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Allergies Health Center

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Spring Allergies Strike Early This Year

Experts Say Tree Pollen Season May Be Long and Painful

Spring Allergies Strike Mid-Winter continued...

Biologists say an early pollen season may also mean a long one, though that’s more difficult to predict since the length of the season will depend on precipitation.

After the trees start blooming, rainfall determines how long they keep shedding pollen.

“There are some years that our pollen has come and gone very quickly because it’s been warm and dry,” says Kim Coder, PhD, a professor of tree biology at the University of Georgia, in Athens.

“When you have rainy, intermittent weather, that can prolong the tree pollen season because it lengthens the time the flowers are open and producing pollen,” Coder tells WebMD.

Pollen Seasons Getting Longer, More Severe

Researchers say the early allergy season isn’t a fluke. It may be part of a larger trend that’s being shaped by climate change.

A 2010 study that looked at 26 years’ worth of pollen counts for five allergens in northern Italy showed that as temperatures increased, pollen seasons stretched in that region by more than two weeks. Pollen counts were higher, too. Scientists saw about 25% more pollen in 2007 than they did in 1981. And there was evidence that more people were becoming sensitive to those allergens over time. It’s happening in this country, too.

“We’re seeing a very consistent change in how early plants flower in the spring,” says Lewis Ziska, PhD, a research plant physiologist at the USDA’s Crop Systems and Global Change Laboratory in Beltsville, Md.

What’s more, the warmer temperatures are affecting all plants, not just trees.

Ziska has been tracking ragweed, a plant that is usually a problem in the fall. In a study published last year, he found that ragweed seasons were getting longer in the U.S. and Canada, with northern regions seeing the biggest increases. In Minneapolis, for example, the ragweed season was about 16 days longer in 2009 than it was in 1995. In Saskatoon, Canada, it was nearly a month longer in 2009 than in 1995.

“We really need to kind of sit back, take notice of it, and say, ‘This is something we need to pay attention to,’” Ziska says.

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