You might want to cover your nose the next time you are going out the city. A study conducted by the researchers of Universities Lancaster, Oxford and Manchester found out that the air we breathe can potentially increase the risk of having Alzheimer's disease.

The conclusion was made after they have detected for the first time millions of magnetites from air pollution in human brain. While biologically produced magnetites have been suspected to exist in human brain for natural reasons, this is the first time they have seen traces that originated from the outside environment.

According to the study published in Proceedings of the National Academy of Sciences, the researchers examined the postmortem samples of brain tissues from 37 people who died with Alzheimer's disease. Using high-resolution imagery and spectroscopic analysis, the researchers found an alarming volume of magnetites on the brain tissues.

Unlike the usual biologically produced magnetites, most of the magnetites found on their brain tissues were spherical with diameters up to 150 nm. That's when they realized that the magnetites are similar to those from vehicular engines and open fires.

"The particles we found are strikingly similar to the magnetite nanospheres that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes," Professor Barbara Maher, from Lancaster Environment Centre, co-author of the study said in a press release.

"Our results indicate that magnetite nanoparticles in the atmosphere can enter the human brain, where they might pose a risk to human health, including conditions such as Alzheimer's disease," added Professor Maher," she added.

Magnetites, according to Science Mag, is essentially toxic in large volumes as they causes oxidative stress, disrupting normal cellular function and contributing to the creation of destructive free radicals.

Aside from magnetites, they also detected several traces of platinum, nickel, and cobalt which are very unnatural and potentially toxic.