They are not very accurate. Years ago I was in a pollen counting course at the University of San Francisco. They had pollen counters on the four corners of the hospital about 20 stories up. It was two blocks long and one block wide. Those four pollen counter reports always look liked they came from four different parts of the world, so it's not terribly accurate as far as real numbers go. What is important is that it tells you what's in season, but everybody knows what season. The mold count is high when it's going to rain or right after rain. It's ragweed season in August and September. Everybody knows when it's cedar season, because the trees start blowing up and yellow powder fills the air. A pollen count is just something that helps you determine it's an allergy rather than a cold. If you see that the ragweed count is high and all of your neighbors have red eyes as well, its probably an allergy.
