A problem of equilibrium between radon concentration and its progeny in a given environments has been presented. A value of equilibrium factor was investigated as a function of the following environmental parameters: humidity of the gas, aerosols, size and concentration, and radon concentration.
Correlation between the potential a energy for radon progeny and equilibrium factor was also described. In conclusion the definite program bas been proposed that allowed for practical interdependence between radon concentration, equilibrium factor and potential a-energy specified by the use of radiometer type RGR-40.