The article outlines the relationships that obtain among schizophrenia, smoking, and smog. An overview of known scientific facts concerning the pathogenesis of schizophrenia is first provided. The relationship this has with nicotine addiction is discussed next, and finally the notion is introduced that heterocyclic amines found in cigarette smoke and petroleum fumes serve as a potent environmental neurotoxin that seriously compromises mental health in biologically susceptible individuals. It is argued that such biologic susceptibility takes the form of cerebral diabetes, which accounts for the serious impairment of glucose metabolism as demonstrated by positron emission tomography. Central to this argument is the view that diabetes can be peripheral, without affecting the central nervous system, or central, without affecting the peripheral system.