Pollen Count Data

Pollen and Pollen Types
Pollen is essential in the reproduction of flowering plants as it carries the male genetic information to the female part of the flower. Many plants, especially various trees and grasses, use the wind to carry their pollen. Hence, the wind is very important in determining the amount of pollen in the air.

Plants release vast quantities of pollen twice a day, early in the morning and late in the afternoon, but the wind can mix pollen back into the air at almost any time. The count can also depend on wind direction. The majority of flowering plants are insect-pollinated. Consequently, their pollen does not need to be dispersed on the wind and they therefore produce smaller quantities.

During spring-time the main problem for hay fever sufferers is tree pollen. Alder and Hazel can be as early as January followed by Elm, Willow and Ash in March. Pollen from these trees affects only a small percentage of hay fever sufferers but pollen from Silver Birch trees is the most important tree pollen type. This usually occurs in April and affects about 25% of all hay fever sufferers. Birch is followed by the Oak in late April and early May.



Grass Pollen and Hayfever : The most important pollen type for hay fever sufferers in the UK is grass pollen, which causes the highest proportion of allergic reaction



The season starts in late May and continues throughout the summer months to mid August. The main peak is in June and there is a second, smaller peak, in early July. About 95% of hay fever sufferers are allergic to grass pollen. The amount of grass pollen in the air can differ greatly from day to day and even within days depending on the weather.

Weed pollens and fungal spores can also be a common cause of hay fever and are in the atmosphere all year round. However, they have greater significance later in the year.

Pollen Count
The pollen count is a measure of the actual number of pollen grains of a certain type per cubic metre of air sampled, averaged over 24 hours. There are 33 pollen monitoring network sites in the UK, all on exposed rooftops. The reported counts are usually for birch, grass and nettles and refer to the previous 24 hours. The pollen counts show when the various seasons start and end as well as any day to day variation in the amount of pollen in the air.

The pollen count in the Midlands, for example, depends very little on wind direction. Winds from all directions bring pollen and counts are often the highest in the UK. One June the count in Derby was 1024. 150, or more, is considered very high!

If you need to know about the pollen index and pollen forecasts you can view further information on www.nasaleze.com.