IOA :: Pollen

Pollen

Pollen is the male seed of plants and trees. It is made up of tiny grains with a wide variety of shapes, depending on the plant species. Some pollen grains have prickles, others holes or slits. The average size is about 0.05 mm across, which means that they are invisible to the naked eye. Pollen grains contain a large number of allergenic proteins.

Plants differ in the way they disperse the pollen in the air.

Anemophilous pollens have small, pale coloured flowers and are dispersed by the wind. These pollens are produced and released in high quantities, and because they are dry and very light they can be carried by the wind over very long distances. This is why some people suffer from allergic reactions to the pollen of plants that do not grow in their immediate neighbourhood. This type of pollen is the most allergenic, simply because it is produced in high quantities and can stay suspended in the air for a long time, increasing the chances of a person being exposed to it. The main culprits for pollen allergy are anemophilous plants that fall into three families: graminaceae (grasses), trees and herbaceous plants (weeds).

Entomophilous pollens are dispersed by insects and birds that feed on flowers of the plants that produce them. To attract insects, entomophilous plants have brightly coloured, sweet-smelling flowers. They produce small quantities of heavy sticky pollens that will not float in the air. Due to this characteristic, the chances of coming into frequent contact with this kind of pollen is very low. Therefore, entomophilous pollens are rarely involved in allergy.

Peak pollen periods occur at different times in different parts of the world. Below you can find a calendar showing the pollen seasons of most of Europe’s allergenic plants. The seasons indicated cover the pollination period all over Europe. You should be able to get a similar calendar for your country which would give you more accurate information about the pollen seasons of the place where you live. This is the best way to plan your defence against allergic attacks.

The concentration of pollen in the air is not constant throughout the pollen season, weather conditions can influence it very much. Pollen release is maximal in hot, dry weather and wind helps to disperse it. So, under these weather conditions, there is a high risk of being exposed to large amounts of pollen. Rain, on the other hand; washes pollen out of the air, reducing the risk of allergy.

Pollen allergy sufferers experience an allergic attack when the concentration of pollen in the air reaches or surpasses a certain threshold. This usually is within the range of 20-30 grains/m³ but varies according to the species in question. At the beginning of the pollen season the threshold concentration that triggers allergy symptoms is higher compared to the peak or end of the season (i.e. threshold concentration for birch pollen is around 80 grains/m3 at the beginning of the season and 30 grains/m3 towards the end of the season) because exposure increases sensitivity.

Avoiding the triggering allergen is the oldest treatment strategy in allergy. In most cases, this will not cure your disease but it can limit the harm. With pollen (as well as with most allergens) complete avoidance is virtually impossible, but still we can reduce our contact with them.

Symptoms: Allergy to pollen is expressed mainly as allergic rhinitis, allergic conjunctivitis and more rarely as asthma. Symptoms are usually confined to the pollen season.

Don’t give away your beautiful flowers

With rare exceptions, people allergic to pollens can keep and grow ornamental flowers without danger. “Beautiful flowers” produce entomophilous (insect-carried) pollens which usually are not allergenic.

Beware of honey!

It might contain pollen which could set off an allergic attack.

Cut down your attacks! Check the pollen calendar.

You should check the pollen calendar for your part of the world and, as much as possible, avoid being outdoors during the pollen season of plants to which you are allergic.
Remember:

the peak pollen season may be delayed by a month or more but is also shorter in mountainous regions.
in different regions of the world, the pollen season of a given plant may be different. Therefore if you travel, don’t forget to check the pollination seasons in the countries that you are visiting. If your trip coincides with the peak pollen season, you should try to delay your trip. If you must go, remember to take your drugs with you.

Mowing short grass that is blooming is usually not harmful. However, cutting long grasses (such as those you can find on the meadows in summer) is one of the most harmful practices for anyone allergic to grass pollen.
It used to be believed that tree pollens, being relatively heavy would not travel very far. However, photos from space showing the tree pollen cloud from Denmark crossing the North Sea have clearly shown that this is not the case.

Keys, hand bag, mobile phone, money and….ah yes, the pollen forecast

During the pollen season, always check the pollen forecast if you go for a walk, if you schedule a trip outdoors or a holiday. The Internet is probably the best source, but you can also find information in newspapers, on television or radio.

Beware of Hay fever

From The Times
May 27, 2006

Pollen surge that could get right up your nose
By Lewis Smith, Environment Reporter

Hay fever sufferers were advised yesterday to prepare for the highest pollen count in living memory.
A combination of wet and warm weather in the past few weeks has provided ideal conditions for the grasses that make early summer a misery for the 12 million people in Britain who suffer from hay fever.

Pollination has been slightly delayed by the recent rain but the country’s 150 species of grass are expected to create high pollen counts next month.

Pollen counts of 50 grains per cubic meter are considered high, but, last year, levels of more than 900 grains were recorded. Next month’s count could exceed 1,000 grains.

The number of allergy sufferers has been rising steadily over the past century. Recent studies have suggested that people living in urban areas suffer more than those in rural areas because pollen combines with pollutants to become even more allergenic. Research has indicated that climate change is having an effect on the severity of attacks. Long periods of hot and dry weather cause plants to produce more protein which makes the pollen more allergenic.

Tip: Some basic precautions

Avoid picnics or camping holidays during the high pollen season
Take your holidays at the seaside, where there is less pollen
During the pollen season, keep your car windows shut
Keep your windows closed in the early morning if you live in a green area or the country side and in the evening if you live in an urban area
Sleep with your bedroom windows shut
Stay indoors as much as possible during hot, dry, windy days
Take your treatment before the season starts and use it regularly throughout, even on days when you have no symptoms - it works better that way