What is a seasonal allergy?
An allergy is an exaggerated reaction of the immune system to something in the environment. Seasonal allergies are more common during certain times of the year when irritants or allergens, such as plant pollen, are in greater volume in the environment.
Seasonal allergies also called hay fever or allergic rhinitis, occur when the immune system recognizes something in the environment as harmful, prompting the immune system to produce antibodies called immunoglobulin E (IgE) that remain on the lookout for that substance.
When a person is exposed to the substance again, the antibodies attack the “invader” by releasing immune system chemicals, such as histamine, which causes allergy symptoms. Depending on the seasons, the causes of seasonal allergies vary.
Spring
Tree pollens are a primary source of springtime allergies, and may include these trees:
- Alder
- Birch
- Cedar
- Horse chestnut
- Oak Poplar
- Willow
- Grass pollens are an issue in many states
The springtime allergy season runs from late February into summer.
Summer
During summer months, grass pollens are the dominant allergen, which may include:
- Timothy
- Rye
- Bermuda
- Redtop
- Orchard grasses
- Several weed species
- Bluegrass is a major offender (It has the highest pollen counts of any grass type.)
Fall
The leading source of fall allergies is ragweed. Other autumn allergen-producers include:
- Plants pigweed
- Lamb’s-quarters
- Cocklebur
- Burning bus
- Mugwort
- Sorrel pollens and mold contribute during July to October
Winter
Wintertime allergies tend to originate indoors. Cold-weather allergens include:
- Molds
- Pet dander
- Dust mites
- Cockroach sheddings
While the timing and amount of pollen released can vary, the weather can also affect the level of exposure.
Pollens from trees, grasses, and ragweed spread more easily during dry, warm days and cool nights, whereas mold grows quickly in areas with frequent rain and high humidity.
Unfortunately, there is no way to avoid airborne allergens because they exist in all environments where plants grow.