Pollen is a fine powder produced by certain plants. During the spring, summer,
and fall seasons, it is released into the air and picked up by the wind. The wind
carries it to other plants so they can make seeds. But while it's traveling in the
wind, pollen gets into the air we breathe. Many people are allergic to it, including
people who have asthma.
When they breathe in pollen, it can trigger their asthma symptoms.