Certain spore types reach peak levels in dry, breezy weather. Some need high humidity, fog or dew to release spores. This group is abundant at night and during rainy periods. Pollen allergies cause sneezing, runny or stuffy nose, coughing, postnasal drip, itchy nose and throat, dark circles under the eyes, and swollen, watery and itchy eyes. For people with severe allergies, asthma attacks can occur.
Mold spores can contact the lining of the nose and cause hay fever symptoms.
They also can reach the lungs, to cause asthma or another serious illness called allergic bronchopulmonary aspergillosis. To collect a sample of particulates in the air, a plastic rod or similar device is covered with a greasy substance. At the end of that time, a trained analyst studies the surface under a microscope. Pollen and mold that have collected on the surface are identified by size and shape as well as other characteristics. A formula is then used to calculate that day's particle count.