air pollution directly affects cognition

Air pollution and impaired lung function prove independent risk factors for cognitive decline

(...) "Our findings disprove the hypothesis that air pollution first decreases lung function and this decline, in turn, causes cognitive impairment by releasing stress signals and humoral mediators into the body," explains Mohammad Vossoughi, a PhD student at the Leibniz (Germany) Institute for Environmental Medicine, who led the study.

Mr. Vossoughi adds that the findings suggest other hypotheses about how air pollution affects cognition, including the possibility that particulate matter and other pollutants are translocated to the central nervous system via our sense of smell and that leads to mild cognitive impairment. (...)

http://www.sciencedaily.com/releases/2015/05/150518121147.htm