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 mold spores. 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.