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What Is Radon Gas?

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What Is Radon Gas?

By EnviroVent May 02, 2016

Radon is produced from the natural radioactive decay of uranium, which is found in all rocks and soil. Radon can also be found in water. Radon escapes easily from the ground into the air, where it decays and produces further radioactive particles.

Radon is a colourless, odourless radioactive gas. It is formed by the radioactive decay of the small amounts of uranium that occur naturally in all rocks and soils. Radioactive elements decay and emit radiation. Any exposure to this type of radiation is a risk to health - radiation is a form of energy and can cause damage in living tissues increasing the risk of cancer.

Radon is a dangerous radioactive gas which can't be detected by humans, as it is invisible and has no smell or taste. It accounts for half of the radiation we are all exposed to daily, with the other half coming from a mix of sources. At normal levels, this radiation is harmless, but exposure to a radiation source like radon above safe levels is dangerous and can cause serious health problems. 

Radioactivity is where unstable elements, such as naturally occurring uranium, thorium and radon, break down; energy is released and different elements formed. The new elements may also be unstable so the process is repeated until a stable element is formed. The energy given off is called radiation and can be alpha or beta particles or gamma rays. Alpha particles are more harmful than beta particles or gamma rays. This is because alpha particles contain more energy and are absorbed over a smaller area.

Unlike all the other intermediate elements in the aforementioned decay chains, radon is, under normal conditions, gaseous and easily inhaled. Radon gas is considered 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, such as uranium-containing minerals, 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.

Radon has been used in some spas for presumed medical effects. In addition, radon is used to initiate and influence chemical reactions and as a surface label in the study of surface reactions. It has been obtained by pumping the gasses off of a solution of a radium salt, sparking the gas mixture to combine the hydrogen and oxygen, removing the water and carbon dioxide by adsorption, and freezing out the radon.

Radon mitigation is any process used to reduce radon gas concentrations in the breathing zones of occupied buildings, or radon from water supplies. Radon is a significant contributor to environmental radioactivity. 

Why is Radon Gas Dangerous? 

The video shown below from propertECO gives a quick overview of the important facts that all homeowners, landlords and employers should be aware of.

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 enters homes through cracks in the floors or at floor-wall junctions, gaps around pipes or cables, small pores in hollow-block walls, or sumps or drains. Radon levels are usually higher in basements, cellars or living spaces in contact with soil.

Radon concentrations vary between adjacent homes, and can vary within a home from day today and from hour to hour. Residential radon levels can be measured in an inexpensive and simple manner. Because of these fluctuations, it is preferable to estimate the annual mean concentration of radon in indoor air by measurements for at least 3 months. However, measurements need to be based on national protocols to ensure consistency as well as reliability for decision-making.

Where does Radon gas come from?

Radon is a  radioactive gas. You cannot see, smell or taste radon, but it may be a problem in your home. It was discovered by English physicist Ernest Rutherford in 1899 and can only be detected using specialist equipment. 

All soil and rocks naturally contain small amounts of uranium. As this element decays, radon is formed, which then rises to the surface. It is found everywhere, and is always at safe levels outdoors. However, it can be at dangerously high levels in buildings, depending on the part of the country, and the type of ground the building is on. Other significant factors include the design and materials used in the building, and the habits of the occupants. Two neighbouring houses might have varying levels of radon.

Radon is produced by the radioactive decay of radium-226, which is found in uranium ores, phosphate rock, shales, igneous and metamorphic rocks such as granite, gneiss, and schist, and to a lesser degree, in common rocks such as limestone. Every square mile of surface soil, to a depth of 6 inches (2.6 km2 to a depth of 15 cm), contains approximately 1 gram of radium, which releases radon in small amounts to the atmosphere. On a global scale, it is estimated that 2,400 million curies (90 EBq) of radon are released from soil annually.

Radon concentration can differ widely from place to place. In the open air, it ranges from 1 to 100 Bq/m3, even less (0.1 Bq/m3) above the ocean. In caves or aerated mines, or ill-aerated houses, its concentration climbs to 20–2,000 Bq/m3.

Radon concentration can be much higher in mining contexts. Ventilation regulations instruct to maintain radon concentration in uranium mines under the "working level", with 95th percentile levels ranging up to nearly 3 WL (546 pCi 222Rn per liter of air; 20.2 kBq/m3, measured from 1976 to 1985). The concentration in the air at the (unventilated) Gastein Healing Gallery averages 43 kBq/m3 (1.2 nCi/L) with maximal value of 160 kBq/m3 (4.3 nCi/L).

Radon mostly appears with the decay chain of the radium and uranium series (222Rn), and marginally with the thorium series (220Rn). The element emanates naturally from the ground, and some building materials, all over the world, wherever traces of uranium or thorium can be found, and particularly in regions with soils containing granite or shale, which have a higher concentration of uranium. Not all granitic regions are prone to high emissions of radon. Being a rare gas, it usually migrates freely through faults and fragmented soils, and may accumulate in caves or water. Owing to its very short half-life (four days for 222Rn), radon concentration decreases very quickly when the distance from the production area increases. Radon concentration varies greatly with season and atmospheric conditions. For instance, it has been shown to accumulate in the air if there is a meteorological inversion and little wind.

High concentrations of radon can be found in some spring waters and hot springs. The towns of Boulder, Montana; Misasa; Bad Kreuznach, Germany; and the country of Japan have radium-rich springs that emit radon. To be classified as a radon mineral water, radon concentration must be above 2 nCi/L (74 kBq/m3). The activity of radon mineral water reaches 2,000 kBq/m3 in Merano and 4,000 kBq/m3 in Lurisia (Italy).

Natural radon concentrations in the Earth's atmosphere are so low that radon-rich water in contact with the atmosphere will continually lose radon by volatilization. Hence, ground water has a higher concentration of 222Rn than surface water, because radon is continuously produced by radioactive decay of 226Ra present in rocks. Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone because of diffusional losses to the atmosphere.

We are all exposed to radiation from natural and man-made sources. Just 20 Bq m-3 (the average radon level in UK homes) gives us half our exposure to radiation from all sources. Higher radon levels give higher exposures: that is why it is important to find out the levels in your home and in your school or workplace.

Early Uses of Radon

An early-20th-century form of quackery was the treatment of maladies in a radiotorium. It was a small, sealed room for patients to be exposed to radon for its "medicinal effects". The carcinogenic nature of radon due to its ionizing radiation became apparent later on. Radon's molecule-damaging radioactivity has been used to kill cancerous cells, but it does not increase the health of healthy cells. The ionizing radiation causes the formation of free radicals, which results in genetic and other cell damage, resulting in increased rates of illness, including cancer.

Exposure to radon, a process known as radiation hormesis, has been suggested to mitigate autoimmune diseases such as arthritis. As a result, in the late 20th century and early 21st century, "health mines" established in Basin, Montana attracted people seeking relief from health problems such as arthritis through limited exposure to radioactive mine water and radon. The practice is discouraged because of the well-documented ill effects of high-doses of radiation on the body.

Radon Today

Radon emanation from the soil varies with soil type and with surface uranium content, so outdoor radon concentrations can be used to track air masses to a limited degree. This fact has been put to use by some atmospheric scientists. Because of radon's rapid loss to air and comparatively rapid decay, radon is used in hydrologic research that studies the interaction between groundwater and streams. Any significant concentration of radon in a stream is a good indicator that there are local inputs of groundwater.

Radon soil-concentration has been used in an experimental way to map buried close-subsurface geological faults because concentrations are generally higher over the faults. Similarly, it has found some limited use in prospecting for geothermal gradients.

Some researchers have investigated changes in groundwater radon concentrations for earthquake prediction. Radon has a half-life of approximately 3.8 days, which means that it can be found only shortly after it has been produced in the radioactive decay chain. For this reason, it has been hypothesised that increases in radon concentration is due to the generation of new cracks underground, which would allow increased ground water circulation, flushing out radon. The generation of new cracks might not unreasonably be assumed to precede major earthquakes. In the 1970s and 1980s, scientific measurements of radon emissions near faults found that earthquakes often occurred with no radon signal, and radon was often detected with no earthquake to follow. It was then dismissed by many as an unreliable indicator. As of 2009, it was under investigation as a possible precursor by NASA.

Radon is a known pollutant emitted from geothermal power stations because it is present in the material pumped from deep underground. It disperses rapidly, and no radiological hazard has been demonstrated in various investigations. In addition, typical systems re-inject the material deep underground rather than releasing it at the surface, so its environmental impact is minimal.

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.

To date, epidemiological studies have not found an association between consumption of drinking-water containing radon and an increased risk of stomach cancer. Radon dissolved in drinking-water can be released into indoor air. Normally, a higher radon dose is received from inhaling radon compared with ingestion.

The "WHO guidelines for drinking water quality" recommend that screening levels for radon in drinking-water be set on the basis of the national reference level for radon in air. In circumstances where high radon concentrations might be expected in drinking-water, it is prudent to measure radon concentrations. Straightforward and effective techniques exist to reduce the concentration of radon in drinking-water supplies by aeration or using granular activated carbon filters.

The health risks of Radon gas

The primary routes of potential human exposure to radon are inhalation and ingestion. Radon in the ground, groundwater, or building materials enters working and living spaces and disintegrates into its decay products. Although high concentrations of radon in groundwater may contribute to radon exposure through ingestion, the inhalation of radon released from water is usually more important.

High levels of radiation are dangerous, as radon causes radioactive dust in the air. This can become trapped in our airways, and continue to emit radiation, including dangerous alpha particles. The damage this causes to tissues increases the risk of lung cancer, with this risk going up as levels of radon and exposure times rise. Due to the nature of Radon it can be described as an invisible killer, like carbon monoxide. 

Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked. The early signs and symtoms of lung cancer to be aware of; 

  • 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.

Those at most risk of exposure to Radon and therefore it’s dangers are people that are subject to confined air spaces, particularly in underground work areas such as mines and buildings. However Radon can also affect water supplies, as elevated radon levels can occur in private water supplies.

What is a safe level of Radon gas?

Radon is measured in units called becquerels, and these are calculated per cubic metre. Generally speaking, a level below 100 Bq/m³ is considered low risk, and the UK average is far below this at 20 Bq/m³. As the radon level rises past the 100 Bq/m³ point, the risk begins to increase. Testing radon levels is simple, and merely involves placing a radon testing device in your home for at least 7 days to ensure an accurate reading is gathered. If you live in an area where high radon levels are more likely, it is recommended that you test your home. You can see the level of Radon in your area by using the Public Health England's interactive map. You can also order a Radon detector, like a carbon monoxide detector they can be placed on a shelf but they can be damaged by heat or submersion in water and should not be opened.

If you opt to do this and discover levels to be within the safe zone, you can rest assured that there is a low risk. If, however, you find that there are dangerous levels of radon in your home, there are actions you can take to lower them to within the safe limits.

Six facts to know about Radon gas

1. It is invisible and has no smell or taste.

2. You can purchase a detector and similarly to a carbon monoxide leave it on a shelf and it will alert you if it detects any Radon.  

3. Certain areas are much higher than others.

4. Radon is the second leading cause of lung cancer.

5. Radon can even affect water supplies, as elevated radon levels can occur in private water supplies.

6. Ventilation van prevent Radon in your home. 

How to reduce Radon

If you find out that your home contains high levels of radon gas, don't panic! There are simple solutions to reduce the amount of radon, and keep you and your family safe.

Some simple actions such as sealing around loft-hatches, sealing large openings in floors and extra ventilation do not reduce radon levels on their own. When combined with other effective measures, they can improve the reduction of radon levels. Completely sealing floors is difficult and can cause rot in wooden floors. The diagram below is intended as a guide. The Environmental Health Department of your local council may be able to offer advice. For levels in excess of 1000 Bq m-3 you may wish to contact PHE for advice.

Positive ventilation brings fresh air into a home, and dilutes the radon. The flow of air and radon from the ground may also be reduced. A positive ventilation system can be effective in homes with radon levels up to and around 500 Bq m-3.

A typical system has a fan in the roof-space connected to a vent in the ceiling. There are units for properties, such as flats, without a roof space.

Installation is quick and simple; the units are normally supplied with a fitting kit. A vent is fitted centrally in the ceiling, normally in a hallway or stairwell. The vent is connected by a flexible duct to the main unit which is supported by the ceiling joists or the rafters in the roof space.

The fans fitted in many units use similar amounts of electricity to an energy efficient light bulb. The systems improve air quality and may also reduce condensation.

At Envirovent, we offer a range of ventilation systems for your whole house, which improve your air quality and effectively deal with radon. Contact your local ventilation specialist to test your home for radon gas and find out if you are living in a radon affected area.