A user could walk near a river in the VR environment and not only hear the sound of rushing water but also smell wet grass. Or if they wandered into a forested area, they would smell the fresh scent of pine. This is accomplished by using hitboxes, which are invisible shapes in the VR environment that activate when the avatar collides with them.

— Read more in Stop And Smell The Roses — From Outer Space: Researchers at Texas A&M are looking at how multisensory virtual reality can support astronauts during future long-duration missions at Texas A&M Today.