Chu et al. suggest that sub-chronic PM2.5 inhalation in mice could activate the Nrf2 pathway leading to enhanced antioxidative stress and the Nrf2 deficiency could strengthen the oxidative stress and activate nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome, which may contribute to depression-like behavior induced by PM2.5 [59]. This evidence concerns the gene NFE2L2 and depressive symptom measurement.