Pollen count is the measurement of the number of grains of pollen in a cubic meter of air. The higher the number, the more people will suffer if they are allergic to a particular pollen (hay fever). Usually, the counts are announced for specific plants such as grass, ash, or olive. These are tailored to what is usually a common plant in the area being measured.
One method of taking the sample uses a silicone grease-covered rod that is rotated in the air to collect the pollen. The rod is rotated periodically during the collection period to gather samples through an entire 24-hour day. The rod is then removed and taken to a lab where the collected material is analyzed for the type of pollen and its concentration.
In the UK, the public announcement of the pollen count was popularised by Dr. William Frankland, an immunologist.
According to a study by Leonard Bielory, M.D. that was presented to the American College of Allergy, Asthma & Immunology, climate changes are expected to cause pollen counts to more than double by 2040.