CO2 and Hay Fever (quick hit)

Carbon dioxide may cause hay fever to worsen

By Becki Francis

Higher carbon dioxide (CO₂) levels, which contribute to global warming, may make the fall season worse for those with ragweed allergies.

The U.S. Department of Agriculture released research showing that elevated environmental CO₂ levels can lead ragweed to produce twice as much pollen as in a lower, current level.

Lewis H. Ziska, a plant physiologist with USDA's Agricultural Research Service, performed the research. He counted the pollen on ragweed grown in indoor chambers at various levels of CO₂. The chambers were set at turn-of-the-century levels of 280 parts per million (ppm), today's levels of 370 ppm and future predicted levels of 600 ppm. Pollen production went from 5.5 grams to 10 grams to 20 grams as CO₂ moved through these three levels.

Sneezing, stuffy or runny nose, and itchy eyes, nose and throat are all familiar reminders of ragweed’s effects. Ten to 20 percent of Americans suffer from hay fever, or allergies to ragweed pollen, according to the Asthma and Allergy Foundation of America. While ragweed plants only grow for one season, each plant can produce up to 1 billion pollen grains.

Ziska, conducting his research in collaboration with Johns Hopkins University School of Public Health, Towson University and Multidata Corporation, says this ongoing experiment should show how global warming and higher CO₂ levels might already be increasing ragweed pollen counts.

For more information, visit the USDA press release online at: http://www.usda.gov/news/releases/2000/08/0278.htm.