Humans have long been exposed to three main types of smoke: from early domestic fires, modern wildfires, and more recently, tobacco and fossil fuel pollution. All release tiny particles from partly burned plants, containing harmful chemicals like nitrogen oxides and carcinogens. These particles raise risks for lung cancer, dementia, and even childhood obesity. Studies show that air pollution can disrupt brain chemistry, increase Alzheimer's-related proteins, and activate stress-related genes (NFkB, Nrf2). A new drug (GSM-15606) shows promise in reducing brain damage from pollution in mice. People with the ApoE4 gene may be more vulnerable, while the ApoE3 gene, possibly evolved 200,000 years ago, may offer some protection. (#40700)