Pollen allergy – peak seasons in the UK
Seasonal allergic rhinitis, commonly known as hayfever, is caused by exposure to grass pollen, tree pollen and other plant pollen which is released into the air.
In the UK pollen exposure is most common in the spring and summer months, but different species of plant pollinate at different times of year, so some individuals may experience symptoms at specific times and none at others.
Sufferers of allergic rhinitis are advised to limit their exposure to airborne pollen as far as possible during the months in which they are affected. Some strategies which may help include:
- Reviewing local weather reports including pollen counts and limiting time spent outside when the count is high.
- Avoiding drying laundry outdoors, particularly clothes and bedding, when pollen counts are high.
- Keeping doors and windows closed during peak months for pollen exposure.
- Avoiding gardening, lawn mowing and other outdoor work during peak months for pollen exposure.
The exact timing, peak, and severity of pollen release will vary from year to year according to the specific weather conditions, with wind, temperature and rainfall all having some effect.
The expected period of release and peak for the most commonly encountered UK pollen types is as follows:
Alder pollen (Alnus)
January to April, peaking in March
Alder is a deciduous tree closely related to hazel, hornbeam, oak, and chestnut. It grows in relatively close proximity to water, often found bordering streams, rivers and springs. Alder is a wind-pollinated tree which flowers in March or April, producing clouds of yellow pollen during the peak months.
Hazel pollen (Corylus)
January to April, peaking February to March
Hazel is a deciduous tree native to woods and hedgerows, and particularly the slopes of hills. It is closely related to birch, alder and beech. Hazel is wind pollinated, and flowers early in the year, with peak pollination between February and March.
Yew pollen (Taxus)
January to April, peaking in March
Yew is a conifer growing to between 10 and 20 metres tall, and recognisable by its bright red berries. The needles, bark and seeds are highly toxic to humans and can be fatal if ingested or the volatile oils absorbed. Yews bloom and release abundant amounts of pollen in the spring, peaking in March.
Elm pollen (Ulmus)
February to April, peaking in March
Elm is a tall deciduous tree growing to as much as 40m with a distinctive vase shaped crown. It is found in woods and hedges as well as by roads and streams. Elm is wind pollinated, usually flowering early in the spring and peak pollination occurs in March.
Willow pollen (Salix)
February to April, peaking in March
Willows are small (3 to 15m) shrubs or trees commonly found in wet environments such as riverbanks and lake shores. They are closely related to aspens, cottonwoods and poplars. They are among the earliest flowering trees in the UK, with peak polination occuring in March.
Poplar pollen (Populus)
March to May, peaking in March
Poplar is a medium-sized deciduous tree, growing to heights of up to 16 to 27m. It is common in towns and cities where it is often used along boulevards or around squares. In the UK, poplar flowers in spring, with peak pollen production during March.
Birch pollen (Betula)
March to June, peaking April to May
The common silver birch is a single-stemmed, deciduous tree up to about 25 metres tall, with distinctive silvery bark. Birch pollen is highly allergenic and is a significant cause of asthma and rhinoconjunctivitis. Pollination occurs from spring to early summer, peaking between April and May.
Ash pollen (Fraxinus)
March to May, peaking in April
The European ash is a broad, deciduous tree, growing up to 35 m in height. Ash trees are wind pollinated, with pollen travelling up to 110 metres from the tree. They spread large amounts of pollen during the flowering season, which in the UK is from March to May, with the peak occurring in April.
Plane pollen (Plantanus)
March to May, peaking in May
The London plane tree is easily identified by its distinctive bark which peels in large flakes. It is commonly found in urban areas of the UK, planted along streets and in squares. Over half of the trees found in central London are of this species. London plane is wind pollinated and pollination peaks during May.
Oak pollen (Quercus)
March to June, peaking in May
Oaks are large deciduous trees with broadly spreading canopies, found throughout the UK both in rural areas and in urban or suburban parkland. Flowering generally occurs in spring but may vary based on local temperatures and weather conditions, with pollination peaking around May.
Oil seed rape pollen (B. napus)
March to July, peaking May to June
Oilseed rape is a common food crop in the UK, grown principally for oil production. Oilseed rape fields are easily recognisable by the bright yellow flowers which are characteristic of this species. It is partially wind pollinated, with peak pollen release occurring from May to June.
Pine pollen (Pinus)
April to July, peaking in May
Pine is a coniferous tree growing up to 35m in height, with upward pointing branches and a narrow, tapering shape. The majority of species flower in spring and early summer in the UK, peaking around May. While the pollen count is high, the individual pollen grains are relatively large, which can reduce sensitisation.
Grass pollen (Gramineae)
May to September, peaking June to July
Grass pollen is one of the most common causes of allergic rhinitis (hayfever), and may also cause contact dermatitis in sensitised individuals. In the UK the grass pollen season runs from spring through to early autumn, with its peak in summer. Activities such as mowing and baling of hay may increase levels of pollen locally.
Lime pollen (Tilia)
June to July, peaking in June
Lime trees are a common ornamental tree in the UK, growing to as much as 30m tall. They may be found in parks and ornamental gardens or lining streets or avenues. Limes flower in summer, with peak pollination usually occurring in June.
Nettle pollen (Urtica)
May to September, peaking in June
Nettles are a well-known weed which are renowned for their painful sting. They can be found growing wild in wastelands, woodland, meadows and on railway embankments. Nettle pollen is not highly allergenic but may cause symptoms in sensitised individuals. The peak season for nettle pollen in in June.
Dock pollen (Rumex)
May to August, peaking in June
Dock is mainly found in meadows and pasture land, as well as in some coastal areas. It is a small herb with reddish flowers which blossom as early as May or as late as September, depending on the prevailing conditions. In the UK, peak pollination is generally during June.
Mugwort pollen (Artemisia)
June to September, peaking July to August
Mugwort is a species of plant usually categorised as a weed, which can be found in wasteland, embankments and meadows. It bears small yellow or red-brown flowers which blossom from early summer to early autumn. Mugwort pollen release peaks between July and August in the UK.
