Raleigh hit 2 new tree pollen highs this year. Here’s how climate change factors in.

No, you’re not imagining it.

Over roughly the last week, Raleigh has recorded two separate tree pollen levels higher than any recorded since 1999. That’s showing up on car hoods, on sidewalks and in allergy medication prescriptions across the region.

The News & Observer talked to some experts about what could be driving those high levels, their impact on people who suffer from allergies and about the role climate change could be playing. Here’s what they told us.

How high have pollen levels been?

Last week saw the two highest tree pollen counts since North Carolina began measuring them in 1999.

N.C. Department of Environmental Quality officials reported that the count of 16,284 tree pollen grains on April 1 was a record high. DEQ also said the count of 11,340 tree pollen grains on April 3 was the second-highest ever recorded.

Those included high levels of pollen from ash, mulberry, oak, pine and sweet gum trees, according to DEQ.

The previous high was 10,995 pollen grains recorded on April 6, 2010.

It’s worth noting that DEQ’s Pollen Lab did not report levels on April 2 or April 4 due to what it called “sample collection error.”

Why were last week’s levels so high?

Robert Bardon, the assistant dean of Extension at N.C. State’s College of Natural Resources, said a mixture of warm temperatures, high winds and humid conditions in the midst of pollen season all came together to generate this week’s record-high pollen levels.

“It was windy, so pollen was all stirred up in the atmosphere,” Bardon said. “But when there’s a lot of humidity, pollen grains kind of swell and then they can burst, which adds then more pollen particles in the air.”

Could climate change be shifting pollen seasons?

Dr. Edwin Kim, the chief of pediatric allergy and immunology at the University of North Carolina, told The News & Observer he’s noticed patients coming in with symptoms from tree pollen earlier in the spring over the last decade or so.

“Where we might have been talking about preparing for allergy season in the very tail end of February, beginning of March, now we’re easily starting to see the earliest signs of pollen in the first, second weeks of February,” Kim said.

On the other end of the calendar, warmer winters mean that the fall weed pollen season can linger longer due to warmer temperatures.

“Especially in the North Carolina area at least we used to have a couple of months of cold with not a lot of pollen, but now that period of time without pollen is shrinking and the seasons clearly are lasting longer,” Kim said.

Climate Central, a climate communications nonprofit, reported that Raleigh’s growing season — or consecutive days without a freeze — has extended by an average of 31 days since 1970, going from about 190 days to just over 220 days.

What about grass pollen?

Tree pollen season is typically followed quickly by grass pollen season, and that’s true with this year’s early starts, according to the N.C. State Climate Office.

Like their tree counterparts, grass started releasing pollen weeks earlier than usual this year, Corey Davis, the assistant state climatologist, wrote in a recent post. Grass pollen levels started to increase on March 1, Davis wrote, much earlier than the typical late March or early April.

Then, Davis wrote, rains in early March helped the grass grow more quickly and release pollen, leading to the two highest levels of grass pollen in March recorded since 2006.

“That extra time allows for more overall pollen production, and when the weather lines up, it can make for more extreme allergy-aggravating days as we’ve seen over the past month. That’s nothing — or, perhaps, something — to sneeze at,” Davis wrote.

How much longer will this spring’s pollen season last?

Pine trees are likely going to stop releasing pollen spores soon, Bardon said, pointing to temperatures. That means it could be save to spray down your deck or wash your car for good this weekend.

Hardwood trees will follow slightly behind that, Bardon added, likely wrapping up their pollen production in early or mid-May.

How could pollen seasons change in the future?

A 2022 study from University of Michigan researchers found that higher temperatures at the end of this century could mean that tree pollen season starts 10 to 40 days earlier than it does now, with weeds and grasses pollen lasting between five and 15 days longer in the fall.

That research also found that the potential daily high of pollen releases could increase by 35% to 40% due to higher temperatures and humid conditions, an exacerbated version of what Raleigh saw last week. And total annual pollen production could increase by 16% to 40%.

“While pollen is one of the main causes of human allergies, these projected future changes may lead to growing population’s exposure and the severity of symptoms in individuals with allergic rhinitis and allergic asthmas induced by pollen,” Yingxiao Zhang and Allison Steiner wrote in the 2022 paper, which was peer-reviewed and published in Nature Communications.

Zhang and Steiner also warned that if carbon dioxide emissions continue to accumulate, pollen emissions could increase dramatically by the end of the century because of a link between carbon dioxide and pollen production.

The most likely change is pollen seasons that start sooner than expected for trees and that potentially linger into the fall or even winter for weeds, Bardon said.

“With warmer temperatures, what I think we’re seeing is that pollen production’s going to start sooner and potentially we get to maximum production earlier,” Bardon said.

Loblolly pines, for example, typically begin releasing pollen after what is called 300 degree days. That means when the number of degrees above 55 degrees Fahrenheit totals 300. When that number reaches 640, the trees are typically releasing the most pollen

Bardon, who has been measuring this over the last decade, said he’s noticed that’s coming earlier, just as Kim has noticed it in the people who are showing up with allergy symptoms.

“The start of pollen season is trending to earlier,” Bardon said.

Those longer seasons could also affect plants, Bardon added, increasing the risk of a hard freeze that damages crucial plants that might have already started growing with earlier warmer temperatures. And the longer growing season could also mean more insects, with the warmer temperatures meaning more life cycles

“Many of our insects, even ones that are native to the area can end up having more life cycles so more broods come on,” Bardon said.

How can people help themselves?

There are two ways to protect yourself from pollen if you are susceptible to allergies or have asthma, Kim said.

The first is to avoid contact with pollen.

That means keeping windows closed to keep pollen outside; washing your hair or shoes after being outside for an extended period of time to keep pollen from coming inside; or washing pets off if they’ve been playing outside.

But, Kim said, it’s virtually impossible for avoidance to be totally effective “without just locking yourself indoors.”

Instead, Kim recommended that people who are susceptible to allergies or who have asthma should stock up on nose sprays, tablets or eye drops before the season really begins, in order to stave off the worst impacts.

“Waiting until you’re in a full-blown asthma or allergy flare, it’s much harder for the treatments to get those back under control,” Kim said.

That could mean a patient needs to see their allergist by the first week in February, particularly if the spring pollen season begins around the middle of the month, Kim added.

A more permanent option is allergy shots, an approach Kim has taken to cure his own allergies. With shots, people need to take regular doses, often over four or five years, to not only address symptoms but potentially do away with the allergy altogether.

“For the patients who can successfully do it, it can be a game changer,” Kim said.

This story was produced with financial support from the Hartfield Foundation and Green South Foundation, in partnership with Journalism Funding Partners, as part of an independent journalism fellowship program. The N&O maintains full editorial control of the work. If you would like to help support local journalism, please consider signing up for a digital subscription, which you can do here.