Second, the observed positive correlation between PM2.5 and the acute-phase ITIH4 protein corroborates our prior findings, highlighting ITIH4's relevance in prolonged PM exposure and its potential involvement in the pathogenesis of COPD, a condition driven by inflammation (Chen et al. 2021; Lee et al. 2015). The gene discussed is ITIH4; the disease is chronic obstructive pulmonary disease.