Pollen grains of many species areresponsible for some of the severe allergies and bronchial affliction in some people often lead to chronic respiratory disorders like asthma, bronchitis etc.
Related Theory
Allergic reactions are triggered when allergens interact the immune system, which produces an antibody that is specific to that antigen, i.e., IgE. These antibodies travel to mast cells that release histamine and other chemical mediators, which cause allergy symptoms to occur and serve to alert the immune system to local infection.