Spring Awakening.(seasonal allergic rhinitis)

Byline: editor: Abigail Walch

Sneezing, sniffling, itchy eyes--it's allergy season, and more and more adults are suffering the consequences. Ginny Graves talks with leading scientists about the rush to find answers.

Environmental changes seem to be blamed for everything these days, from cannibalistic polar bears to less flavorful Pinot Noir grapes. And there's a new climate-related concern that could make you even more miserable than a so-so Pinot: seasonal allergies, an affliction that, conventional wisdom holds, starts in childhood. But itchy eyes and sneezing are affecting an increasing number of adults in the United States--an estimated 45 million, according to a recent survey--including many who used to breeze through the season Kleenex-free. Although no one can say for sure how much the problem has grown--the phenomenon is so recent it hasn't been studied in depth--anecdotally, many allergists say they're seeing more and more patients, particularly women, in their 30s, 40s, and 50s, and the drove of new sufferers is spurring scientists to investigate cutting-edge solutions.

"All types of allergies--food, respiratory, and seasonal--are increasing these days, and they're hitting people of all ages, not just kids," says Clifford Bassett, M.D., vice chairman of the public-education committee for the American Academy of Allergy, Asthma & Immunology. The surge is probably due to a number of factors, including our well-known obsession with cleanliness and killing germs, which means we're exposed to fewer microbes--bugs that can make us sick but also keep our immune systems functioning normally.

THE GREEN CONNECTION

The latest suspect behind seasonal sneezing is rising levels of carbon dioxide, a greenhouse gas that is affecting plants and trees in ways no one predicted. When researchers at Harvard University grew allergy-causing ragweed under two conditions--current levels of carbon dioxide and double that (the amount that could be in the air by mid-century)--they found that the plants exposed to more CO2 grew 10 percent bigger but produced 60 percent more pollen, a finding that could account for the fact that real-world pollen counts are soaring.

"Health officials typically issue warnings when the count is about 150 grains per cubic meter, but we're seeing levels in the thousands, especially in cities, which have higher levels of CO2," says Paul R. Epstein, M.D., associate director of the Center for Health and the Global Environment at Harvard Medical School. "The more pollen, the more allergies. It's pretty simple."