Between two heartbeats, between 8,000 and 10,000 atomic nuclei disintegrate in our body. Every hour, about 30,000 nuclei disappear in our lungs simply because of the presence of radioactive isotopes in the air we breathe. Due to the food we eat, about 15 million nuclei of Potassium-40 and about 7,000 of natural uranium disintegrate in our stomach and intestines. Smoking releases radioactive lead and polonium , which end up in the atmosphere and in our lungs: a pack a day means receiving 3 times more radiation than the average amount due to the deadly radon gas naturally present around us. Spending vacations at sea provides us with an additional supply of radioactivity: in a cubic meter of seawater, 10,000 atoms disintegrate per second. Replacing it with the mountains does not improve the situation much: in the Pyrenees or in the Picos de Europa we receive 3 times more radiation than on our favorite beach. To all this we must add the more than 200 million gamma rays from the ground and building materials that pass through us every hour, and the several hundred thousand secondary cosmic rays, a by-product of the interaction of radiation and subatomic particles emitted by black holes, active galaxies or supernova explosions with the atoms of the upper atmosphere. The astronauts, in the first space trips, verified the impact of these particles on their retinas, since the light flashes they produced prevented them from sleeping peacefully.
Of course, the real danger is radon gas . In closed areas such as buildings, mines, subway galleries, tunnels, etc., its concentration can be high due to the poor ventilation that exists: in caves in Tenerife and Lanzarote, values have been measured that exceed 5,000 disintegrations per second and per cubic meter . Let us remember that the WHO has given a value of 100 disintegrations per second per cubic meter as a reference annual average for all countries. For their part, the most common construction materials -wood, bricks and concrete- give off relatively little radon, although they have sometimes given us unpleasant surprises, especially those that come from ashes from thermal power plants or steel mills. In Sweden in the 1960s, it was discovered that the alum slates used for decades in the production of concrete for houses were “quite” radioactive.
The continuous production of radon reaches our homes through cracks and fissures in buildings. When the concentration of radium in the soil is higher, as occurs in some granitic formations, uranium-bearing or phosphate-rich soils, the value of the emission can be tens of times higher. This happened to Stanley Watras and his family in 1985. The house they lived in was located in an area with uranium-rich soil. Watras worked at the Limerick Nuclear Power Plant and one day, when he went to work, he triggered the plant’s alarm. Further investigation showed that the Watras’ house was built on land with a radon concentration nearly 2,000 times higher than normal US values. Breathing the air in the Wratas’ house was equivalent in chance of getting lung cancer, to smoke 135 packs of tobacco per day. People living in houses with concentrations one-tenth that of Watras are receiving annual exposures equivalent to those of people evacuated from nearby Chernobyl in 1986 after the nuclear power plant accident.
To all this we must add certain human activities that contribute to the production of this radioactive gas : the burning of natural gas and coal, the manufacture of fertilizers with phosphates (which have high concentrations of uranium) and the generation of slag from the treatment iron in blast furnaces. A typical 1,000 MW thermal power station consumes about 10,000 tons of coal (which contains uranium) daily, so its daily radiation emission is similar to that produced by two tons of Uranium-238.
Groundwater also carries radon – rivers and oceans have much lower concentrations. On average, the radioactivity of a liter of water due to the effect of radon is usually 4 disintegrations per second . But if that water comes from a well in land with a high uranium content, the activity is 5,000 times greater and in some cases it can be millions of times greater, as in some wells that supply the city of Helsinki – Finland is the European country which receives the highest dose from radon. The mineral water in Bad Gastein, Austria, is a million times more radioactive than public drinking water, and several decades ago visitors were encouraged to drink it and even stay in caves in the area, where they inhaled radon. According to measurements carried out in spas in our country, the situation is not that dangerous, but some have been found with values as high as 824 disintegrations per second per liter of Radio-226.
And in our houses? The real panic room is the bathroom . A study carried out in Finland showed that the concentrations present were three times higher than those in kitchens and 40 times higher than in the living room. For their part, Canadian scientists revealed that radon in bathroom air increased rapidly after a 10-minute warm shower. Once finished, it was necessary to allow more than an hour and a half to pass before the radiation returned to the initial levels.
