What is Pollen? What is Pollen?
Academy of Asthma, Allergy and Immunology

What is Pollen?

If you are allergic to plants in your area, you may be interested in learning more about pollen. Many types of pollen, especially grasses, and molds are common to most plant zones in the United States . Additionally, other related plants can also trigger the same symptoms. Below are answers to some frequently asked questions.

Q: What is pollen?
A: Pollens are the tiny, egg-shaped male cells of flowering plants. Pollens from plants with bright flowers, such as roses, usually do not trigger allergies. These large, waxy pollens are carried from plant to plant by bees and other insects.

Q:What types of pollen trigger allergy symptoms?
A: Many trees, grasses and low-growing weeds have small, light, dry pollens that are well-suited for dissemination by wind currents. These are the pollens that trigger allergy symptoms. Seasonal allergic rhinitis in the early spring is often triggered by the pollens of such trees as oak, western red cedar, elm, birch, ash, hickory, poplar, sycamore, maple, cypress and walnut. In the late spring and early summer, pollinating grasses – including timothy, bermuda, orchard, sweet vernal, red top and some blue grasses – often trigger symptoms. Ragweed is the pollen most responsible for late summer and fall hay fever in North America.

Q: What is a pollen count?
A: Pollen counts measure the amount of airborne allergens present in the air. Counts are compiled by a variety of methods. Pollen counts are reported as grains per cubic meter of air. Certified aeroallergen counters at many universities, medical centers and clinics provide these counts on a volunteer basis.

Q: How do you acquire pollen counts?
A: The American Academy of Allergy, Asthma and Immunology has a network of pollen counters across the United States . Each counter works under the direction of an AAAAI member and must first pass an intensive certification course. Counters use air sampling equipment to capture air-borne pollens.

Q: Can weather affect a pollen count?
A: Weather can influence hay fever symptoms. Allergy symptoms are often minimal on days that are rainy, cloudy or windless, because pollen does not move about during these conditions. Hot, dry and windy weather signals greater pollen and mold distribution and therefore, increased allergy symptoms.

Q: Is the pollen season the same from year to year?
A: The beginning and ending times of tree, grass and weed pollen seasons are very similar from year to year in the same location. Intensity differs every year based on the previous year’s weather, current weather, and other environmental factors.