If you think your ragweed allergies are getting worse, you may be right. And global warming may be the culprit, according to the American Academy of Allergy, Asthma & Immunology.

That's not good news for the estimated 36 million Americans who suffer from ragweed allergy, the primary cause of fall allergy symptoms. Ragweed season unofficially begins Aug. 15.

Global climate change is believed to be making ragweed season worse for allergy sufferers. Recent studies suggest that increasing temperatures and carbon dioxide levels are already resulting in longer ragweed seasons and more concentrated pollen counts. The Journal of Allergy and Clinical Immunology (JACI), the official scientific journal of the AAAAI, has devoted its September issue to exploring the effects of climate change on allergic disease - including ragweed allergy.

In a review article to be published next month in the JACI, Richard W. Weber, MD, FAAAAI, and chairman of the AAAAI Aerobiology Committee, writes that "there is now a wealth of evidence that climate change has had, and will have, further impact on a variety of allergenic plants."

Researchers have decisively linked climate change to "longer pollen seasons, greater exposure and increased disease burden for late summer weeds such as ragweed," Weber writes, citing among other findings that increased carbon dioxide has resulted in pollen production increases of 61-90 percent in some ragweed varieties.

According to data from the AAAAI one ragweed plant can produce 1 billion pollen grains in an average season. Due to the grains' light weight, they can travel up to 400 miles with the breeze, leaving virtually no outdoor place ragweed-free.

Allergy shots, or immunotherapy, are effective treatment in up to 90 percent of patients with ragweed allergy. Individuals who suffer from ragweed allergy can also take simple steps to prevent or relieve symptoms:

- Keep windows closed to keep pollen outside homes and cars. Use the air conditioner, which filters, cools and dries air.
- Stay indoors when pollen counts are highest, typically between 10 a.m. and 4 p.m.
- Check daily pollen counts for your area at http://www.aaaai.org.
- Change clothing after time spent outdoors and avoid drying laundry outside.
- Sleep well by taking a shower before bed to wash pollen from your hair and face, preventing it from ending up on your pillow.

Many individuals with ragweed allergy also experience symptoms when eating fresh produce such as bananas, cucumbers, melons and zucchini. This occurs when the body confuses proteins in these foods with similar ones in ragweed.

Given its complications, an allergist/immunologist is the best-qualified medical professional to diagnose and treat ragweed allergy and other allergic diseases.

The AAAAI represents allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic disease. Established in 1943, the AAAAI has nearly 6,500 members in the United States, Canada and 60 other countries.