In some people, allergy-like symptoms can be triggered, not by a true "allergen" but by an "irritant." This condition is called vasomotor rhinitis and can be very similar to its cousin allergic rhinitis. Irritants can also trigger asthma-like symptoms as well.
Common irritants include:
While symptoms of vasomotor rhinitis and asthma can be treated with medicines, avoiding the irritant whenever possible is your best first line of defense.