Asthma triggers are factors or stimuli that provoke the exacerbation of asthma symptoms or increase the degree of airflow disruption, which can lead to an asthma attack.[1] An asthma attack is characterized by an obstruction of the airway, hypersecretion of mucus and bronchoconstriction due to the contraction of smooth muscles around the respiratory tract. Its symptoms include a wide range of manifestations such as breathlessness, coughing, a tight chest and wheezing.[2]
An asthma attack is usually mediated by an inflammatory pathway, where a trigger such as an allergen could lead to a series of immune response mediated by various types of immune cells.[3]
Common triggers for asthma include allergens like pet dander, dust mites, pollens and molds. Other types of triggers like exercise, air pollutants, tobacco smoke, humidity, cold air, or certain medicines may also play a role in triggering asthma.[4] While it has been proposed that asthma triggers can be classified into three types: allergic triggers, environmental triggers and physical triggers, a universal categorization of asthma triggers has yet to be done.[4] Other studies have also classified asthma triggers into psychological factors, air pollutants, physical activity, allergens and infection.[5]
Asthma is an extremely common chronic disease affecting over 26 million people and 7 million children in the US.[3] Recognizing the trigger for asthma and avoiding it can be a simple yet effective way to deal with the disease and avoid an asthma attack.[6] Although a cure for asthma is yet to be invented, various treatment methods are available for both long-term control and immediate relieve of an asthma attack.[7]
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