These fine particulate particles get directly into the brain via the nose. Once in the brain, they elicit an inflammatory response causing neuroinflammation. The adverse effects were stronger in women who had the APOE4 gene, a genetic variation that increases the risk for Alzheimer’s. Air collected over the 10 Freeway in Los Angeles led to 60% more brain amyloid plaque in mice. Another study found that for every 3.5 micrograms of PM2.5 per cubic meter of air, white matter (the myelinated region of the brain) decreased by 6 cubic centimeters. Air pollution has been declining steadily since the EPA promulgated new standards in 2012 and it is important to keep these regulations of air pollution in place.