Implementation of activities under the National Strategy and National Plan

Free of charge detectors

The NCRRP provides free-of-charge detectors for the assessment of the corrective actions' effectiveness in reducing radon levels in buildings.

European Atlas of Natural Radiation

The data on the average annual volume activity of radon for dwellings from the studies under the National Plan are provided for inclusion in the European radon map.

Ways of measuring radon

The only way to know what the radon concentration in the building is and whether you are at risk is to measure it.


Photos from events held in the implementation of National Radon Plans

Radon is a colorless noble gas, odorless, which makes it completely undetectable to the human senses. Radon is radioactive and is formed by the radioactive decay of radium, which is a decay product of uranium in soil, rocks and water, from where it enters the air. Radon emits alpha particles and as a result decays into several solid radioactive products. Being an inert gas, radon is inhaled and exhaled without actually being retained in the body. However, its daughter products (Po-218, Pb-214, Bi-214), which are also radioactive, are solids deposited on the walls of the respiratory tract. The lung absorbs alpha particles emitted by the progeny of radon. The resulting dose increases the risk of lung cancer.

Radon quickly breaks down into radioactive particles that are deposited on airborne particles, inhaled, and thus deposited in the respiratory tract and lungs.

The World Health Organization recognizes radon as one of the leading causes of lung cancer.

Radon is everywhere; formed from uranium in all rocks and soils. Radon is a natural source of ionizing radiation. About 50% of the content of the earth's natural radiation background is due to radon.

Human exposure to radon is mostly indoors.

The only way to know what the indoor radon concentration and if and whether you are at risk is to measure it with detectors.

The amount of radon (concentration) is measured in becquerels per cubic meter of air (Bq/m3). The reference level of the average annual volume activity of radon (radon concentration) in air in residential and public buildings according to the Bulgarian legislation is 300 Bq/m3.

The reference level is not a strict boundary between dangerous and safe, but an indication for taking measures to reduce the radon value in the building.

Some common ways of reducing radon levels in existing buildings include:

  • increasing under-floor ventilation;
  • installing a radon sump system in the basement or under a solid floor;
  • avoiding the passage of radon from the basement into living spaces;
  • sealing floors and walls; and
  • improving the ventilation of the building, especially in the context of energy conservation.

Passive systems of mitigation can reduce indoor radon levels by more than 50%. The reduction methods are established in the Ordinance of the Ministry of Regional Development and Public Works.