Symptoms
Chronic exposure to radon is the second leading cause of lung cancer after smoking. The cancer does not develop immediately, but after years or decades. It is estimated that 200 to 300 people die each year in many countries from lung cancer caused by radon. In Germany, the number of victims per year is expected to be 2000, in the USA up to 20,000. The combination of smoking and radon is considered particularly dangerous.
Causes
Radon (Rn) is a naturally occurring noble gas with no odor, taste, or color that occurs in the air we breathe. It is formed as a decay product of uranium-238, which is found in soil and rock. Radon exists in the form of various radioactive isotopes that emit alpha radiation as they decay. One of them is radon-222 with a half-life of 3.8 days. The radon progenies, e.g. polonium, are also radioactive. They can be deposited as solids in the respiratory tract and are therefore particularly dangerous. It is this radiation which, after inhalation of radon gas or its derivatives, can lead to DNA damage to the epithelial cells of the lungs and eventually, after years, to cancer. According to the WHO, radon belongs to the same class of carcinogens as cigarette smoke, benzene and asbestos. Radon enters houses mainly from underground via air currents and accumulates there. The highest levels are measured in the basement, with levels decreasing progressively on upper floors. Other less common sources are contaminated water and building materials that emit radon. In many countries, the highest radon levels are measured in the Alps and the Jura Mountains. However, with the introduction of the new WHO limits, almost all regions are considered risk areas.
Measurement
Radon concentration can be determined with a dosimeter. Each house must be assessed individually, because a different siutation can already be found on the neighboring property. The Federal Office of Public Health publishes a list of recognized measuring stations where dosimeters can be obtained. According to the WHO, the limit value is currently 100 Bq/m
3
, in exceptions at 300 Bq/m
3
. In many countries, higher values of 400-1000 Bq/m used to apply.
3
.
Prevention
Radon enters buildings through cracks, joints, openings and open basement floors. With appropriate structural measures in new buildings or building renovation in old buildings, radon levels can be reduced below the limit.