Part of a plant’s reproductive system, pollen consists of microscopic particles that must be transferred to various areas of a plant’s reproductive parts to produce viable seeds. Bees and other insects cross-pollinate plants, as well as wind. Pollen counts are based on how much pollen is in a cubic meter of air measured over 24 hours. 

What does pollen do to your body? Pollen is responsible for many seasonal allergy symptoms, as well as asthma. Common sources of pollen-producing asthma come from plants such as ragweed, lamb's quarters, Russian thistle, Kentucky bluegrass, Bermuda grass, Johnson and Timothy grasses, and various wind-pollinated trees like ash, elm, oak, hickory, box elder, pecan, and mountain cedar.