Come late summer, some 10 to 20 percent of Americans begin to suffer from ragweed allergy, or hay fever. Sneezing, stuffy or runny nose, itchy eyes, nose and throat and trouble sleeping make life miserable for these people. Some of them also must deal with asthma attacks.
All this misery can begin when ragweeds release pollen into the air, and continue almost until frost kills the plant.
What Is Ragweed?
Ragweeds are weeds that grow throughout the United States. They are most common in the Eastern states and the Midwest. A plant lives only one season, but that plant produces up to 1 billion pollen grains. Pollen-producing and seed-producing flowers grow on the same plant but are separate organs. After midsummer, as nights grow longer, ragweed flowers mature and release pollen. Warmth, humidity and breezes after sunrise help the release. The pollen must then travel by air to another plant to fertilize the seed for growth the coming year.
Ragweed plants usually grow in rural areas. Near the plants, the pollen counts are highest shortly after dawn. The amount of pollen peaks in many urban areas between 10 a.m. and 3 p.m., depending on the weather. Rain and low morning temperatures (below 50 degrees Fahrenheit) slow pollen release. Ragweed pollen can travel far. It has been measured in the air 400 miles out to sea and 2 miles up in the atmosphere, but most falls out close to its source.
These annual plants are easily overgrown by turf grasses and other perennial plants that come up from established stems every year. But where the soil is disturbed by streams of water, cultivation or chemical effects such as winter salting of roads, ragweed will grow. It is often found along roadsides and river banks, in vacant lots and fields. Seeds in the soil even after many decades will grow when conditions are right.
What Is Ragweed Allergy?
The job of immune system cells is to find foreign substances such as viruses and bacteria and get rid of them. Normally, this response protects us from dangerous diseases. People with allergies have specially-sensitive immune systems that react when they contact certain harmless substances called allergens. When people who are allergic to ragweed pollen inhale its allergens from air, the common hay fever symptoms develop.
Seventeen species or types of ragweed grow in North America. Ragweed also belongs to a larger family called Compositae. Other members of the family that spread pollen by wind can cause symptoms. They include sage, burweed marsh elder and rabbit brush, mugworts, groundsel bush and eupatorium. Some family members spread their pollen by insects rather than wind, and cause few allergic reactions. But sniffing these plants can cause symptoms.
Who Gets Ragweed Allergy?
Of Americans who are allergic to pollen-producing plants, 75 percent are allergic to ragweed. People with allergies to one type of pollen tend to develop allergies to other pollens as well.
People with ragweed allergy may also get symptoms when they eat cantaloupe and banana. Chamomile tea, sunflower seeds and honey containing pollen from Compositae family members occasionally cause severe reactions, including shock.
What Are Its Symptoms?
The allergic reaction to all plants that produce pollen is commonly known as hay fever. Symptoms include eye irritation, runny nose, stuffy nose, puffy eyes, sneezing, and inflamed, itchy nose and throat. For those with severe allergies, asthma attacks, chronic sinusitis, headaches and impaired sleep are symptoms.