This increase is partially attributable to the limited ventilation in most modern housing. Some have also suggested pollution may have a role. Recent studies however suggest this is probably not the case. In one study comparing the rates of allergic rhinitis in two German cites, no significant difference was found despite the significantly higher levels of pollution in the eastern city. The triggers responsible for allergic rhinitis may be classified as either seasonal or perennial.
Seasonal allergens are for the most part found outdoors.
Common seasonal allergens include tree, grass and weed pollens, and airborne molds. As one would suspect, these allergens depend very much on the geographic area. Signs and Symptoms People suffering from allergic rhinitis usually complain of itchy eyes, nose and palate, watery rhinorrhea, nasal obstruction, sneezing attacks that are often violent and prolonged, conjunctival irritation and lacrimation. The most important part of the physician's workup is taking a thorough history. A temporal relationship between allergen exposure and symptoms is almost diagnostic.