From Eq. (15), the value of Y'(k); which is the time series of radon concentration related only to the environmental parameters, could be estimate by a modified Adaline structure from the measured value Y(k) and Xr1(k),Xr2(k)...Xm(k); as shown in Fig. 1(b). The values of r1;r2;y;rm are obtained from some investigation. Each value ofr1;r2;y;rm that conclude the best fit between estimated and measured time series for soil gas radon during normal data, is considered as the best values for them