Global Warming May Worsen Hay Fever

W A S H I N G T O N, Aug. 16 -- Allergy sufferers, beware: Global warmingcould bring more hay fever, according to government research thatshows ragweed produces significantly more pollen as carbon dioxideincreases.

The ubiquitous weed makes nearly twice as much pollen now as itdid 100 years ago and will likely double its production again overthe coming century with predicted increases in carbon dioxidelevels, the Agriculture Department study suggests.

“This research may help us better understand the troublingimpact of high carbon dioxide levels on our environment and ourhealth,” Agriculture Secretary Dan Glickman said Tuesday.

About 15 percent to 20 percent of the population has hay fever — or allergic reactions to plant pollen, dust and other airborneparticles — and ragweed is the major cause of the problem in thefall.

Grains Travel Many Miles

The plant is found all over the country and is particularlyprevalent in the Northeast and Midwest. The pollen grains are sosmall that they can travel many miles.

A laboratory study done by USDA in 1998 and 1999 found thatragweed pollen counts went from 5.5 grams per plant atcarbon-dioxide levels that existed in 1900 to 10 grams at currentlevels. At predicted carbon dioxide levels in the year 2100, the pollen countwould reach 20 grams per plant.

Results of USDA’s lab study are to be published in an upcomingissue of World Resource Review, a journal of climate-change issues.

More Study Necessary

Scientists at Harvard University are doing similar research thisyear.

“This is a pretty good first sign” that climate change will bea problem for allergy sufferers, said Cynthia Rosenzweig, a seniorscientist at Columbia University’s Center for Climate SystemsResearch.

Many scientists believe a warming of the Earth has been underway for a century and has accelerated over the past 20 years. Thewarming has been linked to a “greenhouse effect” caused bymanmade pollution and increased concentrations of carbon dioxide inthe atmosphere.