Outdoor allergens are normally harmless substances that trigger symptoms in people who suffer from certain allergies and allergic asthma. Typical outdoor allergens include tree, grass and weed pollen and moldspores. Usually inhaled, these triggers generate symptoms such as sneezing, coughing, runny nose and sore throat, as well as itchy and runny eyes. In some people, they can also trigger an asthma attack.
Outdoor allergens are most likely to trigger symptoms in those with allergic rhinitis. Commonly known as hay fever, allergic rhinitis is an inflammation of the inner lining of the nose that occurs when an allergic individual encounters certain airborne allergens.
A physician can use allergy tests to help pinpoint which outdoor allergens trigger a patient’s symptoms. Once these allergens have been identified, the best way to prevent symptoms is to limit exposure to the allergens as much as possible. People with outdoor allergies may be advised to stay indoors on days with high pollen counts or mold counts and keep windows and doors closed.
People with a family history of allergies are more likely to react to outdoor allergens, particularly those people with other allergy-related conditions, such as eczema and asthma. The best way to treat such reactions is to limit exposure to outdoor allergens to the greatest extent possible.
About outdoor allergens
Outdoor allergens are substances that trigger symptoms in individuals with certain allergies and asthma. Pollen and mold are the most common outdoor allergens, but there are many other allergens present outdoors.
These allergens usually gain access to the body through the nose (inhaled) and trigger symptoms of allergic rhinitis (inflammation of the inner lining of the nose due to contact with an allergen). However, they can also enter by ingestion (eaten) or skin contact (touched) and trigger various other symptoms.
In people with allergies or allergic asthma (an allergic inflammation in the lower airway of the respiratory system), the body mistakes these harmless substances as “foreign invaders” and creates antibodies (proteins that attach to foreign substances and help destroy them) to defend against them. This process, called an allergic cascade, leads to the symptoms associated with allergic reactions.
Allergens carry proteins that trigger symptoms in allergic individuals. Outdoor allergens that carry these proteins include:
- Pollens. Small, powdery grains of flowering plants that can easily become airborne. These are most often produced by trees, grass and weeds. Many plants carry pollens that can trigger allergies, but ragweed is the most common. In fact, 75 percent of people with seasonal allergies are allergic to ragweed, according to the Asthma and Allergy Foundation of America.
- Molds and mildews. Tiny fungus spores that can become airborne. These often thrive outdoors in soil, vegetation and rotting wood. They can be found indoors as well, especially in damp areas, such as basements and bathrooms.
Because the airborne levels of pollen and mold change with the seasons, allergic individuals are more likely to experience symptoms during specific times of the year. Reactions to outdoor allergens usually flare up in the spring when plants begin to bloom and release pollen. Some trees begin to pollinate as early as January in the southern United States and February in the northern states. By late spring, grasses are pollinating – followed by weeds in the summer and fall. Warmer climates will see outdoor mold spore growth peak by midsummer.
A person’s symptoms can also vary day-to-day or within the same day depending on the weather. Allergy symptoms are often minimal on rainy, cloudy or windless days because pollen does not move around during these conditions. However, hot, dry and windy weather results in increased allergy symptoms due to greater pollen and mold distribution. Pollen counts also tend to be lowest in the evening hours and highest in the mornings.
Though most outdoor allergens vary by season, there are certain locations where pollen or mold is present all year. Therefore, people in these areas may have outdoor allergies that are perennial (symptoms occur year-round). However, it is much more common for people with perennial allergies to be allergic to indoor allergens than for outdoor allergens to trigger year-round symptoms.
Related allergies and conditions
Outdoor allergens are most likely to cause symptoms in individuals with the following conditions:
- Allergic rhinitis. Commonly called hay fever, allergic rhinitis is an inflammation of the inner lining of the nose that occurs when an allergic individual encounters an airborne allergen such as pollen or mold. Symptoms include sneezing, coughing, runny nose, sore throat and itchy or watery eyes.
- Asthma. A chronic inflammation of the body’s bronchial (airway) tissues that afflicts millions of people in the United States. People with asthma experience shortness of breath, chest tightness, coughing and wheezing (a whistling or high-pitched sound that results when breathing tubes are narrowed or obstructed). These symptoms intensify during an asthma attack, which occurs when exposure to allergens or other stimuli further inflame the airways, leading to an inability to expel trapped air from the lungs.
- Allergic conjunctivitis. An allergic reaction of the eye to an allergen such as pollen or mold. It involves an inflammation of the clear membrane that covers the white of the eye (conjunctiva) and can result in itching, burning, and redness in the eye. Swollen eyelids, watery eyes and eye discharge also are symptoms of allergic conjunctivitis.
- Vernal conjunctivitis. A sight-threatening inflammation of the membrane covering the back of the eyelid (tarsal conjunctiva). It primarily affects children younger than 14, and at least twice as many boys as girls have the condition. Allergens that come into contact with the eye are believed to be at the root of the condition. It affects both eyes (bilateral) and occurs most often in hot, dry climates during the spring and summer.
- Allergic sinusitis. An allergy-triggered inflammation and infection of the mucous membranes lining the paranasal sinuses (air-filled pockets found within the bones of the nose and face). Allergic sinusitis is usually triggered by allergic rhinitis or a fungus allergy.
Other allergies related to outdoor allergens include:
- Indoor allergies. Molds, pollens and other outdoor allergens are easily tracked indoors through normal human activity. Pets can also carry these allergens into home in their fur. Outdoor allergens can also enter a home through open windows. Therefore, it is common that outdoor allergens become indoor allergens – and even become a part of household dust. Once indoors, allergens can remain for months, past their “season” as outdoor allergens. This can lead to perennial (year-round) symptoms.
- Cosmetic allergies. In sensitive people, allergic skin rashes can be caused by contact with products designed for outdoor use, such as sunscreen or bug spray.
- Insect allergies. Exposure to most insects capable of triggering allergic reactions in sensitive people occurs outdoors. Venom released in the stings of bees, yellow jackets, hornets, wasps and fire ants can trigger a rare, potentially life-threatening allergic reaction called anaphylactic shock in sensitive people.
- Plant rashes. Contact with certain outdoor plants can cause allergic or irritant skin rashes in many people. Poison ivy is possibly the best known plant to cause allergic reactions, but others include lilies and stinging nettles.
- Pollution. Pollution can be especially dangerous for those who have allergies, asthma and other respiratory disorders. The irritants in pollution can easily trigger symptoms of an allergic reaction or asthma attack.
Signs and symptoms of outdoor allergies
Outdoor allergens often trigger swelling in the sinuses (air-filled pockets found within the bones of the nose and face) and in the passage leading from the throat to the middle ear. Because of this, the most common symptom associated with outdoor allergens is frequent and prolonged sneezing. Other common symptoms may include:
- Itchy and runny nose
- Redness, swelling and itching of the eyes
- Itchy and sore throat
- Ear infections and itchiness in the ears
- Sinus infections
In some cases, outdoor allergens can cause anaphylaxis, which is an allergic reaction that involves two or more body systems. Anaphylaxis can lead to the potentially life-threatening anaphylactic shock which involves a dangerous drop in blood pressure and breathing difficulties.
The symptoms related to outdoor allergens often vary in severity depending on the individual and the environment. However, they will usually last throughout an entire season (with seasonal allergic rhinitis) or throughout the entire year (with perennial allergic rhinitis). The most severe cases are considered extremely uncomfortable and can make it difficult to carry out even normal everyday tasks.
Diagnosis and treatment of outdoor allergies
When a reaction to an outdoor allergen is suspected, the first step toward a diagnosis is usually a physical examination and complete medical history. Obtaining the patient’s medical history is important because the presence of other allergies, asthma or eczema (an itchy, noncontagious inflammation of the skin characterized by a patchy rash that is red, inflamed, dry and scaly) raises the likelihood of a person having reactions to outdoor allergens. A family history where allergies are common is another factor that predisposes a person towards outdoor allergies. A physician will take many other factors into account, such as the nature of symptoms and the time of year they occur.
A physician is also likely to administer allergy tests to pinpoint troublesome allergens. The most common method of identifying allergens is skin testing, but blood tests and x-rays or other types of imaging tests may be performed as well. Skin testing involves introducing a small amount of an allergen to the patient’s skin. The skin is then monitored for signs of a reaction. If a positive skin reaction to that allergen is detected, an allergy is likely.
The best way to minimize symptoms related to outdoor allergens is to follow a strategy of avoidance. In this strategy, the patient tries to minimize exposure to allergens that provoke a reaction.
Though avoidance is the best strategy for treating allergies, it does not work for everyone. In such cases, other treatments may be necessary. Although there is no medication available that can cure allergies, there are several types of medication (e.g., antihistamines, decongestants) available to address symptoms triggered by outdoor allergens. Some medications are taken after the allergic reaction has occurred, to relieve symptoms. Others can help prevent the onset of symptoms.
Allergy shots are one form of treatment that can prevent allergy symptoms from occurring for long periods of time. When using this type of immunotherapy, a person is gradually exposed to increasing amounts of a diluted allergen, administered through regular injections over a period of weeks or months. The goal is to build up enough of a tolerance to the allergen so that symptoms are significantly reduced. This treatment method may be recommended for patients whose symptoms fail to respond to allergy medication, or those who experience symptoms for many months during the year.
Prevention methods for outdoor allergens
The most effective way of controlling allergy symptoms is avoidance. By controlling the environment and minimizing exposure to known outdoor allergens, an individual can greatly limit the number and severity of allergic reactions. Though this treatment method is not easy, there are several basic steps that can prevent contact with the pollens or molds that trigger symptoms. These steps include:
- Stay indoors as much as possible during the pollen season (high pollen counts), and windy and humid days.
- Minimize outdoor activity between sunrise and late morning (the time of day pollen levels are the highest).
- During allergy season, try to keep windows and doors closed at home and in the car.
- Use air conditioning in the home and car, which cleans and dries out air.
- Avoid yard work that could stir up pollen and molds – such as mowing the lawn or raking leaves.
- Avoid hanging laundry outdoors to dry because pollen can collect on fabrics.
- Wash pets frequently to minimize the amount of outdoor allergens that adhere to their skin and coats.
- Shower frequently to wash airborne allergens from hair and skin.
Questions for your doctor on outdoor allergens
Preparing questions in advance can help patients to have more meaningful discussions with their physicians. Patients may wish to ask their doctors the following questions regarding outdoor allergens:
- Do my symptoms indicate outdoor allergies?
- What tests will you use to determine if I suffer from outdoor allergies?
- What allergens may be triggering my symptoms?
- What treatment options are available to me? How effective are they?
- Am I a candidate for allergy shots?
- What steps can I take to minimize exposure to outdoor allergens?
- Will I experience symptoms year-round or only during certain seasons?
- Where can I find the pollen and mold report for our area?
- Will the weather affect my allergies?
- Are my children likely to have outdoor allergies as well?