OUTDOOR ALLERGENS

Molds are microscopic fungi that live in almost every environment, indoor and outdoor. Molds reproduce by releasing tiny spores that float in the air. Spores from two types of molds, Alternaria and Cladosporium, can cause or worsen asthma symptoms in asthmatics allergic to mold. These molds can be found both indoors and out. Outdoor mold is found in the soil and vegetation using dead plant matter as food. Molds thrive in dark, damp areas. Some molds release spores on warm, dry summer days, and others prefer rainy fall nights. Outside, molds begin releasing spores in early spring and continue until late fall.

Pollens are a powdery substance produced by flowering plants that contains male reproductive cells. Small pollen grains, from trees, grasses and weeds, are light and remain airborne for long periods of time carried by wind to fertilize other plants. Larger pollen grains, from plants with bright flowers like roses, are heavy and rely on insects to carry them to other plants for fertilization. Usually, these large waxy pollens do not trigger allergies. Generally, small pollen allergens come from trees in early spring, grass in late spring and summer, and weeds in summer and fall.