EngineerHub.orgConvert a measured radon concentration to an estimated dose
Enter the average indoor radon level and occupancy. The calculator applies an equilibrium factor and the conventional UNSCEAR dose conversion coefficient.
Exposure inputs
Estimated dose
Background
Open a section to understand the model, equations and limitations.
E = C × F × t × DCF
C is radon concentration, F the equilibrium factor, t occupancy time and DCF the dose conversion coefficient. The result is a screening estimate of effective dose from radon progeny.
Radon varies between buildings and can vary seasonally. A national or regional map cannot replace a measurement in the occupied room. Long-term measurements are normally more representative than short snapshots.
Effective dose is a radiation-protection quantity, not a direct personal cancer prediction. Smoking and radon interact strongly in lung-cancer risk, but this page deliberately keeps dose calculation separate from individual medical risk.
The default equilibrium factor of 0.4 and dose coefficient of 9 nSv/(Bq·h/m³) follow the conventional UNSCEAR assessment approach. See UNSCEAR 2019 Annex B and the 2024 public-exposure assessment.
Reference level: WHO recommends that countries set an annual-average residential radon reference level of 100 Bq/m³ where practicable; if that cannot be achieved under national conditions, the selected level should not exceed 300 Bq/m³. This is a level for optimizing remedial action—not a boundary between “safe” and “dangerous.” National legal values may differ.
Dose comparison: the page also compares the calculated dose with approximately 3 mSv/year, the current UNSCEAR estimate of average worldwide exposure from natural sources. That global average is descriptive, not a dose limit.
Frequently Asked Questions
Practical questions about interpretation and use.
No. It estimates effective dose using the conventional UNSCEAR equilibrium-factor method. It does not predict an individual probability of disease.
Radon gas itself is not the main dose contributor. The equilibrium factor represents the relationship between radon concentration and the concentration of its short-lived progeny.
A short test can be entered, but annual dose is best estimated from a representative long-term average because indoor radon varies with weather, ventilation and season.
The default is the conventional UNSCEAR coefficient of 9 nSv per Bq·h/m³ of equilibrium-equivalent radon concentration.