Characterisation of the role of an active environment of use in an industrial Environmental Stress Crack Resistance (ESCR) test has been carried out during the tensile deformation of polyethylene samples. We intended to map the presence of the active environment within the material using Raman and infrared spectroscopy. We found Raman not suitable for the detection of this environment inside the sample while by IR the environment seemed to be predominantly present within the transition fronts of the material. A stress-induced environment diffusion mechanism is suggested. By scanning electron microscopy (SEM) differences in the deformation process between drawing in air or in detergent became apparent. These results suggest that the environment penetrates into the sample during the necking process, stabilising crazing. At the molecular level it is likely that chain slip and unravelling of molecular disentanglements are facilitated. All these observations may also be operative during the ESC phenomenon as samples are subjected to stress, resulting in crazing.