Common Allergens: Environmental Allergies
In theory, just about anything could trigger an allergic reaction, but some substances seem to affect people more than others. Most common allergies are caused by seasonal allergens, such as airborne pollens and mold spores.
Here’s a little more information about the causes of environmental allergies:
Pollen
Tree, grass, and weed pollens -- carried in the air by wind -- are the main culprits in most common allergies. In North America, peak pollen season is typically between February and October, but in some regions it may start earlier, end later, or continue year-round.p>
Early Spring: Trees kick off the pollen season in early spring with oak, elm, birch, ash, poplar, sycamore, maple, cypress, and walnut causing the most problems.
Late Spring/Early Summer: Grasses release their pollen in late spring and early summer. Common allergy-inducing grasses include timothy, bermuda, orchard, sweet vernal, and Kentucky blue grass.
Late Summer/Fall: Late Summer/Fall: Weed pollen closes out the pollen season in late summer and fall. Ragweed is thought to be responsible for the majority of common allergies in late summer and fall, but other weeds, such as sagebrush, tumbleweed, and pigweed, may cause allergic reactions as well.
Winter: Some people may experience allergy symptoms outside of the active pollen season. This may be caused by pollen allergens that are still present in soil or plant debris; by winter-pollinating trees, such as juniper; or by another type of allergen, such as pet dander, dust mites, or mold.
Mold
Some outdoor molds can cause seasonal allergies during spring, summer, and fall.
Outdoor molds grow mostly on soil or decaying plant material, such as leaves, rotting wood, or compost piles, but may also be found on healthy plants. Digging, raking, or otherwise disturbing these mold habitats causes tiny mold spores to be released into the air. Changing weather conditions -- wet, dry, or windy -- can also trigger the release of mold spores.
If your allergies last all year round or flare up during colder months, when you spend more time indoors, you may be allergic to dust, animal dander, or indoor molds. Find out how to reduce common allergens in your home.
