CXCL8 and asthma: Studies, such as that by Yan et al. [47], have demonstrated that exposure to PM2.5 can lead to an upregulation of IL-8 expression in both respiratory epithelial cells and macrophages, which indicates a mechanism through which air pollution exacerbates pulmonary inflammation and potentially contributes to the development of respiratory conditions such as asthma and COPD [48].