APP and Alzheimer disease: Research suggests that exposure to PM2.5, a type of air pollution particle, may induce DNA methylation changes reminiscent of those found in Alzheimer’s disease, including BACE1, APP, PS1, and APOE. Some studies have demonstrated that PM2.5 can influence Aβ generation by altering BACE1 methylation, leading to a cascade of pathological events [192].