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Release: Immediate

EDITORS: The University of Iowa will provide daily pollen counts beginning Tuesday, August 12, and continuing throughout ragweed season. For daily counts, call the UI pollen count information line at (319) 335-8964.

UI offers daily ragweed allergy forecasts

IOWA CITY, Iowa -- It's that time again. Watery eyes, scratchy throats, runny noses and sneezing mark the beginning of ragweed season, a stretch of late summer dreaded by millions of people with allergies.

Ragweed allergies -- also known as hay fever -- affect nearly 15 percent of Americans. Iowa and other Midwestern states offer ideal conditions for the ubiquitous ragweed plant, which releases its pollen into the air for about six weeks starting in mid-August.

"Every year is a good year for ragweed and a bad year for people with allergies," says Dr. John Weiler, professor of internal medicine at the University of Iowa College of Medicine. "The plant always grows well in Iowa, regardless of weather."

The chief culprits are actually two plants, Ambrosia artemisifolia, or common ragweed, and Ambrosia trifida, best known as giant ragweed or horseweed. Each year, more than 250,000 tons of their microscopic pollen grains are blown about the United States.

Starting Tuesday, August 12, and continuing through the end of ragweed season in late September, the UI College of Medicine will offer daily pollen counts to help people with allergies gauge their symptoms.

A thin, transparent tube atop a building on the UI health science campus collects airborne pollen grains that are measured by researchers. Though daily counts record the amount of pollen detected over the previous 24 hours, they are usually a good indicator of current conditions.

A pollen count of 200 or less is said to fall into the "comfort zone," meaning that most people will be free of allergy symptoms. The "discomfort zone" includes counts from 220 to 1,000, and indicates that most people with ragweed allergy will feel its effects. Counts greater than 1,000 -- the "severe discomfort zone" -- mean serious symptoms in people who are most sensitive to ragweed and milder reactions in those who seldom experience symptoms at lower levels.

Allergies occur when the body's immune system overreacts to an otherwise harmless substance like ragweed pollen. Inhaled pollen adheres to antibodies produced by the body and triggers an immune reaction that causes respiratory symptoms, or allergic rhinitis. During ragweed season, some people allergic to the plant may also react to foods that contain similar proteins, including chamomile, cantaloupe, honeydew and watermelon.

Allergy symptoms can be severe, even incapacitating, and avoiding pollen on the worst days is the best way to prevent symptoms. "If possible, stay indoors in air-conditioned areas, particularly in the early morning when the ragweed plant produces most of its pollen," Weiler says. The safest times to venture outside are in late evening or after a rainfall.

Since ragweed pollen clings to hair and clothes, washing one's hair before bedtime may reduce symptoms, as can frequent vacuuming, dusting, and laundering bedding. Contact lenses can increase eye irritation, so people with ragweed allergies may want to avoid them on heavy pollen days.

Non-prescription antihistamines and nasal sprays may also provide relief, but relying on sprays can bring additional problems. When overused, sprays can cause swelling in the nose and mimic allergy symptoms.

Physicians can prescribe stronger medications for people with the worst symptoms. For more information, consult your physician or other health care provider.