MONDAY, Aug. 25 (HealthDay News) -- Add increased suffering for people with ragweed allergies to the list of problems caused by climate change, a new study suggests.

Recent research indicates that increasing global temperatures and carbon dioxide levels are causing longer ragweed seasons and more concentrated pollen counts, says the American Academy of Allergy, Asthma & Immunology, which has devoted the September issue of its Journal of Allergy and Clinical Immunology to examining the effects of climate change on allergic disease.

In one of the articles, Dr. Richard W. Weber, chairman of the AAAAI Aerobiology Committee, wrote that "there is now a wealth of evidence that climate change has had, and will have, further impact on a variety of allergenic plants."

Climate change has been linked to "longer pollen seasons, greater exposure and increased disease burden for late summer weeds such as ragweed," Weber noted. Researchers have found that increased carbon dioxide has boosted pollen production by 61 percent to 90 percent in some types of ragweed.

Ragweed pollen grains can travel up to 400 miles with the breeze, which means there is virtually no outdoor location that is free of ragweed pollen.

Allergy shots (immunotherapy) provide effective treatment for 90 percent of people with ragweed allergies, according to the AAAAI, which offered a number of simple steps that can help prevent or relieve ragweed allergy symptoms:

• Keep windows closed in your home and car. 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.
• After you spend time outside, change your clothes. Don't dry laundry outside.
• Take a shower before bed to wash pollen from your hair and face. Otherwise, the pollen could end up on your pillow.

More information

The American Academy of Allergy, Asthma & Immunology has more about allergies.