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

How geology affected both ancient and modern human settlements.

Primitive tribe were attracted towards the forest and hilly terrain of Jharkhand state, India.

by

Dr. Nitish Priyadarshi

Geology has a remarkable influence on our lives today, as it has on all life since the beginning billions of years ago. Perhaps the clearest influence we see of this is through the development of wealth from the exploitation of fossil fuels and mineral resources, including precious metals and gems. Wars have been fought over (and with) these resources, and for the potential wealth they represent. However, geology has other profound, if less glamorous, impacts on civilization, both past and present. For example, the productivity of soils critically depends on the underlying geology—both for its mineral composition and its capacity to store water. Geology also determines the shape of our landscapes—that is, before being disturbed by humans—and it is the shape of the land that has determined the distribution of human populations throughout our history.

Back at the dawn of human civilization when we lived along the Nile, the river regularly flooded and would bring nutrients and minerals back to the croplands. That is what sustained early human civilization. The dawn of agriculture was dependent on the flooding of a river. Had that river not flooded and that land been farmed over and over again from generation to generation, the civilization there would have died due to malnutrition. It could not have sustained itself.

The origin of urbanization had been sought from speculations and deductions of observable facts. The first cities must have originated from the development of settled agriculture, where agriculture economy in which the cultivation of cereals was an important element.

The first civilization originated along the river valleys as the water played major role in both day to day life and in agriculture.

The earliest examples of the urban development originated on the bank of the Tigris and the Euphrates between 5000 to 3000 B.C. Various technological inventions such as the wheeled cart, ox-drawn plough, sailing boat, system of canal irrigation, development of pottery and metallurgy brought changes in the economic and social organization.

The main geological factors influenced the ancient urbanization are as follows:-
1. Nature of the topography.
2. Local weather conditions.
3. Availability of water.
4. Quality of soil.
5. Nature of surface and sub-surface water.
6. Presence of minerals and rocks.

The influence of these factors varied from time to time in various forms and on the sizes of rural settlements.

Certain factors were considered by our ancestors when the site was selected for settlement such as availability of water, high ground in easily flooded areas etc. Japanese farming villages for example are tightly packed together, so that only the narrowest passage ways remain between the houses. This reflects the need to allocate every possible square meter of land for farming.

Hills:

In early period people led an insecure life especially in the border areas. In such places the settlements were either located on top of a hill or in the meander loop of a river or on high place near valleys to assure protection. Hills and mountains also provided caves to early settlers as their natural home.

Durham in England was built on a hill protected on three sides by the meander of the river water. Pithoria, near Ranchi city in Jharkhand State of India, was also selected as the earlier capital town (1st century AD) by Munda tribe because from one side there is steep valley and from other side it is covered with hills. It acted as natural protection from the invaders.


Pithoria was also rich in ground water reservoir which also attracted the early settlers like Munda and Nagvanshi rulers to develop this area as their first capital.

Rocks as building material:

Rocks were earlier used as the building material especially sandstone. Many such ancient buildings and temples are found in India where sandstone and granites were used.

Sandstone has a long history in the building industry. The stone generally has a uniform texture and it is somewhat soft, making it a user-friendly stone for a variety of applications. It is favored for wall claddings because of its low absorption rate, high compression strength and aesthetically pleasing appearance. Its appearance and high durability make it ideal for flooring as well. With a variety of colors and finishes, it is also easy to match it to nearly any décor.Massive sandstones consisting of closely interlocking and angular grains and free from structural defects were found best for building purposes. Most of the sandstones used in the buildings in ancient city of Varanasi in India, may have been supplied from Vindhyan System. The Vindhyan sandstones are fine grained in texture and available in abundance in a variety of colours like white, cream, and deep red and grey etc.Vindhyan sandstones are regularly quarried in area very near to Varanasi in Uttar Pradesh.

The stone is a common paving material because it can be highly weather resistant. Due to such quality these stone was used in mass scale in constructing stairs near the banks of the holy river Ganges in India. As a paver, sandstone is prized for its ability to maintain age and appearance over time, as well as for the different dimensions available.
Sandstone pavers can be used for patios, pool surrounds, pool coping, balconies, as well as cladding and veneer.
The color of sandstone is extremely varied and depends on the quantity and color of the cementations materials present and the overall color of the mineral grains. Sandstone spans the full spectrum of colors, ranging from sandy yellows to deep gold, pale pinks and light greens.
Light colors generally result from the absence of cementitious materials, or joined by calcite or quartz. Buff, brown and red colors result from the presence of limestone and hematite. Greensand, a type of green sandstone, results from the presence of glauconite.

Water:

Perhaps the essential ingredient to any viable civilization is access to water. Nearly all the great civilizations the world grew up around water, which provided the key not only to supplying freshwater, but also to agriculture, trade, transport and defense. Such civilizations as the Roman Empire, Egyptian Civilization, the Venetian Empire and the Omayyad Dynasty were all founded on their access to water, which provided their population with the means to both survive and expand.

Water is a vital need and man from time immemorial settled nearer to the source of water. In some places especially in limestone region people select the spring locations the site for settlements. These springs occur in a line at the line of contact of the permeable and impermeable layer. Such settlements are referred to as spring line settlements e.g. spring line villages are seen in South Dover in England and in Jammu and Kashmir State in India.

In dry areas settlements have the tendency to get oriented nearer to the sources of water. Hence the settlement site was located near a spring or river. These settlements were found ore are found in the dry limestone and other regions as well as in deserts.

World's major ancient civilizations flourished near river banks and deltaic sea coasts. The reason behind is the easy availability of water, a vital requirement of human beings. However, this choice of sites with easily available water has also cost dear to them. The change of river courses and sea level fluctuations led to the devastation of well-established civilizations. The drowning of ancient settlements due to raised sea level, forms the common subject matter of interest to marine archaeologists and marine geologists. While, marine archaeologists pay more attention to cultural aspects of those ancient people, marine geologists are interested in sea level fluctuations that cause the rise and fall of these civilizations. Marine archaeologists make use of artifacts, whereas marine geologists utilize the sediments and marine organisms to unravel the past. Since the common aim of both, the marine geologists working on palaeoclimate and the archaeologists is to illuminate the past, it becomes necessary to bring coherence between the two. In the Indian context, some attempts were made to use the understanding of sea level fluctuations to explain the archaeological discoveries. Nigam et al. (1990) collected the evidences of sea level fluctuations from religious, archaeological records and successfully supplemented with inferences from the marine geological studies.

Discovery of Lothal dockyard (first naval dockyard of the world as claimed by archaeologists) in Gujarat and drowning of Dwarika on the west coast and Pumpahar on the east coast of India are important examples of the role of the sea level fluctuations in shaping the history of mankind in this part of the world. The discovery of the Lothal dockyard, an important and famous name in Indian cultural heritage, provides evidence of ancient Indian interest in maritime activities around 4500 years B.P.

The Ganga-Ganges, especially, is the river of India, around which are intertwined the countries memories, culture and history. She has been a symbol of India's age-long culture and civilization, ever changing, ever flowing, and yet ever the same Ganga-Ganges.

The history of Ganga-Ganges is as long as the history of Indian civilization. It was in this plain that the great kingdoms of Magadha, Gupta, and Mughals found their home. It is also the region that created one of the most homogenous cultures of all times in the civilizations of the world. It was also the place which created the essence of Hinduism, Buddhism, Jainism, and Sikhism.


In the low lying areas and the delta areas, which were prone to floods and in the equatorial regions where damp and marshy conditions prevailed, settlements had the tendency to seek dry sites. Generally the hill site some 30 m above the surface land were preferred. Still today they are following the same pattern. Such settlements are known as dry point villages.

The foot hill region offers some possibilities for settlements. The foot hill region has the advantage of collecting products from the mountains as well as from the adjacent plains.

Volcanoes:

Volcanoes are also playing major role from ancient civilization to present. Volcanoes are known for their violent eruptions and lava flows, but there are many benefits that volcanoes provide for society. Volcanoes help enrich soil for farming and in some cases provide reservoirs for the storage of ground water. Moreover the earth's valuable resources are formed in volcanoes. These elements include fluorine, sulfur, zinc, copper, lead, arsenic, tin, molybdenum, uranium, tungsten, silver, mercury, and gold. Society makes use of all of these elements that volcanoes help to provide. Geothermal power is an alternate energy source that is better for the environment and volcanoes provide this to society also. Although volcanoes have the reputation of being very dangerous, (Volcanoes can kill people and animals. They can be very destructive.) There nevertheless are advantages of living near a volcano.

When a volcano erupts it throws out a lot of ash. At short notice this ash can be very harmful to the environment, but on the long term the ash layer, which contains many useful minerals, will be converted to a very fertile soil.

Close to an erupting volcano the short-term destruction by pyroclastic flows, heavy falls of ash, and lava flows can be complete, the extent of the damage depending upon the eruption magnitude. Crops, forests, orchards, and animals grazing or browsing on the volcano's slopes or surrounding lowland can be leveled or buried. But that is the short-term effect. In the long run, volcanic deposits can develop into some of the richest agricultural lands on earth.

One example of the effect of volcanoes on agricultural lands is in Italy. Except for the volcanic region around Naples, farming in southern Italy is exceedingly difficult because limestone forms the basement rock and the soil is generally quite poor. But the region around Naples, which includes Mount Vesuvius, is very rich mainly because of two large eruptions 35,000 and 12000 years ago that left the region blanketed with very thick deposits of tephra which has since weathered to rich soils. Part of this area includes Mount Vesuvius. The region has been intensively cultivated since before the birth of Christ. The land is planted with vines, vegetables, or flowers. Every square foot of this rich soil is used. For example, even a small vineyard will have, in addition to grapes and spring beans on the trellises, cauliflower and onions between the trellis rows, and the vineyard margin rimmed with orange and lemon trees, herbs, and flowers. It also is a huge tomato growing region.

The verdant splendor and fertility of many farmlands of the North Island of New Zealand are on volcanic soils of different ages. Volcanic loams have developed on older (4,000 and 40,000 years old) volcanic ash deposits of the Waikato and Bay of Plenty regions. Combined with ample rainfall, warm summers, and mild winters, these regions produce abundant crops, including the kiwifruit found around the world in modern recipes. The altered volcanic ashes are well-drained, yet hold water for plants, and are easily tilled. Deep volcanic loams are particularly good for pasture growth (there is a large New Zealand dairy industry), horticulture, and maize.
Nearly everywhere volcanoes are located people use the rich soil for farming. Even after an eruption people still return because of the fertile soil around the volcano.

Rocks and minerals:

In ancient days rocks and minerals played the important role for the earlier settlements. Best example is that of Jharkhand State of India, where the primitive tribe like Asur and Birhors were attracted towards the forest and hilly terrain of this state. Causes may be the presence of minerals and stones. Iron-smelting used to be the principal occupation of the Asurs. Asur used to extract iron ore for iron smelting from the laterite rocks present in this state.

A study of the early iron technology of Bihar, Jharkhand and West Bengal state in India, is of special importance from the point of view of proper understanding of the nature and character of iron age cultures which developed and flourished in this region during the period ranging from protohistoric to the historical period. The early beginning of the use of iron in this region was initially noted in the late Chalcolithic cultural phase.

Since the beginning of civilization, people have used stone, ceramics and, later, metals found on or close to the Earth's surface. These were used to manufacture early tools and weapons, for example, high quality flint found in northern France and southern England were used to create flint tools. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Graves are especially famous, and like most other flint mines, are Neolithic in origin (ca 4000 BC-ca 3000 BC). Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District.
The oldest known mine on archaeological record is the "Lion Cave" in Swaziland. At this site, which by radiocarbon dating proves the mine to be about 43,000 years old, paleolithic humans mined mineral hematite, which contained iron and was ground to produce the red pigment ochre. Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools.

The study of rocks and minerals is one of the taproots of science, perhaps not as deep as astronomy, but extending well back into prehistory. Paleolithic people recognized and sought specific rocks and minerals for cutting tools, pigments, and various practical, religious, or artistic objects. The first minerals that were known and sought for their favorable properties were micro-crystalline ( micro crystalline means too small to be seen without a microscope) varieties of quartz, particularly flint.
Reference:

NIGAM, R., HASHIMI, N.H. and PATHAK, M.C. (1990) Sea level fluctuations: Inferences from religious and archaeological records and their oceanographic evidences. Jour. Mar. Archaeol., v.l, ñp.16_18.

http://www.naturalnews.com/020072.html
http://web.bcsdny.org/flhs/science/greece/
http://www.umich.edu/~gs265/society/volcanoes.htm
http://volcanology.geol.ucsb.edu/soil.htm
http://drs.nio.org/drs/bitstream/2264/241/1/J_Geol_Soc_India_59_583.pdf
http://unesco.uiah.fi/water/material/03_water_and_civilisation_html

Think twice before using radioactive granite for decorative purpose in your house- radiation may affect you.

Granite rocks in some parts of Jharkhand State of India is highly radioactive- says research.

By

Dr. Nitish Priyadarshi

A physics professor at Rice University is warning of a radioactive threat found in some kitchen countertops.
Some granite countertops contain levels of uranium high enough to be dangerous to humans, said Rice professor W.J. Llope.

Using a spectrometer, Llope tested 25 varieties of granite bought from Houston-area dealers. In some cases, he said, he found countertops that could expose homeowners to 100 millirems of radiation in just a few months — the annual exposure limit set by the Department of Energy for visitors to nuclear labs.

Scientists at the national geophysical research institute (NGRI) of India have disturbing news for residents of Hyderabad city especially those living in rocky Banjara and Jubilee hills area. They have found that the granite rocks of Hyderabad have abnormally high concentrations of radioactive uranium and thorium compared to elsewhere in southern India. Team has measured the radioactivity of rocks from nearly 2,000 locations in the states of Karnataka, Tamil Nadu and Andhra Pradesh and nowhere did they find it to be as high as in Hyderabad.

Rocks in the western part of Hyderabad are more radioactive compared to those in the east. Rocks in the posh areas of jubilee and Banjara hills have twice as much uranium as found in Uppal in the southeastern part of the city.

The uranium content of Hyderabad granites varied from 10 parts per million (ppm) to 25 ppm in contrast to 0.23 ppm for Chennai and 1.7 ppm to 7.5 ppm for Bangalore. The thorium content of Hyderabad granites was also found to be four to five times higher than that of Bangalore. These high values of radioactive elements could pose a health hazard.

According to A. M. El Arabi, N. K. Ahmed and K. Salahel Din of Physics Department, South Valley University, Qena, Egypt, the average dose rates values for outdoor and indoor air for Elba granites of Egypt are found to be three times higher than the world average. Whereas, the corresponding average values for Qash Amir and Hamra Dome granites are five and six times higher than the world average, respectively. Thus, this information is an important alert for the local people to avoid the use of these granites in the construction of dwelling without radioactivity control.

While most experts agree that only a small percentage of granite in homes today poses any health risk, the current debate centers on identifying granite that might emit radiation and determining under what circumstances a danger occurs.

All rocks have a small amount of radioactivity in them due to the presence of minerals that contain radioactive elements uranium (U), thorium (Th) and potassium-40 (40K). Because granite typically contains more of these elements than most other rocks, it will be more radioactive than a slate or marble. All of the minerals in granite contain some radioelements; the white or pink feldspars contain 40K, the black biotites and horn-blendes contain 40K, U and Th, and the small inclusions of minerals such as zircon, apatite, sphene, etc. contain the most U and Th.

People living in granite areas or on mineralized sands receive more terrestrial radiation than others, while people living or working at high altitudes receive more cosmic radiation. A lot of our natural exposure is due to radon, a gas which seeps from the earth's crust and is present in the air we breathe.

It has been established that human exposure to radioactivity comes mainly from natural sources. The natural radiation to which the general public is exposed consists of two components, namely, internal exposure and external exposure. Internal exposure is due to the inhalation of radon gas in the air and the intake of traces of radio nuclides in food and drinking water. External exposure arises from terrestrial gamma rays and cosmic radiation incident on the earth’s surface. In fact, only about 15% of the total effective dose is derived from cosmic radiation and about 0.6% is attributable to cosmogenic radio nuclides. The members of the radioactive decay chains of 232Th (14%), 235U and 238U (55.8%), along with 40K (13.8%) are responsible for the main contributions to the dose from natural radiation, while a more than 0.3% is due to the effect of 87Rb.

Many natural rocks contain radioactive elements such as 238U, 226Ra, 232Th and 40K. Although these radio nuclides are widely distributed, their concentrations depend on geological and geographical conditions and as such they vary from place to place.

In geology, rock is a naturally occurring aggregate of minerals. Rocks have had a huge impact on the cultural and technological advancement of the human race. Rocks especially granite have been used by Homo sapiens and other hominids for more than 2 million years. The prehistory and history of civilization is classified into the Stone Age, Bronze Age, and Iron Age. Although the stone age has ended virtually everywhere, rocks continue to be used to construct buildings and infrastructure.

But now a days rock (granite) are now seen as source of dangerous radioactivity. It is in the form of natural background radiation which affects the humans. Humans have always been exposed throughout their period of existence to naturally occurring ionizing radiation.

Geologically the term granite is placed under felsic or acidic divisions. It refers to a rock composed mainly of quartz and feldspar as essential minerals. The dark minerals like biotite, tourmaline and few of amphiboles groups, etc. occur as minor constituents of granite. Granite is the typical example of relatively coarse- grained plutonic rocks that crystallized slowly in large masses within the crust.

Granite is actually rather radioactive and has 5 to 20 times the concentration of uranium compared to other common rock types. Some health concern exists in areas that are rich in granitic terrain, as background radiation is enhanced by the presence of large granite bodies. Although the uranium is generally not concentrated enough to make granite a uranium ore, the leaching and erosion of granite has helped produce most of the uranium ore deposits around the world.

Some granites contain around 10 to 20 parts per million of uranium. By contrast, more mafic rocks such as tonalite, gabbro or diorite have 1 to 5 ppm uranium, and limestones and sedimentary rocks usually have equally low amounts. Granite could be considered a potential natural radiological hazard as, for instance, villages located over granite may be susceptible to higher doses of radiation than other communities.

Granite has been extensively used as a dimension stones and as flooring tiles in public and commercial buildings and monuments. Because of its abundance, granite was commonly used to build foundations for homes in New England. With increasing amounts of acid rain in parts of the world, granite has begun to supplant marble as a monument material, since it is much more durable. Polished granite is also a popular choice for kitchen countertops due to its high durability and aesthetic qualities.

People using granites, containing high uranium, for decorative purpose inside house may be affected with radiation.

People of Ranchi and other parts of Jharkhand state of India are frequently using polished granites for different decorative purpose without knowing how much uranium is present in the stone. Author has earlier warned the people of Ranchi about the possibility of radioactivity in Ranchi rocks. People using local granites or brought from Hyderabad, for decorative purpose, should be more cautious.

Even the granites of the Daltonganj area of Jharkhand state contain anomalous uranium values. Uranium mineralization has also been observed in the granitic rocks comprising the southern periphery of the Hutar basin of Daltonganj area. The Proterozoic granitoids, forming the provenance for the Hutar and Auranga subbasin, have been analyzed which revealed uranium content up to 520 ppm. ( Virnave, 1999).

As demand for granite has increased, exotic stones are being imported from remote corners of the world and greater scrutiny is needed. Lots of varieties of granite are sold for household use in the Jharkhand State. None of them is routinely tested for radioactivity. Even the businessman selling granites are in regular contact with the radiation.

People must go for alternative decorative stones like sandstone or marble, having low uranium, other than using radioactive granites. Even if they are using granites, their houses should be proper ventilated so that the poisonous gases can be flushed out.

Sources:

A. M. El Arabi, N. K. Ahmed and K. Salahel Din. ASSESSMENT OF TERRESTRIAL GAMMA RADIATION DOSES FOR SOME EGYPTIAN GRANITE SAMPLES. Radiation Protection Dosimetry 1-4 (2007).

Bruzzi, L., Baroni, M., Mele, R. and Nanni, E. Proposal for a method of certification of natural radioactivity in building materials. Radiolo. Protec. 17(2), 85–94 (1997).

Iqbal, M., Tufail, M. and Mirza, S. M. Measurement of natural radioactivity in marble found in Pakistan using a NaI(Tl) gamma-ray spectrometer. Environ. Radioact. 51, 255–265 (2000).

Virnave, S.N. Nuclear Geology and Atomic Mineral Resources. Bharati Bhawan, Patna. 169.

http://www.world-nuclear.org/images/info/decayseries.gif
http://en.wikipedia.org/wiki/Granite
http://www.galleries.com/rocks/granite.htm
http://timesofindia.indiatimes.com/articleshow/387896063.cms
http://medwelljournals.com/fulltext/erj/2008/348-350.pdf http://www.gogostone.com/info/detail/12-1534.html

Varanasi ancient buildings made of Sandstones

Varanasi ancient buildings made of Sandstones.

By
Dr. Nitish Priyadarshi

From my childhood I visited the holy city of India Varanasi. Whenever I use to visit the Ganges river I always admire the big buildings on the bank of the holy river. I was always overwhelmed by the charm and structure of these ancient buildings. Most of the ancient temples and structures along the ghats have been destroyed. What remain are mainly 18th and 19th century buildings. According to the local people age of these buildings are more than 100 to 150 years. But they are still standing looking fresh as if it has been recently build up by the Maharajas. What fascinated me the most is the stones used in the buildings. All the stones were in the size of big slabs which are now not so commonly used. As a geologist I studied the rocks and it was found that most of the buildings were built with Sandstones. As compared to new houses and other houses these buildings looks more strong and weathered proof.

Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, gray and white.

Some sandstones are resistant to weathering, yet are easy to work. This makes sandstone a common building and paving material. Because of the hardness of the individual grains, uniformity of grain size and friability of its structure, sandstone is an excellent building material. . In most sandstone used for building, quartz grains predominate.

Sandstone also has a long history in the building industry. The stone generally has a uniform texture and it is somewhat soft, making it a user-friendly stone for a variety of applications. It is favored for wall claddings because of its low absorption rate, high compression strength and aesthetically pleasing appearance. Its appearance and high durability make it ideal for flooring as well. With a variety of colors and finishes, it is also easy to match it to nearly any décor.

Massive sandstones consisting of closely interlocking and angular grains and free from structural defects was found best for building purposes. Most of the sandstones used in the buildings may have been supplied from Vindhyan System. The Vindhyan sandstones are fine grained in texture and available in abundance in a variety of colours like white, cream, and deep red and grey etc.

Vindhyan sandstones are regularly quarried in area very near to Varanasi in Uttar Pradesh.
The rock's formation occurs in two phases: The first is sedimentation, where layers of sand accumulate via water or air; the second is compaction, which occurs when pressure is exerted from overlaying materials and precipitation within the pore spaces between the sand grains. Sandstone is formed in layers and, over time, the layers become compacted until the bottom layers slowly turn into rock.

The stone is a common paving material because it can be highly weather resistant. Due to such quality these stone was used in mass scale in constructing stairs near the banks of the holy river. As a paver, sandstone is prized for its ability to maintain age and appearance over time, as well as for the different dimensions available. Sandstone pavers can be used for patios, pool surrounds, pool coping, balconies, as well as cladding and veneer.
The color of sandstone is extremely varied and depends on the quantity and color of the cementations materials present and the overall color of the mineral grains. Sandstone spans the full spectrum of colors, ranging from sandy yellows to deep golds, pale pinks and light greens.
Light colors generally result from the absence of cementitious materials, or joined by calcite or quartz. Buff, brown and red colors result from the presence of limestone and hematite. Greensand, a type of green sandstone, results from the presence of glauconite.
Dr. Nitish Priyadarshi
Geologist