APOE and Alzheimer disease: We discuss the APOE4 effects that influence AD pathogenesis and how exposures to fine particulate matter (PM2.5, particles ≤ 2.5 μm), ultrafine particles (UFP ≤ 100 nm) associated with fossil fuel combustion and friction processes, and industrial manufactured nanoparticles (NPs ≤ 100 nm) are major contributors to an ample variety of neural effects, including cerebrovascular dysfunction, neuroinflammation, oxidative stress, and extensive organelle pathology and dysfunction [30,31,32,33,34,35,36,37,38,39,40,41].