09/26/2012
"The most important known environmental carcinogen, after s***f smoke, radon gas is. No looks, no taste, no eye irritation or headache occurs we can alert you of their presence and accumulates in our homes, in indoors, in the air we breathe.
While they are regulated and controlled the daily half a kilo of food we eat or just over two liters of water we had in total, none of this happens with more than 25 kilos daily air we breathe inside buildings corresponding where we work, live or sleep.
RADON-222. Where does radon and more specifically its isotope, radon-222?. In the composition of the earth crust one participant is uranium-238 which, in the natural radioactive series, becomes radium-226, which in turn may become radon-222 that, by itself, and by their decay products of short life, provides a certain amount of radiation. Thus, the radon gas is produced in a natural way, in small quantities, not only on the ground, but even in construction materials themselves. Go through emanation into the atmosphere, where it can be inhaled at concentrations are higher logically indoors and inside homes than outside, where it is diluted so much that still constitutes a danger.
Also as groundwater seep through the soil and rocks, another possibility of contamination is to dissolve them a portion of radon gas. Radon does not seem to be a big threat if ingested with water, but in the lungs, ie, when issued from the water into the air and inhaled by the airways. In any case, under normal conditions, the half dose a person receives annually by inhalation of radon decay products reaches the amount of 1 millisievert (mSv), ie equal to the half of all radiation received including those caused by human activities: nuclear explosions, instruments, devices, displays, medical uses, and so on.
Clearly established a close relationship between the inhalation of radon and lung cancer incidence. It has also been shown that in smokers is greatly increased susceptibility to respect, so that, in them, the risk of lung cancer induced by radon is multiplied by a factor of ten compared to non-smokers. Even this risk is also significantly increased in passive smokers.
HAZARDS. This should not lead to the conclusion that our homes or workplaces are extremely dangerous. Specifically, the concentration of radon in a building is a reflection of uranium and radium content of the soil on which it stands, but also of the physicochemical properties of soil: porosity or character arcósico (with contents above) or clay (content lower). Also greatly influence the materials used in the construction, particularly in the foundation as well as the presence of gas leakage pathways such as cracks in the floor or walls. Obviously gas accumulation depends so very important to the existence or not of adequate ventilation.
What is the situation in our country? : We know something. The Environmental Research Center, with the support or collaboration of material and human Group Radiation Physics at the Autonomous University (Barcelona), the Nuclear Safety Council and the National Radioactive Waste Company, has made some measurement campaigns in the cities of Madrid and Barcelona. To have used it for two years over two thousand special radon dosimeters, detectors equipped with polycarbonate bisfemol-A. These dosimeters were placed in a total of 661 homes, often more than one per household, whose characteristics were diverse: houses, blocks, at different heights, and so on.
LEVELS. Although dosimeters measured radon concentrations, the values can be converted to the equivalent annual radiation, remember that with the global average is about 1 mSv. The relevant international organizations recommend corrective decisions of the situation in newly built dwellings whose radiation exceeding 5 mSv / year or if the former exceed 10 mSv. In Madrid, above these alarm values were respectively 3% and 2% of homes tested, with the overall average of 1.6 mSv, while in Barcelona these percentages, in each case, were always less than 0.5%, with an overall average of 0.9 mSv / year. Obviously, the houses, low-rise, they corresponded higher values surpassing its average twice the rate corresponding to the block. As they descended in height, radon concentrations were increasing, so that while 100% of the basement exceeded the reference value of 1 mSv, and the percentage was less than 50% in the first plants. In Madrid the highest values in connection with Barcelona, due to its soil arcósico, richer in natural radioactivity than sedimentary Barcelona.
The data obtained confirm the interest of such studies are performed or similar in the various Spanish regions, in order to identify the most dangerous areas to take corrective measures are feasible and relatively inexpensive. They consist, with adequate ventilation, to repair existing defects that facilitate the release of radon gas: cracks in the soil, wall-floor joints or walls, eliminating gaps around pipes, or reduced Cam walls. Moreover, such studies would be very useful that were carried out, in advance, before undertaking the initiation of large developments, especially those that predominate in low-rise buildings and houses.
However, although very small number of investigations into such cases in Spain, it seems that, for now, the values found for radon concentrations follow a pattern similar to the average for the rest of the world. Determinations should be generalized to subsequently detect and correct those cases in which the accumulation of radon constitute a health hazard."
