Everything to know about pollen count

March 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.

A model two story home with a tree behind it that is releasing yellow pollen all over the house. Is tree pollen in your region causing your allergies?

Spring allergy season might be the most disliked time of year if you are part of the population who suffer from seasonal allergies and the sneezing, watery eyes and endless amount of tissues that likely go along with it. If you’re among that group, you may think all hope is lost and you just have to power through the heavy pollen season. 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 the 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.

What is a 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.1 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.

What are common pollen types?

Pollen is the male fertilizing agent of flowering plants.2 Some plants have large pollen that is carried by bees and other insects.2 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.2

Tree pollen: 

Trees typically produce pollen in spring. Some of the common culprits for spring allergies include birch trees, which can produce pollen as early as January, and oak trees, which have many different species across the globe. Cypress trees are another common allergic trigger, but these will produce pollen up to seven months out of the year.

Grass pollen: 

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.3

Weed pollen: 

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.3 This plant produces large amounts of pollen, particularly in late summer.

a hand holding a bunch of golden rod next to a hand holding a bunch of ragweed.

How is pollen count measured?

Pollen counts are generally taken with an air-sampling device. The device uses sticky rods that test the air regularly. 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.

How can you check the pollen count?

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 getambee.com/pollen-map, which tracks pollen counts in real-time. Simply visit the website, choose your area and check the counts for tree, weed and grass pollen.

When are pollen counts highest?

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.4 It is important to note that many plants pollinate year-round, so checking pollen counts every day throughout the year is recommended.

What is considered a high pollen count?

It depends on which type of pollen you're counting. Remember, these numbers are the number of pollen grains per cubic meter of air:5

  • Tree pollen: 90 or above = high
  • Grass pollen: 20 or above = high
  • Weed pollen: 50 or above = high

So what now?

While there’s nothing you can 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.

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  1. Pollen Counts Defined [Internet]. American Academy of Allergy, Asthma & Immunology; 2024 July 8 [cited 2024 Nov 13]. Available from: https://www.aaaai.org/tools-for-the-public/allergy,-asthma-immunology-glossary/pollen-counts-defined
  2. Pollen Defined [Internet]. American Academy of Allergy, Asthma & Immunology; 2024 July 8 [cited 2024 Nov 13]. Available from: https://www.aaaai.org/tools-for-the-public/allergy,-asthma-immunology-glossary/pollen-defined
  3. Pablos I, et al. Pollen Allergens for Molecular Diagnosis. Curr Allergy Asthma Rep. 2016 Apr;16(4):31.
  4. Fineman F. Hourly Variation of Pollen Counts. [Internet]. American College of Allergy, Asthma & Immunology; 2022 Nov 9 [cited 2024 Nov 13]. Available from: https://acaai.org/news/lowest-pollen-counts-occur-between-400-a-m-and-noon.
  5. Tan S. What to Know About Pollen Count [Internet]. WebMD; 2024 June 13 [cited 2024 Nov 13]. Available from: https://www.webmd.com/allergies/what-to-know-about-pollen-count.