Also, some of these particles enter the brain directly through the olfactory nerve. http://www.pnas.org/content/113/39/10797.abstract http://www.pnas.org/conte

Also, some of these particles enter the brain directly through the olfactory nerve. http://www.pnas.org/content/113/39/10797.abstract http://www.pnas.org/content/113/39/10797.abstract easier to read: https://www.theguardian.com/environment/2016/sep/05/toxic-air-pollution-particles-found-in-human-brains-links-alzheimers https://www.theguardian.com/environment/2016/sep/05/toxic-ai...