Le Radon en Profondeur : Conseils Utiles et Articles Spécialisés
A short history of radioactivity.
In 1896 Henri Becquerel discovered the spontaneous emission of a new type of radiation from a sample of uranium, uranium radiation. This radiation is ionizing, i.e. it produces electrical charges when passing through the air. The unit for measuring radioactivity in Canada is the becquerel per cubic meter (bq/m3). 1 bq/m3 is equivalent to one disintegration per second. In the United States the unit of measurement is the picocurie per liter (pCi/L)1 pCi/L = 37 bq/m3. Radon was officially discovered in1900 by Friedrich Ernst Dorn who named it “emanation.”. In 1910 radon was formally identified as a new element in the periodic table of elements, a radioactive noble gas Rn 222. Radon comes from the natural breakdown of uranium and radium present in the earth's crust. Radon decomposing creates the formation of Radon Decomposition Products, RDPs, such as Polonium 218 and Lead 214, which are solid elements. Radon is a heavy gas that will tend to accumulate in the basement of your building. In the open air, radon is present in small quantities and does not represent a danger and is around 10 bq/m3 however in our homes it can accumulate in large quantities in basements and represents a danger for occupant’s health.
What are the different types of radon detectors?
1- Open activated carbon or diffusion barrier 2- Charcoal Liquid Scintillation 3- Alpha Trace Detector 4- With ionization chamber and electret 5- Numeric 6- Continuous measurement At Gaz radon Québec we recommend that you use the detector with ionization chamber and electret to obtain an accurate and rapid reporting of results.
There are several advantages to using our detectors with ionization and electret chambers!
Our detectors can be used for short or long-term measurements with an accuracy rate varying from 8 to 15% depending on the OMF. In comparison, alpha trace dosimeters have an efficiency varying from 10 to 25% always depending on the OMF. The time required for a measurement can vary from as little as 2 days to 1 year. We provide a dosimeter configured according to the customer's needs with an ionization chamber and the type of electret appropriate for the duration of the test. Deployment is quick and easy to do yourself. Results are available the day after the dosimeter is returned to our lab.
How does a detector with ionization chamber and electret work?
Radon decays into RDP, Radon Decomposition Product, thereby emitting alpha and gamma radiation. The RDPs from the radon inside the chamber continue to decay, emitting alpha, beta, and gamma radiation. All alpha and beta radiation as well as most gamma radiation cause ionization of the air in the chamber. The electrons emitted during the ionization process accumulate on the surface of the electret, thereby reducing its positive voltage. The resulting voltage change is calibrated to the average radon concentration over the duration of the exposure.
What influences radon infiltration and its concentration?
1- The nature of the radon source and its strength 2- Radon transport 3- Depressurization forces 4- Emission levels 5- The source of drinking water such as a well 6- The ventilation of the building 7- Weather conditions
How is radon harmful and can cause cancer?
Radon does not cause itchy skin, chronic cough, emphysema. Radon is a gas and the decay products of radon RDPs are fine solid particles of known human carcinogens. The energy absorbed, dose, particularly that carried by the alpha particles coming from the PDRs, can damage living tissues, in particular the lungs. The total effective dose transported comes from 97% of RDPs (Polonium 218 and Lead 214) and about 3% from radon. Note that the RDPs produced by radon are solids. When you inhale and exhale a significant fraction of the PDR is not evacuated and the effect accumulates with each breath. The radiation affects the DNA of the lungs causing cancer.