Why do pollen and mold counts vary so much from day to day?
Changes in temperature, wind conditions, humidity, or precipitation can affect the counts greatly. • Temperature: A sudden temperature drop lowers the pollen count significantly. Certain pollens are seasonal. Trees are dominant in the spring, grasses occur in late spring and early summer, and weeds grow from late summer until the first hard frost. • Wind: Pollens are small, light, and dry so they are easily spread by wind. The distance the pollen travel can depend on whether the wind is strong or calm that day. • Humidity: When the air is humid, pollen becomes damp and heavy with moisture keeping it still and on the ground. • Precipitation: Rains tend to “cleanse” the air of pollen. When the pollen is wet, it becomes heavy with moisture keeping it on the ground.
