Radonkoncentration

Radonkoncentration, or radon concentration, is the amount of radon gas present in a given volume of air or soil gas, expressed as activity per unit volume. The standard unit is becquerels per cubic meter (Bq/m^3); in some contexts, picocuries per liter (pCi/L) are also used, particularly in the United States. Radon is a radioactive noble gas produced by the decay of uranium and thorium in rocks and soils.

Radon enters buildings mainly through the ground, entering through cracks in foundations, joints, and service penetrations. Its indoor concentration depends on geology and soil radon levels, building design, and ventilation. Weather and pressure differences can affect entry rates, while continuous ventilation and air exchange tend to dilute indoor radon.

Exposure to elevated radon concentration over long periods increases lung cancer risk, especially for smokers. Radon progeny, which attach to aerosols, deliver alpha radiation to lung tissue. Because the risk is dose-dependent, health agencies emphasize measurement and reduction in homes and workplaces with persistently high levels.

Measurement typically involves long-term detectors placed in living areas for three to twelve months to capture seasonal variations; short-term tests (two to seven days) are sometimes used for screening. Devices include charcoal canisters, alpha track detectors, and continuous radon monitors. Standards and action levels vary by country; the WHO recommends a reference level of 100 Bq/m^3, while many countries employ action levels between 100 and 300 Bq/m^3, or about 4 pCi/L in the United States (148 Bq/m^3).

Mitigation options include sub-slab depressurization, sealing of entry routes, and improving whole-house ventilation. In new construction, radon-resistant features such as gas-permeable layers and passive under-slab ventilation can reduce future concentrations. Regular monitoring is advised after mitigation to verify effectiveness.