Apr 11, 2024 - Climate

How climate change impacts Portland'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 not only marks the start of warmer weather, but of allergy season too, 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.

What they're saying: "Every year I see more and more severe allergies that patients come in with, significantly affecting quality of life and their ability to function," Shyam Joshi, an allergist at Oregon Health & Science University, told Axios.

Flashback: Last June, grass pollen counts in Eugene reached 1,300 particles per cubic meter of air — the highest level in over 25 years — and warm winds carried those allergens throughout the Willamette Valley.

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

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

Threat level: Oregon produces over two-thirds of all the grass seed in the world, "which means it's probably also the grass pollen capital of the world," Joshi said.

  • Grass pollen levels peak in May and June, the most prominent times people often feel allergies — with symptoms like sneezing, itchy nose, watery eyes and nasal congestion.
  • Increased pollen levels can also exacerbate asthma symptoms and lead to wheezing, coughing and difficulty breathing for some.

The intrigue: Allergy season in Portland increased by 26 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," Joshi said.

  • It's likely that with more exposure to allergens and pollution, more people are developing allergies over time, he added.
  • Several studies have found that severe allergies can cause more kids to be absent from school and make adults less efficient, resulting in billions of dollars in losses for local economies.

The bottom line: Reduce the amount of allergens you're in contact with 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 you're still suffering, Joshi recommends a steroid nose spray like Flonase over antihistamine tablets.

Get more local stories in your inbox with Axios Portland.


Support local journalism by becoming a member.

Learn more

More Portland stories


Get a free daily digest of the most important news in your backyard with Axios Portland.


Support local journalism by becoming a member.

Learn more