Question:  What can be done when the allergen is not avoidable or very difficult to avoid, as in the case of airborne pollens? (continued)
...needed frequently or continuously, desensitization to the allergen(s) (medically known as "allergen immunotherapy") may be necessary. This treatment, which is administered by allergy specialists, works by strengthening the immune system to overcome the allergic sensitivity long-term.

Question:  What is the relationship between allergy to airborne substances and respiratory infections, such as sinus infection and bronchitis?
Sensitivity to airborne allergens (such as tree, grass, and weed pollens, dust mite, mold and mildew, and indoor animals) may predispose to persistent and recurrent respiratory infections by keeping the membranes of the nose, throat, and bronchial tubes continually irritated and swollen, and therefore less resistant to infection.