Why Does Pollen Make You Sneeze?

It was a gorgeous, breezy evening for Edina soccer and the kids had a great time running up and down the fields behind , but as we climbed into the minivan I was miserable. Not only were my eyes red, but my nose was running like a faucet. 

Hay fever affects one in five Americans, according to the Mayo Clinic website.  It is also known as allergic rhinitis and causes symptoms similar to those of the common cold. However, hay fever is not caused by a cold virus, but can be triggered by pollen, dust mites or animal dander.

Pollen is a fine dust produced by plants. It consists of a few reproductive cells covered with a large number of non-reproductive cells forming a protective “coat” around them. When a grain of pollen lands on a compatible flower, it produces a pollen tube and allows the reproductive cell in the pollen to exchange genetic information with that plant.

Some pollen, like ragweed pollen, is very light and floats easily through the air. Unfortunately, when some individuals get air-born pollen in their nose or eyes, they can have an atopic—or allergic—reaction.

The word “atopy” refers to localized allergic reactions. Hay fever is an atopic reaction, since it occurs at the site where the allergen (in this case pollen) enters the body. Since air-born pollen can only enter your body through your nose and eyes and mouth, this is where symptoms occur.

The first time your body is exposed to pollen, like ragweed pollen, your immune system sees it as a foreign invader and quickly goes to work making antibodies to attach to the pollen particles. These antibodies gather on the surface of special white blood cells called mast cells.

From that time on, your body keeps a number of these antibody-coated mast cells on guard for future pollen “attacks.” Scientists say these mast cells are “sensitized.”

If you encounter the pollen for a second time, your body reacts quickly. When it binds to the antibodies on the mast cells, the pollen causes a process called “degranulation” to occur. Chemicals called histamines and leukotrienes are released from the cell and kick your allergic reaction into high gear as they cause an increase in mucus secretion (runny nose), capillary dilation (sinus pressure), itching and other allergic responses.

Ironically, pollen is relatively harmless and it is our own immune response that causes us to suffer. It is not well understood why some individuals have allergies while others do not, but there seems to be a genetic component to some people's hay fever.

Antihistimines, like Zyrtec, work by inactivating the histamines your mast cells are releasing. Anti-leukotrienes, like Singulair, are often used to prevent airway swelling involved in asthma, which can be allergy-related.  

Individuals with hay fever can take some simple steps during allergy season to avoid severe attacks. These include running air conditioning or HEPA filters and keeping windows closed, wearing a mask when mowing, washing hair daily, keeping pets out of bedrooms (pollen rides in on fur) and staying indoors on windy days or days with high pollen counts.

To check the four-day allergy forcast here in Edina—or anywhere else in the United States—you can go to pollen.com.