MONDAY, Feb. 21 (HealthDay News) -- People with ragweed allergies who live in northern climates aren't imaging that their misery is lasting longer and longer each year.
New research suggests that for people living in some northern U.S. states, the length of ragweed season has gotten longer by more than two weeks, and for people living in some areas of Canada, the ragweed season has stretched by nearly a month.
"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," said study author Lewis Ziska, a plant physiologist at the Agricultural Research Service at the U.S. Department of Agriculture, in Beltsville, Md.
"This is a caution light. Pollen seasons may be getting longer, and climate change may have health implications as well," he said.
Ziska's findings are published in this week's online issue of the Proceedings of the National Academy of Sciences.
Ragweed allergies are very common in the United States. At least one in 10 people in the United States is sensitive to ragweed pollen, according to background information in the study. For people who have any type of allergy, about 27 percent have a ragweed sensitivity.
And, the study reports, the prevalence of allergic disease has been increasing in the United States over the past three decades. Exactly why is unclear, but many experts suspect that changes in the global climate may be causing longer pollen seasons, which increase the duration of exposure to allergens.
If this theory were true, said Ziska, then it would make sense that the length of the ragweed pollen season -- which is dependent on warm, but not too hot, temperatures -- would be getting shorter in southern latitudes and longer in northern latitudes.
All rights reserved