Fall weather and late-season allergies
Fall officially began earlier this week, and as temperatures cool across the region, many are now facing the return of a seasonal challenge: fall allergies.
While spring is often associated with blooming flowers and high pollen counts, for some, allergy symptoms are at their worst in late summer and early fall. Sneezing, itchy eyes, congestion and runny noses are common complaints this time of year, and in many cases, they're caused by a specific set of seasonal allergens.
The phenomenon of fall allergies dates back hundreds of years. The term “hay fever” originated in the early 1800s when farmers experienced allergy symptoms during harvest season. Though not caused by hay, the name stuck and is now widely used to describe allergic rhinitis related to airborne pollen and mold.
In Missouri, common fall allergens include ragweed, mold spores, tree pollen and grass pollen. While tree and grass pollen are more prevalent in the spring and early summer, ragweed and mold take over in late summer and fall.
Weather patterns during the autumn months play a critical role in determining the severity of allergy season. Dry, windy conditions are especially problematic, as they allow loose pollen and mold spores to become airborne and travel long distances. Ragweed, which blooms during this period, is particularly troublesome because its lightweight pollen can spread for miles.
Warm temperatures tend to foster the growth and lifespan of Ragweed, which doesn’t stop producing pollen completely until the first frost of the fall season. While ragweed pollen levels tend to decrease as temperatures cool, it takes a hard freeze to end its life cycle and eliminate the airborne allergen completely. This rule also holds true for other late-season pollen producers.
Rainfall also impacts pollen levels in multiple ways. While rain can encourage pollen production, wet weather can temporarily suppress pollen in the air by weighing it down, offering short-term relief for those with allergies. Aside from its effects on airborne pollen levels, cleansing fall rain can also help clear the air of other allergens, such as dust, which often fills the air around harvest time.
For those affected by fall allergies, taking preventive measures—such as staying indoors on dry, windy days, keeping windows closed, and using air filters—can help reduce exposure and ease symptoms as the season progresses.
