Recent research suggests that as you walk down the street, pump your gas, or ride in your car, iron particles may be traveling up your nose and into your brain through nerve endings. Prior to these findings, iron was thought to be present in the brain due to natural sources such as food; however, scientists are now saying that most of the iron found in the brain is in the form of magnetite particles (or iron dioxide) which comes from air pollution from automotive fumes and coal burning. These iron particles are highly magnetic and have been linked to Alzheimer's disease.
According to Barbara Maher of Lancaster University in the UK, "there is iron as impurities in fuel, and there is iron in a car engine block. If you walk down the street you'll be breathing them in-how could they not get into your system?"
The iron nanoparticles are less than 200 nanometers in diameter and are proposed to travel through nerve endings in the nose and up to the brain. Jo Anne Shatkin of Vireo Advisors, llc was quoted in New Scientist "it's not that surprising because we have known for a long time we get exposed to these nanoparticles. We are just getting a better ability to look at them."
Populations studies have shown that people who live in busier traffic areas have a higher risk of Mental impairment as they age. Shatkin suggests that steps to reduce air pollution may decrease our risk of Alzheimer's disease. While we have known there are nanoparticles occurring in our environment due to human and natural processes, this report links them to human exposure directly.