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Expect Those Allergies to Get Worse


WebMD Health News
Reviewed by Gary D. Vogin, MD

March 28, 2002 -- Whether you're one of the millions already sniffling and sneezing, or you've never yet been bothered by seasonal allergies -- just wait. A Harvard study shows that global warming is directly affecting pollen production. And as our atmosphere becomes clogged with carbon dioxide, plants are responding by putting out more allergens.

"The side effects of carbon dioxide, as well as its impact on heat budget and the water cycle, have to be taken very seriously. This study can help us understand the true costs of burning fossil fuels," says study leader Paul Epstein, MD, director of Harvard Medical School's Center for Health and the Global Environment, in a news release.

Epstein and colleagues grew ragweed plants from seeds in two different enclosed environments. The first mimicked today's atmosphere, with 350 parts carbon dioxide to a million parts air. The second anticipated what the atmosphere will be like in the not-too-distant future, if global warming continues at its current pace -- 700 parts carbon dioxide to a million parts air.

The ragweed plants grown in the futuristic atmosphere put out 61% more pollen than those kept grown in today's air. And more pollen means more allergies and asthma.

"Our observation that a doubling of the atmospheric carbon dioxide concentration markedly stimulates ragweed pollen production suggests that the incidence of hay fever and related respiratory diseases may increase in the future," the researchers write in their report. "These results suggest that there may be significant increases in exposure to allergenic pollen under the present scenarios of global warming."

Additional studies may help public health officials accurately determine the growing threat of hay fever and respiratory diseases such as asthma and find ways to alleviate or prevent them, they say.

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