Earlier this week a colleague of mine who is a professor at Cal Poly Pomona in southern California posited an interesting question that I had never really thought of: Should you always drive into LA with your windows rolled up? He's a researcher in carcinogens and immunological responses to the development of cancers so immediately I assumed that his question must have met a sort of cancerous end, but it appears that he's not the only one thinking about the pollution problem. According to a new study published this week in the journal Stroke, researchers found the first link directly correlating changes in brain volume to exposure to air pollution, and during the 10-year monitoring period found that brains exposed to areas of dense air pollution were smaller leading to poorer cognitive function-poorer thinking and memory problems just being the start.

According to the team Harvard University, led by lead author Elissa H. Wilker, not only did brains shrink by 0.32 percent, which may seem nominal but has devastating effects, but with the exposure to pollution so too came a 48 percent increase in the risk of a silent stroke.

"Long-term exposure to air pollution showed harmful effects on the brain in this study, even at low levels, particularly with older people and even those who are relatively healthy" Wilker says. "We found that people who live in areas where there are higher levels of air pollution had smaller total cerebral brain volume and were more likely to have evidence of covert brain infarcts."

But what does this all mean? How bad exactly are air pollutants for your brain? Aside from being bad for your skin, allowing free-radicals to age you beyond your years, it appears that air pollution may too age your brain-and it's nothing to make you any the wiser. Causing major alterations in your cognitive ability and your ability to recall long-term memories, Wilker says that the change in brain volume actually will age your brain one year more than average.

"The magnitude of association that we observed for brain volume was similar to approximately one year of brain aging."

Want to Know Your Risk?

Well the bad news is that according to the American Lung Cancer Association, nearly 60 percent of all Americans live in areas of air pollution, which the EPA has associated with respiratory problem, neurodegenerative diseases and many other serious health risks. But if you want to know exactly how your city fares, you can check out StateoftheAir.org to find out your risk.