It started with dogs: a neuroscientist noticed that aging dogs in polluted areas of Mexico City often grew confused, disoriented, and forgetful. Since then, evidence has grown that breathing polluted air may be bad for the brain—perhaps even increasing the risk of dementia in humans. For example, a recent study from the University of Toronto found that people in Ontario who lived within 50 meters of a major road were 12% more likely to get dementia than those who lived 200 or more meters away. There is more research to be done to figure out exactly what’s going on and if there are any safe levels of polluted air.
More details here at the Sciencemag.org –