It turns out pollution affects more than just the environment. New research shows there might be a correlation between significant air pollution and cognitive decline in humans. Scientists hope their research will lead to changes in how countries deal with excessive air pollution, especially in heavily populated urban areas.

Over the course of several years, more than 25,000 people hailing from 162 different counties in China were studied. The researchers published their findings in the Proceedings of the National Academy of Sciences and are calling for China to reform its pollution policies. The researchers believe China can significantly increase the population’s education level by adhering to the U.S. EPA guidelines.

So, how did researchers link pollution with cognitive decline? The scientists performed verbal and math exams on all of the subjects in 2010 and again in 2014. The data from the exams were then compared between the years, and the team linked these changes to air pollution.

Woman looking to sky and wearing white mask over nose and mouth

The researchers found that the older subjects performed worse on the tests, which led the team to believe that pollution has a bigger effect on brains as people age. The study also showed that individuals with little education were more affected by pollution, possibly because they typically work outdoors.

Although the researchers were confident in linking pollution and cognitive decline, they are not sure why it is happening. Xi Chen, study co-author and professor of health policy at Yale, believes that pollution could be harming white matter in the brain, a region that controls communication within this important organ.

James Hendrix, the head of the Alzheimer’s Association’s Global Science Initiative, disagrees. Hendrix does not believe the researchers have any evidence to suggest that pollution is damaging white matter. He also argues that associating air pollution with cognitive deterioration is difficult, because there are too many other factors at play.

Either way, it’s clear that air pollution is negatively impacting our health and our planet.

+ Proceedings of the National Academy of Sciences

Via NPR

Images via Fredrik Rubensson and Nicolò Lazzati