Radiation levels expected at the surface of Mars are known to have an impact on life form as well as biological and organic materials. Therefore the ionizing radiation must be studied in order to evaluate the potential organic preservation on Mars. MarsREC (Keating et al., 2005) and dMEREM (Gonçalves et al., 2009) are ionizing radiation environment characterization models based on GEANT4 (Agostinelli et al., 2003) Monte Carlo applications developed for the European Space Agency. Enabling the interface with geophysical databases, these models allow the evaluation of Martian radiation environment as a function of climatological and geological variables. This work defines critical geophysical parameters associated with geological evolution and assesses their impact in terms of radiation environment. Results show that the erosion of the Martian atmosphere and the regolith, due to the LHB era, led to an important increase of the radiation environment, consequently radiation hazard, and led to the degradation of habitability conditions at the surface of Mars.