The concentration of tree pollen
increased and fluctuated between 6000 and 19 800 grains [cm.sup.-3], that of shrubs between 150 and 1000 grains [cm.sup.-3], and herbs between 2900 and 7100 grains [cm.sup.-3].
Part of Jensen's job is to count grass, weed and tree pollens
An estimated 25-35 million people suffer from allergy caused by Japanese cedar tree pollen
or house dust mites.
Some people are allergic to tree pollen
released during the spring, some are affected by grass pollen, released during the end of spring and beginning of summer, and weed pollen, released any time from early spring to late autumn.
Grahame said: "People suffering at the moment most likely will be allergic to tree pollen
, from birch and ash trees.
for example, usually reaches its highest levels in the spring months whereas grasses pollinate between May and August - so it's most likely that this is the type of pollen that is affecting you.
The study also found that 14% were specifically allergic to tree pollen
. Tree pollen
is particularly high in London in April as this is when pollen from High Birch and London Plane trees is released and tree-pollen counts had been high on the day of the 2010 marathon itself.
For example, USDA will place bee hives around the injection areas to see whether the pesticide affects entire bee colonies, rather than just sickening individual bees that encounter chemical-laden tree pollen
Hay fever is triggered by airborne irritants - usually grass and tree pollen
Birch tree pollen
is currently at its peak in the Midlands and will be followed shortly by the grass pollen season, which is responsible for hay-fever in 95 per cent of sufferers.
She cited the example of the birch tree pollen
season, which affects around one in four hay fever sufferers.
Bizarrely, Grace has no reaction to either the fruit or tree pollen
on their own.