We investigate how Chiang Mai haze-derived PM2.5 impacts oxidative stress and gene expression in three non-small-cell lung cancer (NSCLC) cell lines: A549 (<i>KRAS</i>-mutant), NCI-H1975 (<i>EGFR</i>-mutant), and NCI-H460 (<i>KRAS/PIK3CA</i>-mutant). Here, KRAS is linked to non-small cell lung carcinoma.