A new study from Lancaster University has discovered toxic nanoparticles from air pollution in large quantities in human brains. The researchers examined brain tissue from 37 people aged between 3 and 92 years old in the U.K. and Mexico. Magnetite, a type of iron oxide, was found in massive quantities in the samples – millions of particles per gram of brain tissue.

Finding any particles connected to air pollution in the human brain would be troubling, but magnetite is particularly concerning. Recent research has found that these particles may be linked to Alzheimer’s disease, and exposure air pollution has been shown to significantly increase the risk of developing the illness. While there’s been no definitive proof yet that these particles cause the disease, the link is enough to make health researchers wary.

While magnetite is known to form naturally in brain tissue, the biological variety is small and crystal-shaped. The particles associated with air pollution and suspected to be harmful are large and spherical, formed as molten droplets from combustion sources such as industrial processes or car exhaust. The study found about 100 times the pollution-linked particles as it did the naturally-occurring ones. This ratio makes sense when you consider that roadside air analysis in Lancaster, England found as many as 200 million of these particles per cubic meter.

The study also found other metal particles in the brain that are suspected to come from car exhaust, including platinum, cobalt and nickel. It’s believed that these particles are able to build up due to the unique way the body processes inhaled substances. When air pollution enters the nose, it’s able to completely bypass the blood-brain barrier and directly enter the brain through the nose.

Read more: http://www.enn.com/pollution/article/49982