Air pollution is making us dumber, study says

(CNN) - Air pollution may do more than affect people's lungs. It may also negatively impact their brain.

A study in the Proceedings of the National Academy of Sciences said breathing polluted air results in a "steep reduction in verbal and math test scores."

The data is based on roughly 32,000 people over a four-year period in China.

Researchers said older men seemed to be especially susceptible to a drop in cognitive abilities.

According to the study, cognitive problems can lead to other health problems, including dementia.

The World Health Organization said nine out of every 10 people on the planet breathe air containing a high level of pollutants, Africa and Asia being the worst affected regions.

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