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Background: According to epidemiologic studies, fine particulate matter (particulate matter ≤2.5 μm, PM2.5) is closely associated with increases in the incidence and severity of chronic rhinosinusitis (CRS). However, the role of PM2.5 in the pathophysiology of CRS remains largely unknown. In this study, we investigated the effects of PM2.5 on nasal cilia, tissue remodeling, and mucus hypersecretion in a rabbit model of CRS. Methods: CRS rabbits were exposed to ambient PM2.5 via a PM2.5 inhalation exposure system. The degree of ciliary damage was evaluated using scanning electron microscopy (SEM). Histopathologic changes were determined using periodic acid‐Schiff (PAS) staining of goblet cells and Masson trichrome (MT) staining for collagen in the nasal mucosa. MUC5AC expression was assessed by immunohistochemistry. Results: PM2.5 exposure substantially aggravated ciliary disruption in rabbits with CRS. PM2.5 also significantly increased goblet cell hyperplasia and collagen deposition, as reflected by PAS and MT staining. The nasal mucosa of CRS rabbits displayed markedly elevated MUC5AC expression after PM2.5 exposure. Conclusion: Increases in ciliary disruption, nasal remodeling, and mucus hypersecretion may be the pathophysiologic mechanisms underlying the PM2.5‐induced aggravation of CRS. [ABSTRACT FROM AUTHOR]