Sense of smell is our most rapid warning system

The ability to detect and react to the smell of a potential threat is a precondition of our and other mammals' survival. Using a novel technique, researchers have been able to study what happens in the brain when the central nervous system judges a smell to represent danger. The study indicates that negative smells associated with unpleasantness or unease are processed earlier than positive smells and trigger a physical avoidance response.

from Latest Science News -- ScienceDaily https://www.sciencedaily.com/releases/2021/10/211014100139.htm