Seasonal allergies affect more than 40 million Americans each year. Plant biologist Dr. Kristina Stinson of Harvard University explains how allergies affect the body, and why warmer weather could lead to longer, more severe allergy seasons. "Science Behind the News" is produced in partnership with the National Science Foundation.
Science Behind the News - Allergies
ANNE THOMPSON, Reporting: (from file):
It is a pretty sight, spring flowers and some trees already blooming in many parts of the country during this unusually warm winter. But it is not a happy sound.
ANNE THOMPSON, Reporting:
The sneezing. The runny nose. The watery eyes. Its allergy season. More than 40 million Americans are affected by seasonal allergies, and with the winter of 2012 on track to be 4 degrees higher than average, and the fourth warmest on record, the early budding trees and flowers mean allergy sufferers are on their way to a season of misery.
DR. KRISTINA STINSON (HARVARD UNIVERSITY): Temperature is one of the major cues that plants use for growing and for reproducing. So when you have a warmer spring, for example, or a warmer winter that leads to an earlier spring, a plant can start growing and reproducing at an earlier time than in colder years.
THOMPSON: Allergy season begins when temperature, weather conditions, and other factors allow for flowers to start budding, or trees to come out of dormancy and grow leaves.
From plants come pollen, a tiny, powdery substance they manufacture for reproductive purposes. But to some people, it's an allergen.
STINSON: An allergen can be anything in the environment that triggers this, the body's defense against a foreign substance.
THOMPSON: Doctor Kristina Stinson is an ecologist at the NSF-funded Harvard forest Long Term Ecological Research site in Petersham, Massachusetts. She studies the effect of regional climate conditions on plants like ragweed, one of the main pollen producers in the U.S.
STINSON: When pollen enters the body through the nose or the eyes, it is irritating, and in response to that, the body produces things like histamines and those are the things that cause a runny nose, or sneezing, and other kinds of allergy symptoms.
THOMPSON: This is how it happens: the allergen is detected by lymphocytes, a type of white blood cell. The lymphocytes mistakenly identify the allergen as something harmful and create antibodies to neutralize the allergens. The antibodies attach to the surface of mast cells and the next time the allergen approaches, they fight it with chemicals, such as histamine, which in turn triggers an inflammatory response.
STINSON: An allergy is really just a reaction to a foreign substance in the body. And so the sneezing and the itchy eyes and the runny nose and so forth is the way of just flushing that foreign substance out of the body. So a person with allergies isn't really sick, they just don't feel very good.
THOMPSON: The tendency to be affected by allergies can be attributed to heredity. If your parents are allergic to tree pollen or ragweed, chances are you'll be allergic as well. Aside from genetics, the environment plays a part.
STINSON: As you become exposed to more and more substances in the environment that are irritating, the more likely you are to have some kind of a reaction.
THOMPSON: Doctor Stinson warns that if global temperatures continue to rise, our future could be filled with longer and more severe allergy seasons.
STINSON: We're basically creating a greenhouse environment where the plants in nature are getting a jump start on what they normally would have as well. And if we're doing this for plants like poison ivy, plants like ragweed that are allergenic then to some extent we are creating an environment that's going to be less comfortable for ourselves.
THOMPSON: So with allergy season starting sooner and lasting longer, it's a good idea for allergy sufferers to get a handle on what causes their allergies so they can stop and smell the roses instead of sneezing on them.
Winter is coming ... later. And it's leaving ever earlier.
Across the United States, the year's first freeze has been arriving further and further into the calendar. That's according to more than a century of measurements from weather stations nationwide.
Allergy, Allergies, Seasons, Trees, Flowers, Grass, Ragweed, Temperature, Plants, Reproduction, Histamine, Sneeze, Lymphocytes, Allergen, Antibodies, Mast Cell, Pollen, Nose, Environment, Climate Change, Global Warming, Cue, Winter, Spring, Dormancy, Defense, Mechanism, Inflammatory, Foreign, Nature