Radon is a natural radioactive gas found in uranium-rich and permeable soils. Radon easily escapes from the ground into the air and accumulates in buildings. When inhaled, radioactive radon progenies settle in the lung and become a direct cause of lung cancer. Radon is the second leading cause of lung cancer after smoking and first source of exposure to natural radiation in general population. 

Every year 45 000 people die due to lung cancer related to radon exposure in Europe and North America

Radon is part of more general problem of Indoor air quality. Pollution in indoor air is estimated to be the cause of 2.7% of World’s global diseases Children are the most affected group. In some European countries up to 30% of families deal with home humidity problems, resulting in a 50% increase in the risk of respiratory distress and 13% of cases of childhood asthma.

The World Health Organization estimates that 4.3 million people die every year due to diseases related to poor air quality inside buildings

Radiation dosimetry in the field of health physics is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both to ingested or inhaled radioactive substances and to irradiation due an external source of radiation. The worldwide average background effective dose for a human being is about 3.5 mSv per year, mostly from cosmic radiation and natural isotopes in the Earth.

The largest single source of radiation exposure for the public is naturally occurring radon gas.