Everything You Need to Know About The Pollen Count

Content by

Chemist Click

Authored by

Abbas Kanani MRPharmS

Last Updated

07 July 2025

Table of Contents

What is Pollen?
How is Pollen Count Measured?
What is a High Pollen Count?
How the Weather Affects Pollen Levels

If you suffer from seasonal allergies, the phrase "pollen count" probably isn't new to you, but understanding what it means can make a big difference in managing your symptoms.

The pollen count measures how much pollen is in the air on a given day, and it can help you plan your outdoor activities, when to take medication, and even how you dress.

In this guide, we’ll break down how it works, why it matters, and how to use it to stay one step ahead of allergy season.

What is Pollen?

Pollen is a fine powder produced and released by plants. They do this as part of their breeding process to fertilise other plants of the same species.

Pollen is well known for causing allergy symptoms for people with hay fever, such as sneezing and itchy eyes, but not all types are allergenic.

Pollen from specific plants, like trees, grasses, and weeds, is more likely to cause symptoms.

How is Pollen Count Measured?

Pollen is measured using an air sampling device, either Burkard traps or Rotorods. Airborne grains are caught onto a sticky surface and collected over a 24-hour period. The number and types of different pollen are then analysed under a microscope. Meteorological organisations such as the Met Office monitor pollen levels.

What is a High Pollen Count?

A high count usually exceeds 50, which is when pollen symptoms are apparent in most people with hay fever.

The reading depends on the type of pollen, but once measured, the number of particles is represented per cubic metre.

Here are the estimated levels for a ‘high’ pollen count depending on the different types of pollen:

Tree pollen: 90–1,499 grains/m³
Grass pollen: 20–199 grains/m³
Weed pollen: 50–499 grains/m³

A question we’re regularly asked at the pharmacy is, "Is the pollen count high today?".

A high pollen count is usually measured in advance, which can be helpful for people with hay fever to plan and prepare for symptoms by using a hay fever treatment or allergy nasal spray ahead of time.

You can gauge whether you’re likely to experience tree pollen allergy symptoms or grass pollen allergy symptoms, as the forecast shows you the type of pollen and severity for each day.

How the Weather Affects Pollen Levels

Does Rain Make Pollen Worse?

Yes, when raindrops fall onto pollen particles, they can break, increasing the concentration in the air.

Different Times of the Day

The pollen count is usually the highest in the morning. Just after sunrise, most plants release pollen as the humidity drops and the air gets warmer.

The count typically stays high until early afternoon because of a combination of rising temperatures and breeze, which keeps the pollen circulating in the air.

It begins to drop late afternoon as the air begins to cool down, and as we move into night, the wind typically slows down.

Time of Day	Pollen Count Trend	Why?
Early Morning	Highest	Start of pollen release
Mid-Day	Still High	Warmth and wind circulate the pollen
Late Afternoon	Moderate	Cooling air starts settling
Night	Lowest	Cool, damp air stabilises pollen

What Effect Does Temperature Have on Pollen?

Warm weather triggers plants to produce more pollen. It creates the perfect environment to accelerate growth and flowering which leads to an extended and strong hay fever season, and in some cases an early pollen release.

On the other hand, colder temperatures can slow or delay the production of pollen, as well as reduce the amount that is airborne by keeping it settled.

Is Pollen Carried by the Wind?

Yes, pollen is carried by the wind. Some pollen relies on the wind to pollinate another flower, known as anemophily. Pollen counts are typically higher on windy days.

Does the Sun Affect Hay Fever?

Yes, it indirectly affects hay fever. Sun rays raise the temperature, and higher air temperatures lead to a boost in pollen production.

When more pollen is released into the air, it increases the risk of exposure, meaning that people with hay fever are more likely to experience symptoms.

Sources

Metoffice.gov.uk (n.d). Pollen Forecast. Retrieved 16th March 2025, from: https://weather.metoffice.gov.uk/warnings-and-advice/seasonal-advice/pollen-forecast#?date=2025-04-16

Whilst all of our content is written and reviewed by healthcare professionals, it is not intended to be substituted for or used as medical advice. If you have any questions or concerns about your health, please speak to your doctor.