Author: Marc Alassane Touré
Radon, the Silent Killer
A title that may remind you of the ‘Scream’ movie saga. This time, the killer has been known for decades but still manages to sneak into your homes without any service to save you. If you don’t smoke, you don’t live with smokers either and end up with lung cancer, be almost sure that your assassin will be this colorless, odorless gas. Its name? Radon.
Quite terrifying news ? Now let’s get serious. Let’s put ourselves in the shoes of a Sherlock Holmes of modern times. Who is Radon? What is its origin? What are the real risks it poses? represents for the human being? How to prevent it from entering our homes? In short, today we will understand how to save lives.
Discovered in 1900 by Friedrich Ernest Dorn, Radon, with atomic number 86, is a noble, colorless, odorless and tasteless gas. It comes from uranium decay and is naturally present in soil or water (groundwater). Its half-life, which is the median life of a substance, is 3.8 days. All its isotopes being radioactive, it represents the first cause of natural radioactivity to which man can be exposed. Very dense, it would be about 8 times heavier than air at room temperature.
After its discovery in 1900, radon was long considered to be a non-harmful substance to our health. On the contrary, it was used in radiotherapy in the 1950s to cure certain cancers by eliminating cancer cells with limited radiation. In the 1960s, its harmful effects were discovered through numerous tests but also by noting a strong correlation between the increase in the rate of lung cancer and leukemia and the practice of mining in uranium mines.
But how does he get into our buildings nowadays? Radon can enter homes and other buildings through cracks in walls and floors, gaps around pipes, and other openings in the foundation. Once inside, radon can become trapped and build up to dangerous levels, particularly in areas with poor ventilation. In houses, it can accumulate in the basement or on the ground floor, particularly in areas with high levels of uranium in the soil.
How harmful is it to our health? Nowadays, the only known risk of radon is lung cancer. Indeed, it is the second cause of the latter behind tobacco with about 10% of global cases. In order to be more concrete in our explanations, it would be appropriate to detail the unit of measurement of the exposure. The concentration of radon activity is defined by the Becquerel per cubic meter. One Becquerel equals one radioactive disintegration per second. So that you understand, we can define that breathing constantly an air loaded with radon at 3000 bq/m3 corresponds to smoking daily a pack of 20 cigarettes.
We can therefore clearly state the levels of exhibitions currently encountered in Europe and more particularly in Switzerland in the various homes. At European level, the Radon concentration map is displayed as follows:
We note that the countries most affected are Hungary and Finland with rates of up to 300 bq/m3. Moreover, Switzerland is also a high-grade country with rates often higher than 100 bq/m3 visible on this map. It should be noted that since standards may vary from one country to another, certain ‘acceptable’ rates may be unacceptable in another country. In Switzerland, the risk of radon exposure is high in the mountainous cantons of Jura and Valais as this map shows:
Sanitation measures are essential in case the level would exceed 300 bq/m3 according to Swiss standards.
It will now be a matter of understanding what constructive aspects could be used to limit the effect of radon on residents.
The most trivial idea is the installation of watertight barriers between the ground and the house. It is called a radon barrier. A radon extraction system can be added under this barrier to remove it from the ground and reduce the hazard it represents. In addition to this, it will be necessary to plug all the openings around the passages of pipes, between the slab and the revetment of the ground as well as between the slab and the walls. In SIA 272, for example, a watertight concrete will be provided in this case. It must be XC2 class; for more details, you can refer to the SIA 262 or SIA 272.
After this potentially alarming discovery for some, fear probably haunts some of the readers. Well, a good start would be to determine the radon concentration in your home as soon as possible (for the most worried). To do that, two options are on the table. The first would be to buy a detector. But given the great disparity of concentration possible even within the same room, a large number of measurements should be made in the smallest corners of your room. The other possibility would be to contact a specialized service which will be responsible for carrying out all the measurements in a few hours with more sophisticated equipment.
And even if you realize that the concentration is above the thresholds allowed in your country, don’t worry! Technical means allow to evacuate the radon present in your home. After a concrete diagnosis, it could turn out that the air renewal in your rooms is insufficient. In this case, a simple improvement in ventilation could be enough to eradicate this invisible enemy. We could start with a recurring opening of the windows daily, increased maintenance of your ventilation system, and in an optimal way, provide for the installation of a pipe in the ground connected to a radon exhaust fan. This well-known system is called a soil depressurization system and does not require major changes in your home. In some popular cases, a radon reduction efficiency of 85% was achieved. You can see some explanations about this system right there :
And remember, in the end, the public enemy always ends up behind bars… or on the electric chair.
But if radon was long known as a silent killer, know that suicide is never so far in terms of air quality in our homes. Whether it’s the cigarette you smoke in a closed room, the gas you forget to put out for 10 minutes, or the multiple chemicals you let poison you, it is essential to pay attention to all these different elements and learn about ventilation systems adapted to our comfort… but especially to our health!