By Thomas D. Schram,HealthSCOUT Reporter

SATURDAY, Sept. 16 (HealthSCOUT) -- To the millions who dread autumn because of their ragweed pollen allergies, there is this disturbing news: Things are only going to get worse.

According to recent reports from the U.S. Department of Agriculture (USDA), the higher carbon dioxide levels brought on by global warming have dramatically increased the amount of ragweed pollen. And projections show future pollen levels are going nowhere but up.

The science is simple: Plants thrive on carbon dioxide and, in return, they give off oxygen.

"It's a very nice symmetry there. Without carbon dioxide, plants wouldn't grow. Life would cease to exist as we know it," says USDA plant physiologist Lewis Ziska, who conducted the research last spring.

But Ziska's research shows there can be too much of a good thing.

Ziska grew ragweed indoors under the carbon dioxide levels of 1900, today and what they are projected to be in 100 years. Pollen production per plant went from 5.5 grams to 10 grams to 20 grams as the carbon dioxide levels moved up the scale.

Those figures are nothing to sneeze at.

"Most everyone associates ragweed with seasonal allergies in the fall, and anywhere from 5 to 15 million people suffer from ragweed allergies, sometimes acutely. So, from a health perspective, it's a big concern," Ziska says.

"We're in a situation right now where the amount of carbon dioxide in the atmosphere is increasing quite dramatically. The problem is that you can't pick and choose which species you want to have stimulated," Ziska says. "It not only stimulates the growth of things like trees and soybeans and wheat, it also stimulates the growth of ragweed and poison ivy and all sorts of noxious things."

So should we be making an effort to eradicate ragweed?

"We should be, but I don't think it's going to happen very soon. It's very ubiquitous. I've seen it everywhere from vacant lots in the cities to edges of the farmers' fields," he says.

"The epidemiology of ragweed allergy is fairly complex. Some of the things that affect sensitivity are things that you would find more in the city than out in a rural area. For example, ground-level ozone is one of the factors which increases your sensitivity to ragweed pollen. Diesel fuel is another," Ziska says.

So what should we do as we move into the heart of ragweed pollen season?

Go quickly to the drugstore, says Dr. Richard Honsinger, a member of the American Academy of Allergy, Asthma and Immunology. "There are lots of medicines that are over-the-counter that you can buy and try," he says.

Honsinger says antihistamines are the first step. Nonprescription ones can cause drowsiness, however. Next, he says, are nasal sprays.

"But don't get hooked on the ones that say decongestant -- the ones for colds -- because they tend to inflame the nose, and they work fine for three or four days and then they start to make you swell and you get worse," he says.

If those fail, see your doctor for prescription drugs that often don't make you drowsy, Honsinger says. Stubborn cases should be referred to an allergist. You'll be tested for sensitivity and started on allergy shots to build up tolerance.

Honsinger says that about 95 percent of those seeking relief from ragweed pollen can be helped.

What To Do

Be aware of developing sensitivity to allergies, says Honsinger. Many people don't develop allergies until their late 20s, and some don't get their first allergy attack until they are in their 70s.

View the National Institute of Health's ragweed pollen page. And read the USDA's bulletin on the increasing ragweed pollen levels.

(From HeaalthSCOUT)