The pollen count tells you how much pollen is in the air. It measures the number of grains of pollen (on average) in a cubic metre of air.
In general, the higher the pollen count the more someone will feel the effect of hayfever and suffer symptoms.
The pollen count varies from place to place and is influenced by various climatic and environmental factors (such as sunshine levels, wind, plant types, altitude).
A hayfever sufferer can be affected by one or more types of pollen. For the UK, the three major types are:
Mould and fungal spores can also cause hayfever. These have most impact mid-May to mid-October, but can affect some sufferers all through the year.