IL17A and chronic obstructive pulmonary disease: In 2019, it was shown for the first time that prolonged exposure to PM2.5 alone can cause chronic obstructive pulmonary disease in mice, and long-term PM2.5 exposure increases the expression of proinflammatory cytokines (IFN-γ, TNF-α, IL-17A, IL-6, and IL-8) associated with the condition in the mouse serum and BALF.