Abstract
Evaluation of radon concentration is a very difficult task and a very important issue, in relation to the protection of human health.
This is especially the case when there is an increase in concentration of radon on a deterministic basis, as is the case of nearby
phosphogypsum residues or geological characteristics. Radon gaseous that can be found in the environment occurs mainly from
natural radioactive decay chains. The gamma ray spectroscopy is a powerful tool in order to monitor the environmental
radioactivity. In this paper it have been measured and analyzed the radon concentration in a stainless steel vessel in order to
provide further evidence about the deterministic chaos character of smaller time series recoded data. We have found that the
fractal dimension of the radon concentration and recorded environmental parameters in the experimental vessel are strong
influenced by small variations of the initial conditions, that is proving the chaotic behavior of the measured parameters.