The air is full of flying things. Luckily they're microscopic or you'd have to wear a suit of armor even in your own home. Unless you live in a sanitized glass bubble, it's impossible to completely avoid airborne allergens, such as pollen, dust mites, and pet dander. These identifiable flying objects cause allergic rhinitis, which simply means an inflammation of the nasal membranes. If you've heard of hay fever (and that includes everyone who has turned on a television or radio in the spring or summer, since there are so many commercials for antihistamines), then you know about allergic rhinitis: It's that drippy nose, itchy eyes and throat, and sneezing that's so familiar during pollen season.
While pollen is one of the most common triggers of allergic rhinitis, it is not the only one. Mold spores; dust-mite droppings; cockroach body parts; and animal dander can also prompt an allergic reaction. You can be allergic to only one or to several of these airborne particles.
The next few sections will help you understand the pollens, spores and pets that cause allergic rhinitis.