(NEW YORK) -- With record pollen counts already on the board for August, this fall is gearing up to be one of the worst, and longest, allergy seasons yet, according to experts.
Thanks to a particularly wet summer, ragweed pollen levels are surging and standing water left over from summer flooding and Hurricane Irene has increased the amount of mold, a common year-round allergen, in the air.
"We're going to have an allergy double whammy," says Dr. Clifford Bassett, medical director of Allergy and Asthma Care of New York.
To top it all off, the allergy season is expected to last a few weeks longer than usual this year, according to research published earlier this year in the Proceedings of the National Academy of Sciences.
While spring allergies usually come from pollen from trees and grass, fall allergies are caused almost exclusively by ragweed pollen. The season usually runs from mid-August until the first frost of the year, around early October, but if the frost is delayed, as is predicted for this year, the allergy season goes on indefinitely until it comes.
For many years, the allergy seasons have been "getting longer and longer ... partly due to global warming," says Estelle Levetin, chairwoman of the aerobiology committee for the American Academy of Allergy, Asthma and Immunology.
"As we're seeing warmer and warmer weather, the fall gets warmer and longer and the effect is that there's no frost to kill the ragweed and end the allergy season," she says.
Rising temperatures have produced a similar lengthening of the spring allergy season, which is now starting about a month earlier than it did decades ago, she says.
Climate change isn't only affecting the length of the allergy season, it's affecting the severity.
"A single ragweed plant produces a million pollen grains, but if you expose it to greenhouse gases, it produces three to four times that much," says Bassett. "So you have climate change making for a longer season, more plants and more potent pollen. It's like a perfect storm," he says.
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