Exhaust fumes can disrupt brain connections in as little as two hours.

These findings are based on a study of 25 healthy adults who were exposed to vehicle pollution in a laboratory setting. In another step, participants were also exposed to clean, filtered air. Computer scans showed that after inhaling the fumes, connections between areas of the brain that are responsible for functions such as introspection and memory decreased. Scientists warn that chronic exposure to polluted air can be detrimental to the brain. This is especially dangerous since up to 99 percent of the world's people live in unclean environments.