Research indicates long-term exposure to air pollution may cause the brain to shrink and lead to dementia or stroke. The research dealt with fine particle air pollution -- less than 2.5 micrometers in diameter -- which comes from burning wood or coal, car exhaust and other sources.
"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," lead author Elissa H. Wilker, a researcher in the Cardiovascular Epidemiology Research Unit at Beth Israel Deaconess Medical Center and the Harvard T.H. Chan School of Public Health in Boston, said in a press release.
"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."
The decadelong study, which began in 1995, involved 943 adults in New England and New York. The researchers used magnetic resonance imaging to analyze the effect of long-term air pollution on brain structure and found small particulate pollution was associated with a 0.32 percent decrease in brain volume -- equal to one year of aging -- and a 46 percent higher risk of neurological abnormalities, poorer cognitive function and dementia.
The World Health Organization has noted fine particulate matter affects more people than any other pollutant, and chronic exposure can lead to serious disease and death. The pollutants can contribute to narrowing of the arteries that supply blood to the brain. WHO estimates air pollution caused 3.7 million premature deaths worldwide in 2012, with 88 percent occurring in low- and middle-income countries, mostly in the western Pacific and Southeast Asia.
The research was published in the American Heart Association journal Stroke earlier this week.