Some people find themselves retreating indoors in late August, not because of the heat and humidity but because of their allergies. In the Northeast, South and Midwest, ragweed begins blooming in mid-August and continues until late October and sometimes longer. This leaves ragweed-allergy sufferers unable to enjoy the fall season.
A Hardy Weed
Ragweed, like other fall allergens such as sage, mugwort, and rabbit brush, usually grows in undeveloped areas such as fields, roadsides, and abandoned lots. But because billions of pollen grains from a single ragweed plant can travel through the air for up to 400 miles, ragweed pollen is found in urban, suburban and rural settings.
"Ragweed is incredibly hardy," says Dr. Christopher Randolph, an associate professor of allergy and immunology at Yale University School of Medicine and a spokesperson for the American Academy of Allergy, Asthma and Immunology (AAAAI). "It can be borne for miles into the air and is found at sea and on every continent."
Sufferers' Symptoms
When someone is allergic to ragweed, the immune system treats the plant's pollen as a foreign invader. First, white blood cells produce IgE antibodies that specifically target ragweed pollen. These antibodies attach themselves to mast cells, which exist in large numbers in the nose, eyes, lungs and digestive tract. When pollen is inhaled, these mast cells release histamine and other chemicals that cause the misery of hay fever: sneezing and an itchy, runny nose.
Copyright 2009 NBC Health
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