The chapter explores the relationship between highly polluted environments and the development of dementia, focusing on Alzheimer's disease and the presence of PM2.5 particles in the brain. It emphasizes the importance of reducing exposure to harmful chemicals in the home for brain health. Additionally, it discusses the benefits of lifestyle factors like exercise and diet in preventing dementia, as well as potential medications like intranasal insulin and semaglutide in reducing the risk of Alzheimer's.