The Washington Post

Walter Reed: Tree pollen seems to have peaked

Oak pollen under the microscope (Walter Reed Army Medical Center)

We welcome the cooler temperatures and chance of rain to wash some of that pesky pollen out of the air. The rain will wash the pollen off outdoor surfaces, preventing some additional re-circulation on windy days. The pollen grains do tend to be somewhat sticky and like to adhere to surfaces, hair and clothes. Expect trees to remain HIGH with return of sun and warm temperatures over the weekend.

Warm, sunny days with strong breezes are a worst case scenario this time of year for those allergic to tree pollen. Thankfully we have had cooler weather and rain in between some of those warm, sunny 80 degree days. We have had an up and down type of season.

. . . Our previous two years, 2009 and 2010, were rather frightening with high count days over 4000 grains/cubic meter of air. This year we seem to have reached our peak day at just over 2300 grains/cubic meter of air on 18th April.

Currently, our tree count has dropped again, although still HIGH, at 466.13 gr/cubic meter. Grasses are LOW at 1.6 gr/cubic meter, dock/sorrel is LOW at 0.32 gr/cubic meter and mold spores remain LOW at 927.13 spores/cubic meter of air.

While tree pollen seems to be leveling off or even on its way down, grass pollen peaks in late May or early June said Kosisky. And then there’s ragweed season in the fall...

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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