collects in basements and ground floors, sometimes in well water. Radon is a prominent villain in the United States, blamed for tens of thousands of deaths from lung cancer.

Radon is relatively high in uranium-rich rocks such as ancient granites, like Ranchi, high-organic shales and coal beds.

There are areas in the world where the content of the uranium or thorium in soil are high, and the people are receiving exposure of 10 or more times in such a place compared with other areas. There is no other way but to accept. Ranchi, the capital of Jharkhand, is one of such the places.

Health effects:

Potassium-40 can present both an external and internal health hazard. In the body, potassium-40 poses a health hazard from the both the beta particles and gamma rays. . The health hazard of potassium-40 is associated with cell damage caused by the ionizing radiation that results from radioactive decay.

There is no evidence that exposure to naturally present levels of radium has harmful effects on human health. However, exposure to higher levels of radium may result in health effects, such as teeth fracture, anaemia and cataract.

Radium is constantly produced by the radioactive decay of uranium and thorium. Radium is present at very low levels in rocks and soil and strongly attaches to those materials. It is also found in air. High concentrations of radium exist in water on some locations.Uranium mining results in higher levels of radium in water near uranium mines. Plants absorb radium from the soil. Animals that eat these plants will accumulate radium.Finally, radium may concentrate in fish and other aquatic organisms and bio magnify up the food chain.
People will always be exposed to small amounts of thorium through air, food and water, because it is found nearly everywhere on earth.All people absorb some thorium through food or drinking water, and the amounts in air are so small, that the uptake through air can usually be ignored. Breathing in thorium in the workplace may increase the chances of development of lung diseases and lung and pancreas cancer many years after people have been exposed. Thorium has the ability to change genetic materials.
Seeing the high concentration of thorium (210 Bq/kg) people of Ranchi may face some thorium exposures.

Conclusion:
Even the exposure in Ranchi city may be of very low dose, exposure to radiation accompanies risk. However, since the natural activity exists on the earth and there is a radiation such as a cosmic ray, we cannot escape the exposure completely. Seeing the possibilities of Radon gas, houses built in Ranchi should be proper ventilated and making of basements should be avoided.

Reference:

Priyadarshi, N. 1998. A handbook geology of Chotanagpur, Aoyushi Publications, Ranchi, India.

http://encyclopedia.farlex.com/natural+radioactivity

http://encyclopedia.farlex.com/background+radiation