Air pollution is one of the most important environmental problems that our planet faces but it appears that poor air quality poses a bigger threat to its residents than previously thought.

According to an extensive study conducted by the Population Health Research Institute at St. George's University of London, those living in areas with poor air quality are at higher risk of dementia compared to those living in areas with better air quality.

The research studies a total of 131,000 people between the ages 50 and 79 for over the course of seven years and it turns out that air pollution increases the risk of dementia in that age group by 40 percent. At the end of the study, some 2,200 of the participants were diagnosed with dementia.

A previous study conducted in China also proved that air pollution caused underdeveloped intelligence.

Dementia is the seventh leading cause of death in the world, according to the World Health Organization (WHO). The syndrome involves the loss of cognitive functioning and behavioral abilities, and Alzheimer's disease is the most common cause of dementia in older adults.