An allergy is an abnormal reaction of the body's immune system to a substance in the environment that, for most people, causes no immune response. Any substance that causes allergic reactions in some people is called an allergen. Allergens can be normally harmless substances such as pollen, or noxious substances like pesticides.
Allergies are very common, affecting an estimated 50 million Americans. That means at least one in every six people in the U.S. has some type of allergy.
Outdoor allergies (also called seasonal allergic rhinitis or hay fever) are allergies to common airborne particles that are found outside. When inhaled, the allergen causes symptoms that may include a runny nose, congestion, sneezing, and sinus pressure.
Examples of outdoor allergens include mold spores and pollen from trees, grasses, and weeds. Of course, other allergens can be encountered outdoors, such as bee venom and dust for example, but outdoor allergies usually refer to allergies caused by plant material or fungi.
Outdoor allergies tend to occur in the spring, summer, and fall, when plant pollen is more prevalent. People are sensitive to different allergens and people with seasonal allergies may experience symptoms of differing severity that peak at different times of the year. Outdoor allergies also tend to depend on where in the country you live; you may have very severe allergies in one place and almost no symptoms in another.
For some people, outdoor allergies interfere with daily life by causing difficulty sleeping, fatigue, and irritability.
Symptoms often start at a similar time each year due to the presence of pollen from particular plants to which you are allergic. For most people, symptoms of outdoor allergies tend to diminish with age, but the process is very slow, often taking decades to completely resolve.
Outdoor allergy symptoms may mimic a cold, but there are important differences between colds and allergies. Colds are usually accompanied by a low-grade fever and thick yellow or greenish discharge from the nose, while allergies are not. Colds also take a few days to develop after exposure to a cold virus and last up to a week, while allergy symptoms begin immediately upon exposure to an allergen and last as long as exposure to the allergen does.
The main triggers of outdoor allergies are pollen and mold.
What is pollen? Pollen is the microscopic granules that plants produce to fertilize other plants of the same species; they are the plant's male reproductive cells. While several pollen grains together usually appear powdery in texture, most individual pollen grains are smaller in size than the width of a human hair. Pollen grains travel through the air easily and can also accumulate on outdoor surfaces such as patio furniture or cars.
The pollen produced by bright flowering plants rarely causes allergies, while less eye-catching plants like trees, grasses, and weeds often have very allergenic pollen. This is due to the fact that flowing plants rely on birds and insects for fertilization (and the elaborate coloring serves to attract them), thus these plants have large, waxy pollen designed to attach itself to these visitors. Most trees, grasses, and weeds have small, dry pollen that is designed to be spread by the wind and it is these plants that tend to trigger allergy symptoms.
The type of pollen you encounter outdoors depends on the current season and the part of the country in which you live.
The immune system normally protects the body from foreign invaders that can cause harm such as viruses and bacteria. During an allergic reaction, the immune system turns its defenses against a substance that does not normally cause disease, one that is ignored by the immune system of people without allergies, and this causes allergy symptoms.
When a person with outdoor allergies encounters an allergen such as tree pollen, the immune system attempts to protect the body against the "invading" pollen grain, even though the pollen presents no real threat.
Outdoor allergens are likely to be encountered in the nose, eyes, or possibly the lungs, leading to symptoms of inflammation in those areas: sneezing and runny nose or congestion, itchy red eyes, coughing, etc.
Researchers aren't really sure why some people have outdoor allergies while others don't.
In general, allergies have a strong hereditary component meaning you have a greater chance of developing allergies if one or both of your parents has them. However, scientists do not believe that people inherit sensitivity to specific allergens, but instead inherit a general tendency to develop some type of allergy or allergies.
Most people with allergies are allergic to more than one allergen. It is possible that some people have a genetic tendency to develop allergic reactions because they are more likely to produce to IgE antibodies than people without allergies.
A person can develop allergies at any age, whether that person is already allergic to several allergens or if that person has never experienced an allergic reaction to anything.
Other risk factors for developing outdoor allergies include:
The symptoms of outdoor allergies are very similar to those of the common cold so it may be difficult to distinguish between the two.
A good rule of thumb: When cold-like symptoms last longer than one or two weeks, or if you tend to have frequent cold-like symptoms, you may want to consult your doctor to discuss being tested for allergies.
You may also want to consult your doctor about allergies if you notice any of the following:
What to expect at the doctor: When you talk to a doctor about your suspected allergies, he or she will likely give you a physical exam and ask you about your recent history of symptoms as well as your family's history of allergies and asthma. Giving a complete and thorough history is the most important way to find out if your symptoms may be related to allergies. If the doctor suspects you may have outdoor allergies, he or she may conduct allergy testing or may refer you to a specialist for allergy testing. Allergy testing can tell you exactly what allergens you are allergic to, which may help you avoid them in the future.
What are allergy skin tests? Allergy skin tests are usually conducted by an allergy specialist and involve administering a series of possible allergens into scratches made on the arm or back or by injecting them subcutaneously (under the skin). If you are sensitive to a particular allergen, it provokes a small immune response and your skin will become raised and red in the area where it was injected. The size of the raised area determines how sensitive you are to each particular allergen.
The most commonly used treatments for allergies are over-the-counter and prescription drugs.
If you have allergies, the best thing to do is to determine what allergens you are most sensitive to and take measures to avoid them.
If you are allergic to spring pollen, you can minimize your exposure by keeping the windows in your home closed in the springtime. You can also consider using an air purifier with a high-efficiency particulate air (HEPA) filter to help keep outdoor allergens outside of your home. Wash clothes frequently during your sensitive season because clothes you have worn outside can accumulate pollen and mold spores.
Here are some other tips to help you deal with outdoor allergies from the American Academy of Allergy, Asthma, and Immunology:
See a doctor if:
Outdoor allergies in the early spring are often triggered by the pollen of these trees:
· western red cedar
For those with outdoor allergies in the late spring or early summer, pollen from grasses such as timothy, Bermuda, orchard, sweet vernal, red top, and some blue grasses are the main cause. In late summer and fall, ragweed is the most common source of allergenic pollen but other sources include sagebrush, pigweed, tumbleweed, Russian thistle and cockleweed.
For many people, outdoor allergies tend to occur at around the same time every year because plants tend to have a very regular pollination schedule. However, recent weather history and current conditions can dramatically affect the amount of pollen that is present in the air at a given time. Latitude is another major factor in the timing of pollination. In general, pollination seasons start later the farther North you go. In the South, pollen may show up as early as January, while in the Northern U.S. it may not begin until late in April.
The other main cause of outdoor allergies is mold. Mold is a microscopic fungi related to mushrooms that tends to grow in damp places. It reproduces by producing spores, and like pollen, mold spores can travel through the air. Unlike pollen, different molds do not have specific seasons, but the level of mold spores is heavily influenced by weather conditions such as wind, rain, and temperature. Mold spores are present year round in the South and on the West Coast, but in other areas they tend to peak in July in the warmer states and October in the colder states.
Molds are present almost everywhere outdoors, including in soil, vegetation, and rotting wood. Mold can also be found indoors, especially in damp areas such as attics, basements, bathrooms, and inside refrigerators.