RADON gas. What is it?

Radon (Rn) is the colorless, odorless and tasteless radioactive gas that rises from the surface of the earth from geological uranium (U) formations all over the world, so we can discover a lot of houses and buildings, not only in Italy and in Sardinia, having a dangerous concentration of Rn.

Indoor radon gas can be tested in buildings because of its movement from inside the earth through cracks in the foundation, through drains and sump pumps, through water from wells and even directly through solid concrete walls, especially in volcanic areas.

Uranium is a heavy element discovered in 1789; it’s radioactive and it’s the father of Radon gas.

Radon gas has been discovered in 1900 by the German physicist Friedrich Ernst Dorn.

The atomic number of Radon gas is 86 (Z = 86).

There are three types of radiation: Alpha, Beta or Gamma rays.

The radiation of radioactive Radon gas (Rn-222) is due to an emission of an Alpha particle: it’s a nucleus of Helium (2 protons and two neutrons) that moves from Radon-222 to the environment, traveling at nearly the speed of light for several feet (1 foot = 0,3048 m).

The time it takes for radioactive element to break down and to release its (alpha) radiation is measured as its half-life (t1/2): it’s the amount of time required for half of its atoms to decay and to transform it into another element or isotope.

Uranium-238 (U-238) has a half-life of 4.5 billion years and its decay chain is very long. The first ring of the chain is the decay of U-238 (A = 238, where A is the mass number) into Thorium-234 (A = 238 – 4). As a matter of fact Uranium loses 2 protons and 2 neutrons (1 alpha particle or a nucleus of He) and produces a new element known as Th-234, that is radioactive, with a half-life of 24 days.

Radium-226 (Ra-226) is another step in the complex decay chain of U-238. When an isotope of Ra-226 decays, it shoots an alpha particle and finally we have an isotope of Radon-222 (A = 222 = 226 – 4), with a half-life of more than 3 days (t1/2 = 3,8 days).

The decay products of Radon, like Polonium-218 (Po-218) are all radioactive. At the end of the decay chain [Polonium-218 (t1/2 = 3 min) -> Lead -214 (t1/2 = 27 min) -> Bismuth-214 (t1/2 = 19,7 min) -> Polonium-214 (t1/2 = 1,6 x 10-4 s) -> Lead -210 (t1/2 = 19,4 yr)] we have a nonradioactive isotope: lead-206 (Pb-206).

Lead, bismuth and polonium are heavy metals and they are chemically active; the particles of these metals quickly attach themselves to dust and smoke in the air, clothing, furniture and walls.

Every year, all over the world, a lot of people die (20,000 per year in the USA) because they breathe and inhale the isotope of Rn-222 and its radioactive decay products. When these radioactive products are inhaled they continue to decay emitting α, β and γ rays in the lungs and upper respiratory tract. In fact WHO has classified Radon gas responsible for lung cancer; Rn-222 is the first cause of lung cancer in nonsmokers.

The WHOs value limit for indoor Radon gas is 100 Bq/m3.

RADON FREE - Radiation Monitoring (logo 3) BMPRADON FREE - Radiation Monitoring (logo3)It’s a relatively easy matter to test a home, a school or a workplace for concentrations of radon activity; in Sardinia ®Radon Free – Radiation Monitoring (www.radon-free.eu) is testing for Rn-222 all the schools in Cagliari, the first town (more than 100,000 citizens) wich is the big Island (24,000 km2) in the center of the Mediterranean Sea.

Rn concentrations are, often, higher than 100 Bq/m3, so a lot of children are exposed every day to a lot of dangerous radiations!

Dr. Andrea Alessandro Muntoni

(andreaalessandro@muntoni.it)

Bibliography

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  2. A. A. Muntoni, Ambiente e sicurezza – Effetti dell’incidente nucleare sull’importazione di alimenti dal Giappone, in “La Gazzetta del Medio Campidano”, anno XIII, 25 aprile 2011, pag. 29, Media Tre Editrice, Guspini (VS)
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  10. A. A. Muntoni, E. Pascariello (2013), Ambiente e sicurezza. RADON. Aspetti biologici legati all’esposizione al gas radioattivo, in “LA GAZZETTA DEL MEDIO CAMPIDANO”, anno XVI, n. 5, 1 marzo, pag. 24, Media Tre Editrice, Guspini (VS)
  11. A. A. Muntoni, RADON. Quali rischi?, in “eco IDEARE – Periodico culturale di informazione sullo sviluppo sostenibile”, n. 22, marzo 2014, pagg. 26 – 29, Brand Evolution, Milano
  12. C. Colombi, Quanto gas radon nelle scuole di Cagliari? Monitoraggio da ottobre all’aprile del 2014, in SARDINEWS, n. 5, anno XIV, maggio 2013, pag. 15, Cagliari
  13. M. Lafavore, Radon. The invisible threat, Rodale Press, Emmaus, Pennsylvania, 1987
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