Apr 12, 2024 - News

How climate change impacts Seattle's allergy season

Illustration of tiny toy people climbing up a mountain of pollen with a large flower growing from the middle

Illustration: Natalie Peeples/Axios

While sunshine can bring smiles for some, it can bring suffering for others. Spring is not only the start of warmer weather but the beginning of allergy season, which has only become longer in recent years.

Why it matters: Climate change and warmer springs are causing plants to produce higher concentrations of pollen for longer periods of time.

What they're saying: "We're seeing allergy seasons become more intense and lasting longer," said Dilawar Khokhar, a clinical assistant professor at the Division of Allergy and Infectious Diseases at the University of Washington.

  • "We used to think of ragweed as kind of ending in August, but now ragweed season can extend into September."

Flashback: Last year, Everett was the pollen capital of the West Coast. The city's pollen count increased by 54% from 3,489 parts per million in 2022 to 5,386 ppm in 2023, per a study by online allergy clinic Wyndly.

  • Seattle recorded its highest pollen count — 1,998 ppm — last May.

Zoom in: There are three types of pollen: tree, grass and weed.

  • Tree pollen begins to infiltrate the air starting in late February through the end of April — the start of the annual reproductive cycle for evergreens — and grass pollen season begins shortly after.

Threat level: The Puget Sound region's comparatively high density of trees — including cedar, juniper, alder, elm, maple, birch and cottonwood — creates a perfect storm for allergy sufferers at the onset of warmer weather.

  • Washington produces much of the country's supply of Kentucky bluegrass turf seed, meaning grass pollen is likely heavily present in the air during peak growing season.
  • Grass pollen levels peak in May and June, when people most often feel allergies — symptoms like sneezing, itchy nose, watery eyes and nasal congestion.
  • Increased pollen levels can also exacerbate asthma symptoms, causing wheezing, coughing and difficulty breathing for some.

The intrigue: Allergy season in Seattle increased by 17 days on average between 1970 and 2021, per an analysis from Climate Central, a nonprofit climate news organization.

  • That's based on the number of days between the last freeze each spring and the first freeze each fall.

What they found: Allergic rhinitis, the technical term for hay fever, "is arguably the most expensive medical condition in the U.S., because of the vast number of people that are affected," Shyam Joshi, an allergist at Oregon Health & Science University, told Axios.

  • It's likely that with more exposure to allergens and pollution, more people are developing allergies over time, he added.

The bottom line: Reduce the amount of allergens on your person by changing your clothes and washing your hands and face after being outside.

  • Close your windows at night and while you're driving.
  • Consider investing in a HEPA air filter for your bedroom.
  • If that is not enough, Joshi recommends steroid nose sprays like Flonase over antihistamine tablets.
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