Air pollutants comprise a complex mixture of airborne particles such as gases, liquids, and particulate matter (PM). Particulate matter 2.5 (PM2.5) refers to fine particles with aerodynamic equivalent diameter less than or equal to 2.5 μm in ambient air. It is one of the most harmful air pollutants that can be deposited in bronchi and alveoli through inhalation. Moreover, PM2.5 can even penetrate the air-blood barrier into the blood circulation. Epidemiological studies have shown a relationship between PM2.5 exposure and adverse health outcomes, including respiratory diseases, cardiovascular diseases, type 2 diabetes, and autoimmune diseases. Nevertheless, the mechanisms underlying PM2.5-induced airway inflammation remain largely unexplored.