NLRP3 and depressive symptom measurement: In particular, Chu et al. (2019) identified the Nrf2/NLRP3 signaling pathway (which modulates inflammation) as key regulator of depression associated to PM2.5 exposure, reporting that depressive-like responses to PM2.5 were dose-dependent and could be partly explained by dysfunctions in neurotransmitter systems and the accumulation of toxic elements from polluted air, such as Be, Al, Cr, Co, Ni, Se, Cd, Ba, Ti, and Pb.