Wednesday, September 8, 2010

What is Hay Fever?

What is Hay Fever? | Hay Fever Overview

Hayfever is the common name given to allergic reactions caused by the pollen of a number of different plants. The name comes from the fact that the season when hay is made is also the season where airborne pollen is most predominant in most regions of the world, and so is the time of year when hayfever symptoms are most often seen. There are a number of plants best known for causing hayfever, but virtually any wind-pollinating plant can cause an allergic reaction.

The biggest villains in hayfever each year tend to be grasses, with a wide range of people allergic to some very common grasses. Of note are both timothy grass, or Phleum pratense, and ryegrass, or Lolium sp.. Common weed species are also responsible for some of the worst cases of hayfever each year. Particular nuisances include species like plantain, or Plantago, ragweed, or Abrosia, mugwort, or Artemisia, sorrel, or Rumex, and nettle, or Urticaceae. A number of common trees may also provoke hayfever in sensitive individuals, including willow, poplar, hazel, alder, cedar, and birch.

Hayfever symptoms vary from person to person. Some people may suffer a runny nose or sinus congestion. Others may have itchy eyes and sneezing.

The time of year that hayfever sets in will differ depending on the region, the weather, and what species the sufferer is allergic to. The majority of wind-borne pollinators come into their full pollination sometime beginning in mid-spring and continuing through the summer. Some species, however, may enter full pollination in fall or winter, and some may have extremely short or extremely long windows. Depending on the species one is allergic to, living in the same place may afford the opportunity to predict when hayfever will be particularly bad, allowing a sufferer to prepare through medication, staying indoors, or leaving the area temporarily.

Since the pollen that causes hayfever is carried on the wind, meteorological conditions play a large part in how bad a hayfever season might be for an individual. For example, in damp or wet weather, the majority of pollen will simply be washed away or kept close to the ground, so that a hayfever reaction is unlikely. In cooler weather pollen won’t spread nearly as far, leading to reduced symptoms. On hot, dry days, however, especially breezy days, pollen will spread far and wide, exacerbating hayfever symptoms for all sufferers.

It is easy, as well, to mistake hayfever allergies for simple dust allergies. Often dust allergies become worst in the same environmental conditions as hayfever, making it sometimes difficult to determine what is causing the allergic reaction. At the same time, many people who are allergic to pollen are also allergic to dust, so an onset of hayfever may be a combined reaction to both dust and pollen freely floating in the air.

Treatment of hayfever primarily involves trying to reduce exposure to the pollen that causes the onset of symptoms. The easiest way to do this is simply to stay indoors during hayfever season, especially on the hottest, driest, and breeziest days. Some sort of indoor filter can help immensely, either a filter specifically designed to take airborne particles out of the air, or a simple air conditioner. Regular bathing, washing of clothes, and nasal irrigation can also help eliminate residual allergens. For those who can’t limit their exposure to the allergens, hayfever symptoms can be reduced by taking mediators like antihistamines, which help prevent the worst of the body’s allergic response.

Causes of Hay Fever – Recherche

Causes of Hay Fever – Recherche

Every summer thousands of people in the UK brace themselves for a battle against sore eyes, a runny nose and bouts of sneezing. Hay fever, also known as seasonal allergic rhinitis, is no fun at all. Although these days we have a variety of effective ways to tackle the unpleasant symptoms, it’s still useful to know exactly what the causes of hay fever are.

Hay fever, like all allergic reactions, is caused by allergens, foreign “invaders” that enter your body by inhalation, by swallowing, or through your skin.

    * In hay fever, the allergens are airborne substances that enter your airways (mouth, nose, throat, and lungs) via your breathing and the linings of your eyes and sometimes ears via direct contact.
    * Most of the time it is difficult to identify a specific allergen.
    * Once these allergens come in contact with your airway, the white blood cells of your immune system produce antibodies to the offending substance. This overreaction to a harmless substance is often called a hypersensitivity reaction.
          o The antibody, called immunoglobulin E, or IgE, is stored on special cells called mast cells.
          o When the antibody comes in contact with the corresponding antigen, they promote release of chemicals and hormones called “mediators.” Histamine is an example of a mediator.
          o It is the effects of these mediators on organs and other cells that cause the symptoms of the allergic reaction, in this case hay fever.
          o The most common allergens in hay fever are pollens.
               1. Some species pollinate in the spring and others in the late summer and early fall.
               2. Generally, the farther north a plant is, the later in the season it pollinates.
                + Pollen is small particles released by flowering plants.
                + It is moved around by wind to other plants of the same species, which it fertilizes so that the plant can bloom again.
                + Pollens from certain types of trees, grasses, and weeds (such as ragweed) are most likely to cause reactions. Pollens from other types of plants are less allergenic.
                + The time of year when a particular species of plant releases pollen, or “pollinates,” depends on the local climate and what it normal for that species.

Variations in temperature and rainfall from year to year affect how much pollen is in the air in any given season.

    * The other common allergens in hay fever are molds.
          o Molds are a type of fungus that has no stems, roots, or leaves.
          o Mold spores float through the air like pollen until they find a hospitable environment to grow.
          o Unlike pollen, however, molds do not have a season. They are present throughout the year in most of the United States.
          o Molds grow both outdoors and indoors.
         1. Outdoors, they thrive in soil, vegetation, and rotting wood.
         2. Indoors, molds (usually called mildew) live in places where air does not circulate freely, such as attics and basements, moist places such as bathrooms, and places where foods are stored, prepared, or discarded.
    * The amounts of pollen and molds in the air are measured daily in many areas around the United States and reported by the National Allergy Bureau.
          o The pollen and mold counts at which people develop allergic symptoms vary quite a lot by individual.
          o Pollen and mold counts are not very helpful in predicting how a specific person will react.
    * Risk factors for hay fever
          o Family members with hay fever
          o Repeated exposure to the allergen
          o Other allergic conditions such as eczema or asthma
          o Nasal polyps (small noncancerous growths in the lining of the nose)
    * The allergens that cause symptoms in an individual as he or she ages. Symptoms decrease in some allergy sufferers, but not all, as they grow older.
    * Bodily changes of pregnancy may make hay fever worse.

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