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.