Multisensory virtual nature immersion is emerging as a tool for supporting mental health management. In this study, we evaluate the effectiveness of two types of multisensory immersion systems for patients diagnosed with Post Traumatic Stress Disorder: (1) a PORTABLE system, which delivers olfactory stimulation directly through a head-mounted display (HMD), and (2) a POD system, in which participants are seated in a multisensory pod that augments HMD audio-visual content with synchronized olfactory cues and haptic feedback (wind and vibration). Beyond comparing the two modalities, this work focuses on how neural activity changes throughout the experience. Specifically, we analyze electroencephalography (EEG) responses in relation to participants’ subjective affective ratings, clinical questionnaires, and cognitive faculties.