It s the same with allergies. Allergies are not watery eyes and stuffed-up noses, but reactions to irritants. Something foreign is triggering the body s cleaning responses. It s like walking behind a smoky bus when it starts up. That s an allergic response.
Humans are allergic to bus exhaust.
The eyes water to cleanse the eyes, and the coughing reflex kicks in to forcibly expel the toxic fumes before they get inhaled. It happens in an instant. Tolerance is a big problem. That means when we get used to an irritant, the body gives upon trying to expel it. Consider your average bus mechanic.