|
About the pollen index
The pollen index is supplied by the National Pollen and Aerobiology Research Unit. The pollen forecasts are made using information from the National Pollen Network, local vegetation, weather patterns in the winter and spring that influence grass growth, and the weather forecasts. The pollen forecasts can help hay fever sufferers to plan their activities and medication.
It is important to note that this is an index of the risk of being affected by airborne allergenic pollen and is not the actual pollen count.
During the spring months the main problem for hay fever sufferers is tree pollen. Some types such as alder and hazel can be in the air as early as January. These types are followed by elm, willow and ash in March. Pollen from these trees affect only a small percentage of hay fever sufferers but can cause symptoms in some allergic people. The pollen from silver birch trees is the most important tree pollen type for hay fever sufferers and usually occurs in April. This pollen type affects about 25% of hay fever sufferers. The season usually lasts for about four weeks and counts will be high on dry, warm days with some wind in areas where there are birch trees. The birch tree pollen season is followed by the oak tree pollen in late April and early May, although oak affects fewer sufferers than birch.
The most important pollen type for hay fever sufferers in the UK is grass pollen. This season starts in late May and continues through to mid August, with the main peak occurring usually in June and a second smaller peak typically occurring in early July. About 95% of hay fever sufferers are allergic to grass pollen. The amount of grass pollen in the air can differ a lot from day to day and even within days depending on the weather.
Weed pollens affect a small percentage of sufferers from June to September with a peak in August. The pollen index changes emphasis slightly during the season to reflect the predominant types of pollen:
- Tree pollen forecasts from March until May
- Grass pollen forecasts from May until August
- Weed pollen forecasts from the beginning of August until the end of August
- Fungal spore forecasts from the end of August until the end of November.
|
