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Woe Is Us: Allergies Go Amok

If you're sneezing, coughing, or wiping your nose as you read this, chances are you're one of the 40 million Americans who are allergic to pollen. And if you have the impression that your hay fever is worse than it used to be, you're right. And it's likely to get worse still.

In northern latitudes, global warming has extended the pollen season by as many as 27 days, giving spores from trees, grass, and weeds extra time to irritate your nasal passages, clog your lungs, and dull your brain. The combination of warmer temperatures and higher carbon dioxide levels also seems to supercharge pollen production for certain sneeze-inducing flora, like ragweed, which is responsible for more hay fever than all other plants combined. Climate change allows it to grow in more places and create more pollen. At the same time, increased levels of carbon dioxide seem to make each grain of pollen contain more of the allergens that compel you to sneeze.

Last year, Pittsburgh recorded tree pollen in the air in late February—several weeks ahead of schedule. By March and April, the highest tree-pollen counts ever recorded were being measured in Georgia, Missouri, New Jersey, and Tennessee. Anything over 1,500 grains per cubic meter of air is considered to be very high. On one day in March, Nashville's pollen count reached a record-shattering 16,000.

In a paper presented at the annual meeting of the American College of Allergy, Asthma and Immunology last November, allergist Leonard Bielory predicted that by 2040, pollen counts could be 2.5 times greater than they were in 2000. For anyone with hay fever, that's a truly breathtaking prospect. —D.S.

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