This Week In Wellness breathing in clean air has been shown to reduce the risk of Alzheimer’s and other dementias.

Tint particulate matter released by cars and factories known as PM2.5 has previously been linked to memory loss and Alzheimer’s disease due to the capacity of the tiny particles to pass directly up into the brain (via the nose) and hence bypass the blood-brain barrier. It has also been been linked to premature death, particularly in people with chronic heart or lung diseases.

https://www.sciencedaily.com/releases/2021/10/211007122123.htm