Behind the Forecast: Why Fall allergies are so bad

Science Behind the Forecast: Fall Allergies (9/13)

LOUISVILLE, Ky. (WAVE) - Allergies are not just a Spring problem; there are a plethora of triggers in the autumn as well.

It's expected to be a bad late summer, early fall for people who suffer from ragweed allergies because of our wet spring.
It's expected to be a bad late summer, early fall for people who suffer from ragweed allergies because of our wet spring. (Source: Wikipedia)

In the fall, ragweed is the main culprit. Ragweed pollen counts are highest in mid-September. Ragweed grows throughout the U.S. (it mainly thrives in the Midwest and on the East Coast) and releases pollen from August through November. Ragweed only lives for a season, but a single ragweed plant produces around one billion pollen grains that each travel for hundreds of miles. “The most common fall allergy is ragweed, which pollinates from August 15 to early October through most of the United States and parts of Europe,” Dr. Jay M. Portnoy, Chief of Allergy, Asthma, and Immunology at Children’s Mercy Hospitals & Clinics in Kansas City, Mich, told Live Science. “It causes hayfever, with symptoms that include sneezing, runny nose, stuffy nose, itchy nose, and itchy, watery eyes.”

Other plants that trigger fall allergies, according to the American College of Allergy, Asthma, and Immunology (ACAAI), include:

  • Burning bush
  • Cocklebur
  • Lamb’s-quarters
  • Pigweed
  • Sagebrush and mugwort
  • Tumbleweed and Russian thistle

Mold is also a trigger in the fall. Rotting fall leaves create an environment for mold to thrive then release spores into the air to reproduce.

Indoors, dust mites reign supreme. They thrive and multiply in warm, humid locations like heating ducts. Turning on the heater to avoid colder temperatures outdoors may stir up the dust mites lingering in your home.

The following weather factors can influence the severity of symptoms:

  • Tree, grass and ragweed pollens flourish during warm days and cool nights
  • Molds grow quickly in the heat and high humidity
  • Pollen levels usually peak in the morning
  • While rain washes pollen away, pollen counts can soar after rainfall as the trees blossom
  • Calm winds keep airborne allergens are grounded
  • Windy and warm days help pollen counts soar

The lower humidity in a home during the fall and winter months can be another trigger for allergy symptoms. The lower humidity dehydrates out the nose lining causing it to become swell; this leads to a stuffy and runny nose.

Certain types of weather can trigger asthma symptoms. The Asthma and Allergy Foundation of America (AAFA) says high heat, cold temperatures, sudden weather changes, rain, thunderstorms, and high humidity can all be triggers. Heat and humidity help dust mites and mold thrive. Ozone and pollen counts rise during stretches of dry weather adding to the aggravation.

Dry and cold air can cause airways to narrow, according to the AAFA. Heavy rain from thunderstorms can break apart pollen grains, making them easier to inhale. Strong winds in a storm throw the particles into the atmosphere; eventually, we breathe them in.

In 2018, the AAFA said Louisville was the second most challenging place in the United States to live with fall allergies. In 2019, Louisville was number seven on the list of the Top 10 Asthma Capitals.

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