Tear gas causes irritation through well-defined chemical mechanisms, primarily by acting as an agonist that activates specific sensory neuronal ion channels such as TRPA1.
The retrieved papers consistently establish that tear gases (such as CN and CS) exert their irritant effects through specific biochemical pathways, notably by binding to and activating transient receptor potential (TRP) ion channels like TRPA1 on sensory nerves. All relevant empirical and review studies point to this precise chemical mechanism.