Guide | July 2023
Understanding the pollen calendar
Your seasonal allergy guide
Pollen allergy symptoms like sniffling and sneezing can be uncomfortable at certain times thoughout the year. A pollen calendar can help you to understand when particular allergens are more likely to be present, and plan accordingly. And the good news is, you may only be sensitive to certain seasonal allergens, so won’t be dealing with them all year long.
Use our pollen calendar below to find out when different tree, grass and weed pollen might affect you, month by month.
Pollen allergy season: when does it start and end?
The pollen calendar begins as early as January, peaks in the spring and summer months, and continues into autumn. While September marks the end of peak pollen counts, you can still experience hay fever in winter as different types of plant pollen are released throughout the year, each with their own symptoms.
It’s helpful to keep a diary of your hay fever symptoms and use our allergy calendar to see which pollens are most likely to be in the air at that time. This may help you understand the types of pollen – and plants – you’re particularly sensitive to.
Types of pollen by season
Spring
From March through to May, tree, grass and weed pollen are all in the air. Tree and grass pollens are common spring allergens as they have peaks at this time of year. Your spring hay fever symptoms may include painful sinuses and a cough.
Summer
Grass and weed pollen peaks in the summer months, so hay fever symptoms can be intense. Some people may experience itchy or watery eyes at this time of year, especially after spending time outdoors or near freshly-cut grass.
Autumn
Pollen season slows down at the beginning of September in the UK. This means hay fever sufferers will start to feel some relief. However, late-release weed pollen can still cause autumn allergy symptoms for some.
Winter
Most pollen allergens are no longer present in the winter, but tree pollen starts its season in January, meaning you could mistake hay fever in winter for a cold.
Types of pollen by month
January
Pollen counts are low this month, but tree pollen is on the rise – specifically yew, alder and hazel tree pollen. This means you can get hay fever in winter and experience symptoms similar to a winter cold.
In January, hay fever may cause:
- sneezing and a blocked nose
- itchy eyes, throat and ears
- difficulty breathing.
February
Five tree pollen variants cause hay fever symptoms in February. These are:
- hazel
- yew
- alder
- willow
- elm.
February also sees the first winter pollen season highs, with hazel and yew pollen counts hitting their peaks until mid-March.
March
Hazel pollen drops off this month, but hay fever rises due to willow, alder, elm and poplar pollen.
Winter tree pollen allergies can start to cause noticeable symptoms, such as:
- watery or itchy eyes
- a reduced sense of smell
- headaches
- disrupted sleep.
April
This month sees the introduction of pine pollen, while birch, ash, oak, and plane pollen all reach their peaks. Weed, grass, oilseed rape, nettle and plantain all begin their season by the end of April.
May
This month tends to have the highest pollen counts. Lime and dock pollen make an entrance and can trigger hay fever, while pine and oilseed rape both peak in May. Plane, oak and birch pollen seasons start to end, but grass pollen starts to reach its high.
June
Allergy symptoms can be high in June. Mugwort pollen season begins, and grass pollen takes off. However, pine, oilseed rape and oak start to decline this month.
July
Mugwort and lime pollen begin to peak in July but grass pollen peaks end. As grass is the most common pollen allergen¹, this will be good news for a lot allergy sufferers.
August
This month, there is less airborne pollen as the summer starts to draw to a close. The dock and plantain pollen season now ends. The following weed pollen allergens may still cause symptoms, however:
- ragweed
- nettle
- mugwort.
September
It’s good news in September, as grass and nettle pollen seasons end, and with this the end of traditional hay fever season too. From this point onwards, you’ll find it easier to enjoy outdoor activities and symptoms should reduce.
October
While peak pollen season has ended, autumn weed allergies can still be triggered. Ragweed pollen is released well into October, so if you find yourself sneezing and itching your eyes at this time of year you may have a sensitivity to weed pollen.
November
Pollen levels are very low this time of year, but some weed allergens and mould spores are still airborne in November, causing late autumn allergies. Mould can be found in bathrooms and other damp areas of the home.
December
Pollen levels are lowest in December and hay fever symptoms should be minimal. That said, winter hay fever can still come from early tree pollen release, specifically from alder, hazel, and yew trees.
If you’re susceptible to pollen allergies, understanding the pollen calendar can be a valuable tool for managing your symptoms. Used in combination with real-time pollen counts, it tells you when particular allergens are at their peak and helps you take proactive measures to minimise exposure.
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Allergens
An allergen is a substance that can cause an allergic reaction by triggering the body’s immune system. Common indoor allergens include dust mite droppings, pet dander, mould, and pollen.
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Bacteria
Microscopic, single-celled organisms that exist in their millions, in every environment. Not all bacteria are harmful, but some can have adverse effects, such as E. coli.
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Benzene
Benzene is colourless, flammable liquid produced by both natural and man-made processes. It’s a natural part of crude oil, gasoline, and cigarette smoke. Indoors, it comes from products such as glues, paints, furniture wax, and detergents.
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Carbon dioxide (CO₂)
A colourless greenhouse gas, which comes from the extraction and burning of fossil fuels. Increased CO₂ levels can impact cognitive function.
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Formaldehyde
This colourless, flammable gas is used in some building materials and household products. Sources can include some fabrics found in flooring and furniture, glues, paints, varnishes, air fresheners, and household cleaners.
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H1N1 virus
This subtype of Influenza A virus, also known as swine flu, caused a global flu outbreak. H1N1 produces respiratory infectious diseases in humans and pigs. Symptoms can be similar to seasonal flu.
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HEPA 13
HEPA (High Efficiency Particulate Air) is an air filter efficiency standard and a measure of a filter’s performance. To achieve this standard, filters must meet a minimum of 99.97 per cent particle removal at the most penetrating particle size.
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Humidification
A process of increasing air moisture content through the addition of water vapour or steam. Humidifiers can add moisture to the air in dry conditions, creating a more comfortable indoor environment when needed.
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Microns
Airborne particles are usually described in microns. One micron is equal to one-millionth of a metre. The human eye can see debris and dust that are approximately 25 microns in size.
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Nitrogen dioxide (NO₂)
Nitrogen dioxide is a liquid below 21.2 °C and a gas at higher temperatures. It is toxic to humans in both states. Gas stoves and space heaters are the most common indoor sources of NO₂ emissions. Other sources include improperly vented furnaces and water heaters.
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Pet dander
Pet dander is made up of tiny particles of skin, saliva and urine, shed by animals with fur or feathers. Pet dander lingers in the air before settling on surfaces such as furniture, bedding, and fabrics. Exposure to these airborne particles can trigger allergies.
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Particulate matter (PM)
Particulate matter contains microscopic solids or liquid droplets, measured in microns. Indoor PM can be generated through many day-to-day activities such as cooking, cleaning, and the burning of candles and fires.
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Purification
The process of making something free of any contaminants or physical impurities. Air purification is designed to filter the air in your home – removing pollutants such as dust, allergens and viruses.
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Volatile organic compounds (VOCs)
Volatile organic compounds are potentially harmful gases found in many household products. Common sources include paints, varnishes, air fresheners, cosmetics, and cleaning products.
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Pollen
Pollen is a powdery substance released from seed plants as part of their reproduction process. It typically appears from trees in the spring, grasses in the summer, and weeds in the autumn. Pollen grains are among the most common allergens.
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House dust mites
Dust mites are tiny insects that commonly live in household dust. They are one of the biggest causes of allergies. Each gram of house dust contains approximately 1000 dust mites.
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Aspergillus mould
A common name for a visible group of fungi, mould thrives wherever there is dampness – sending out millions of spores into the air. Exposure to mould occurs via inhalation, skin contact, or ingestion.
Read more
Sources:
¹Allergy UK (2023). Pollens and mould in the garden. Available at: https://www.allergyuk.org/resources/pollens-and-moulds-in-the-garden-factsheet/
²University of Worcester (2023) Regional Pollen Calendars. Available at: https://www.worcester.ac.uk/about/academic-schools/school-of-science-and-the-environment/science-and-the-environment-research/national-pollen-and-aerobiology-research-unit/pollen-calendar.aspx
