What does a pollen count mean?

A pollen count gives you the average number of pollen grains per cubic meter of air. See our pollen counting page for details on the calculations used to determine that number. Generally, when there are low amounts of pollen in the air, only those extremely sensitive to pollen or molds will experience allergic symptoms. A moderate amount of pollen will  cause many people who are sensitive to pollen or molds to experience symptoms. High amounts will cause most sensitive individuals to experience symptoms and very high amounts will cause virtually all sensitive individuals to experience symptoms.

Graph and Scale Explanation

The purpose of the pollen graph is to quickly inform the reader of the day's pollen/spore conditions.  The pollen graph also provides the reader with a reference point so the count can be interpreted.   In each daily count the average grains/spores per meter³ of each category of pollen/spores (trees, grasses, weeds and molds) will be calculated.  The calculated numbers will be compared against the chart below and graphed accordingly. 

The chart was adapted from an article in The Pollen Monitor by David A. Frenz.  Frenz's chart was derived from pollen and mold counts in 51 cities in the United States by Burge (1992).  Frenz arranged the count data for each pollen/spore class in descending order and divided the data into four classes (low, medium, high and very high) according to the percentile.

References

Burge, HA.  (1992).  Monitoring for airborne allergens.  Ann Allergy 69:9-18.

Frenz, David A. (May 1995) Making Sense of the Numbers: What to do with a pollen count once you have one.  The Pollen Monitor: Newsletter of Multidata, Inc.  Vol. 1 No.11 Page 3.