New research from McGill University in Canada has linked airborne nanoparticles produced by motor traffic to brain cancer for the first time ever. The ultra-fine particles produced by diesel vehicles significantly increase people's chances of getting the deadly disease.

The findings, published in the journal Epidemiology, pointed out that a one-year increase in pollution exposure increased the risk of brain cancer by more than 10 percent. Past works have shown that nanoparticles can reach into the brain and that they can carry carcinogenic chemicals.

The study saw that a one-year increase in pollution exposure to 10,000 nanoparticles per cubic centimeter. The researchers considered in the study several factors, including but not limited to income, smoking, and obesity, and whether or not people moved houses.

Brain cancers are rare, and the scientists have anticipated that an increase in pollution exposure, equivalent to moving from a quiet city street to a busy one, leads to a new case of brain cancer for every 100,000 people exposed.

Scott Weichenthal, a researcher who led the study, said environmental risks such as air pollution are not substantial in magnitude; however, its importance comes because everyone in the population is exposed to such pollution. 

 "There can be lots of circumstances by when you multiply these small cases; it [the proofs] could be significant in number, especially given the fact that the tumors are often fatal," he explained.

The researchers examined the medical records and pollution exposure of 1.9 million Canadian grown-ups from 1991 to 2016. Such extensive research provides strong evidence.

The association between brain cancer and nanoparticles, according to Weichenthal, was "surprisingly consistent."

The discovery of toxic nanoparticles from air pollution in human brains was made in 2016. A comprehensive global review earlier this year concluded that air pollution might damage every organ and every cell in the human body.

Toxic air has been linked to other effects on the brain, including considerable reductions in intellect, and would cause dementia and mental health problems in both children and grown-ups. Air pollution, according to the World Health Organization, is a "silent public health emergency."

"We don't know a lot about the causes of brain tumors, so any environmental factors we can identify help [point out the causes]," Weichenthal said. The researchers only relied on air pollution data for their study and assumed the differences between different streets and districts were the same in the past. "We think this would be enough since major highways don't move around," Weichenthal explained.

Barcelona Institute for Global Health Professor Jordi Sunyer, who was not involved in the new research, welcomed the results as ultrafine particles are directly emitted by cars. He also noted several studies in animals have shown UFPs could be more toxic than larger particles.

Weichenthal said he avoids "heavily polluted streets" when exercising outdoors. He said reducing one's exposure to pollutants is always a good idea. "But the more important actions are in moderate where you can act which lessens everyone's exposure [to pollution]. That is where the real benefits come in."