Allergy season is starting again, and doctors say it will be tougher than last year, CNN reports.
"Pollen levels are increasing, pollen seasons are getting longer, and more people are developing allergies," says Estelle Levetin, Ph.D., chairwoman of the aerobiology committee for the American Academy of Allergy, Asthma & Immunology, as reported by CNN.
A new study suggests this year's allergies will likely last up to 27 days longer than average in the northern regions of North America, even going into November, according to CNN.
Global warming can be blamed for the increase in allergy length, says Jeffrey G. Demain, M.D., director of the Allergy, Asthma & Immunology Center of Alaska, as reported by CNN.
When the temperatures rise due to global warming, plants and trees flower and release pollen earlier each spring. In the fall, they delay the death of ragweed plants from frost, extending the pollen season, Levetin tells CNN.
Higher amounds of carbon dioxide is making pollen more potent, too, CNN reports.
"There's more allergen now in each grain than there used to be," Demain tells CNN.
Thanks to these variables, the number of Americans with allergies is two to five times higher now than it was about 30 years ago, according to surveys from the National Institutes of Health, as reported by CNN.
