The Washington Post

Tree pollen high, but may not have peaked

Close-up of tree pollen under microscope Close-up of tree pollen under microscope (U.S. Army Centralized Allergen Extract Laboratory)

Although somewhat of a late bloomer, spring has hardly spared the D.C. region’s allergy sufferers from the annual bout of sneezing, wheezing and coughing.  Tree pollen counts in the last two weeks have consistently shot up into the high range, and could spike higher.

Today’s tree count, measured by the U.S. Army Centralized Allergen Extract Lab, surged to the high level of 1394.89 (grains/cubic meter) and would have been higher had it not rained this morning, says Susan Kosisky, the lab’s director.

Weather conditions have politely conspired to hold back pollen levels this spring.

“The cooler weather this March and intermittent warm and cool periods for the beginning of April (some with showers) has made it difficult for the trees to really get going,” says Kosisky.

But if you’re miserable from the recent tree counts over 1,000, consider most recent years have seen peaks over 2,000, and 2009 and 2010 both experienced peak counts over 4,000. This year’s highest count so far? 1403.20 this past Tuesday.

(U.S. Army Centralized Allergen Extract Laboratory)
(U.S. Army Centralized Allergen Extract Laboratory)

Last year at this time, due to the unusually warm weather in March, we had already endured the worst of the tree pollen wrath.  The tree count surged to 2,124 on March 28, 4 weeks ahead of average.  Counts began to decline in early April.

Related: Tree pollen spikes to March record high (from 2012)

(U.S. Army Centralized Allergen Extract Laboratory) (U.S. Army Centralized Allergen Extract Laboratory)

In contrast, this year’s peak may coincide with the long-term average, which is just around the corner.

“We are not quite at our peak period just yet, with the last week in April being the overall “peak week” for our tree pollen season,” Kosisky says.

She adds: “Area tree species would love a string of warm, dry sunny weather to release abundant amounts of pollen into the air and send the counts soaring. For allergy sufferers however… a rain dance!”

Jason is the Washington Post’s weather editor and Capital Weather Gang's chief meteorologist. He earned a master's degree in atmospheric science, and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association.
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Jason Samenow · April 18, 2013

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