Radon Individual Dose Calculator - HELP
(last updated 20 Sep 2012)
This calculator performs radiation dose calculations for individuals exposed to Radon-222 and its decay products.
The calculator only determines doses to exposed individuals. For collective dose calculations, see the Nuclear Fuel Population Health Risk Calculator.
The calculator only determines dose rates for situations, where the activity concentration or annual exposure of radon and/or its progeny is known. Otherwise, the Uranium Mine and Mill Resident Individual Dose Calculator, or some more sophisticated software has to be used (see Dose calculation software).
The parameters used for the calculation can be set in the Radon-222 Input Data table. These parameters show reasonable initial values which can be modified as needed. There are no other hidden parameters used in the calculation. Any assumptions made for the calculations are described on this page.
- select appropriate unit for
- radon-222 concentration in air: Bq/m3, pCi/l
1 pCi/l is equivalent to 37 Bq/m3
- annual radon-222 exposure: MBqh/(m3a)
- radon-222 progeny concentration in air: Bq/m3 EEC, pCi/l EEC, ÁJ/m3, MeV/cm3, WL
EEC stands for Equilibrium Equivalent Concentration,
J (Joule) and eV (electron-Volt) are measures for the potential alpha decay energy of short-lived radon daughters (1 eV = 1.602 · 10-19 J),
1 WL (Working Level) is defined as any combination of short-lived radon daughters in 1 liter of air with the potential of emitting 1.3 · 105 MeV of alpha particle energy during decay to lead-210. 1 WL is equivalent to 130 MeV/cm3, 20.83 ÁJ/m3, 101.3 pCi/l or 3746 Bq/m3 of radon-222 in equilibrium with its short-lived decay products (see also Unit Converter)
- annual radon-222 progeny exposure: WLM/year, mJh/(m3a), MBqh/(m3a) EEC
1 WLM (Working Level Month) corresponds to an exposure of 1 WL for 170 hours. (see also Unit Converter)
- Equilibrium Factor (used for units Bq/m3, pCi/l, and MBqh/(m3a))
- fraction of potential alpha decay energy of the short-lived radon decay products, compared to secular equilibrium. The equilibrium factor is defined as:
F = (0.106 cPo-218 + 0.514 cPb-214 + 0.380 cBi-214) / cRn-222
where cx stands for the activity concentration of the nuclide x.
Typical values are 0.4 for indoors or work, and 0.6 for outdoors.
- Risk Factor [1/WLM]
- Fatal cancer risk per WLM.
ICRP65(1994) used a value of 0.000283 per WLM, corresponding to 8 x 10-5 per mJh/m3. On Nov. 16, 2009, ICRP recommended "a detriment-adjusted nominal risk coefficient for a population of all ages of 8 x 10-10 per Bq h m-3 for exposure to radon-222 gas in equilibrium with its progeny (i.e. 5 x 10-4 WLM-1)" (view details).
U.S. EPA (2003) uses a value of 0.000538 per WLM for radon in homes for the U.S. population, based on BEIR VI (view details).
- Occupancy and Dose Factor
- determines the time in a year a person is exposed at the given rate. For workplace situations, the time is entered in hours per year; for other situations, it can be entered in percentage of total time, or continuous exposure can be selected.
The number of years entered allows for cumulative dose calculation.
While the dose factors used in ICRP65 were 5 mSv/WLM for workers and 4 mSv/WLM for the public, a new assessment has determined these as 12 and 9 mSv/WLM, respectively (J.W. Marsh et al: Dose conversion factors for radon, in: Health Physics Vol. 99, No. 4 (Oct. 2010), p. 511-516).