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February 2025 | ✓ Medically Reviewed by: Gary Falcetano, PA-C, AE-C
A licensed Physician Assistant with more than 25 years of diverse experience in emergency and disaster medicine, primary care, and allergy and immunology, Gary Falcetano is the U.S. Clinical Affairs Manager for Allergy in ImmunoDiagnostics at Thermo Fisher Scientific.
Spring allergy season might be the most hated time of year if you are part of the 26% of adults in the United States who suffer from seasonal allergies and the sneezing, watery eyes, and endless amount of tissues that likely go along with it.1 If you’re among that segment of the population, you may think all hope is lost and you just have to power through “pollen-palooza.” After all, you can’t stop grasses, trees, and weeds from pollinating.
But knowing how much pollen is in the air at any given time means you can make informed decisions about your daily activities to better avoid triggers. If pollen count is high on a Monday morning, for example, you can wait until the evening to get in your daily run.
You might be thinking, “OK that’s good to know, but how does one track pollen?” Glad you asked. Here are answers to six frequently asked questions about pollen count.
A pollen count tells us how much pollen is in the air at a certain time. It’s based on the measurement of pollen grains in a cubic meter of air over a specific period.2 The higher the pollen count, the greater the concentration of pollen in the air. That means people with seasonal allergies (also called "hay fever" or allergic rhinitis) have an increased chance of experiencing allergy symptoms.
If you have seasonal allergies and you see a high pollen count on a given day, you can take steps to limit your exposure and reduce your risk of symptoms flaring up. Keep your windows closed, for example, or maybe skip some planned yard work and move that task to another day when pollen counts are lower.
Pollen is the male fertilizing agent of flowering plants.3 Some plants have large pollen that is carried by bees and other insects.3 However, many trees, grasses, and weeds have small, dry pollen grains that are blown by the wind, and these are the pollens that can cause allergy symptoms.3
Trees typically produce pollen in spring. Some of the common culprits for spring allergies include birch trees, which grow throughout North America and produce pollen as early as January, and oak trees, which have many different species growing throughout the U.S. Cypress trees are another common allergic trigger, but these will produce pollen up to seven months out of the year.
Grasses are found everywhere, and they typically produce pollen in spring and summer. Numerous grass species cause allergic reactions, such as ryegrass, which is found in lawns, roadsides, and even as agricultural feed. Timothy grass is another common trigger — up to 90% of people with a grass pollen allergy are sensitized to Timothy grass.4
Weeds are just plants growing where you don’t want them, but many of these plants pollinate in summer and fall. One of the worst offenders is common ragweed, which affects up to 15% of the population.4 This plant produces large amounts of pollen, particularly in late summer.
Pollen counts are generally taken with an air-sampling device. The device uses sticky rods that test the air on a regular basis. Every 24 hours or so, these rods are then examined for the number of pollen grains covering the rod. The count is converted into units of grains per cubic meter of air. Fortunately, these measurements are eventually calculated into an amount that makes sense to the general public: low, moderate, and high.
There are a few tools that provide timely information that allows you to consistently monitor pollen levels, so you can ultimately better manage your symptoms. One of them is pollen.com, which provides daily allergy forecasts that show the upcoming airborne allergen conditions in your local environment. Simply visit the website and enter your zip code to get a clear picture of the allergy and pollen forecast in your area.
Pollen levels vary depending on the location and season, and they're directly connected to weather conditions. Warm, dry, and windy conditions have high pollen levels, while rainy and/or cool weather dramatically drops pollen levels. The spring season is typically when pollen levels are highest, as grasses and trees are blooming in full force. Recent studies have found that midday is the worst time for a high pollen count, while early morning has the lowest.5 It is important to note that many plants pollinate year-round, so checking pollen counts every day throughout the year is recommended.
It depends on which type of pollen you're counting. Remember, these numbers are the number of pollen grains per cubic meter of air:6
While there’s nothing you can really do to prevent every microscopic speck of pollen from entering your personal space, checking pollen counts daily and knowing what to do with that information can help mitigate symptoms —and potentially reduce your tissue budget. Learn more about pollen allergies.
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