From pollen to diesel fumes, the air we breathe is filled with potential allergy triggers that can irritate the nose, throat, eyes and skin. POLLEN, the most common airborne allergen, is a fine, coarse powder responsible for plant reproduction. It is likely to set off allergy attacks from early spring through late fall. Symptoms include sneezing, itching, congestion and post-nasal drip. MOLD is another airborne allergen that causes many people a lot of discomfort. About 20 percent of people who suffer from airborne allergies are also affected by mold. Mold can grow in any damp environment, from a bathroom or basement or around a garden. Symptoms include itchy eyes and trouble breathing. DUST MITE droppings are a common airborne allergen found floating around your home. They are often a problem in pillows and bedding--anywhere that we shed skin cells. PETS also are a significant source of airborne allergens. Their irritating dander is mixture of small particles of fur and dandruff-like skin scales. Cat allergies, however, are caused by a protein in their saliva. Because cats are constantly licking themselves, saliva latches to their fur, which floats into the air and toward your nose and throat. Before you know it, your nose is runny and stuffy at the same time, while your throat and eyes become itchy. In addition to these "natural" allergens, many chemicals can cause allergies.Nitrogen dioxide and sulfur dioxide found in smog and cigarette smoke, can cause nasal hyper-responsiveness resulting in extreme sensitivity. Diesel fumes can weaken the delicate nasal lining, allowing irritants to more easily trigger an attack. Even air conditioning, which is supposed to help clear the air, can produce allergy-laden residue that contains pollen along with a number of other allergens. To avoid airborne allergens as much as possible, keep pets out of the bedroom, get dust-mite protective mattress and pillow covers, wash your hair before going to bed to remove pollen that's accumulated during the day, and stay in filtered air indoors during high-pollen days. For more information on managing your allergies, watch the other videos in this series.