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PNAS study: Ragweed allergy season longer due to climate change

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PNAS study: Ragweed allergy season longer due to climate change

Jorge Hernandez February 22, 2011

People who live in the northern part of North America are experiencing longer seasons of ragweed allergies, according to a new study published online in the Proceedings of the National Academy of Sciences, reports Bloomberg.

The researchers stressed the effects of climate change on ragweed season.

"This study is a confirmation of what the Intergovernmental Panel on Climate Change has been projecting. We've gone from a theoretical projection of changes in the timing of ragweed season, to boots on the ground starting to see it happen. This is a caution light. Pollen seasons may be getting longer, and climate change may have health implications as well," Lewis Ziska, lead author and plant physiologist at the Agricultural Research Service of the U.S. Department of Agriculture, told the news source.

The study researchers looked at 15 years of data, from 1995 to 2009, including information on pollen counts and weather in 10 different latitudes, ranging from Georgetown, Texas, in the south, to Saskatoon, Canada, in the north, according to the Los Angeles Times.

Pollen season was found to be 27 days longer in Saskatoon, Canada, than it used to be.

"It will be a longer season for those who had shorter seasons. And, pollen levels have increased, too. Not only is the total amount of pollen increased, but the pollen is more potent, too. Patients who have ragweed allergy will suffer more," Dr. Jay Portnoy, chief of Allergy, Asthma and Immunology at Children's Mercy Hospitals and Clinics in Kansas City, Missouri, told BusinessWeek.

At least 10 percent of people in the United States are allergic to ragweed, and the incidence of allergies has increased in the past 30 years, according to the study.