Air pollution is a growing global health concern estimated to contribute to as many as 4.2 million premature deaths worldwide per year. So it poses the greatest environmental risk to human health. A strong and rapidly expanding body of evidence links ambient air pollution to respiratory and cardiovascular conditions that eventually may also affect cognition in the elderly. Among various ambient air pollutants, particulate matter (PM) has been implicated as a chronic source of neuroinflammation and reactive oxygen species that produce neuropathology resulting in neurodevelopmental disorders and neurodegenerative disease. The current review will briefly discuss the clinical features and underlying mechanism of PM induced cognitive dysfunction, more specifically, dementia.