Which of the following is considered an airborne trigger of asthma?

Airborne triggers of asthma include substances that can be inhaled and lead to an asthma episode. Pollen is a well-known allergen that is carried by the wind, making it a significant airborne trigger for many individuals with asthma, especially during certain seasons when plants release their pollen. When inhaled, pollen can provoke an inflammatory response in the airways, leading to symptoms such as wheezing, coughing, and shortness of breath.

While exercise, weather changes, and food allergies can also affect asthma, they do not fall under the category of airborne triggers. Exercise is known to trigger asthma symptoms in some individuals, particularly when performed in cold, dry air, but it is not an airborne substance. Weather changes can influence asthma indirectly, as they may impact other airborne allergens. Food allergies cause reactions that are typically not related to airborne exposure, as they require ingestion rather than inhalation. Therefore, pollen is specifically classified as an airborne trigger, making it the correct answer in this scenario.