Air pollution may be making us stupider

Air pollution not only makes you sicker, it might make you stupider, too.

A new study published in the journal Proceedings of the National Academy of Sciences found that exposure to high levels of air pollution leads to significant drops in test scores in language and math.

Researchers Xin Zhang, Xi Chen, and Xiaobo Zhang conducted their study in China, which has notoriously bad air pollution, analyzing language and math test scores of 20,000 people across the nation between 2010 and 2014. The scientists compared the test results with records of nitrogen dioxide and sulphur dioxide pollution and found what they believe is direct causation between air pollution and falling test scores.

“Polluted air can cause everyone to reduce their level of education by one year, which is huge,” Xi Chen, one of the researchers at the Yale School of Public Health, told the Guardian. “But we know the effect is worse for the elderly, especially those over 64, and for men, and for those with low education. If we calculate [the loss] for those, it may be a few years of education.”

Air pollution not only has a long-term impact on intelligence, but a short-term impact as well, which could spell bad news for students trying to take exams when the air is particularly polluted. The researchers note that the stupidification of the population can lead to “substantial health and economic costs.”

By some estimates, 95% of the world breathes unsafe air, making it the greatest environmental health risk on the planet. Air pollution is the fourth highest cause of death around the world, coming in just after high blood pressure, diet, and smoking.

The solution to the problem seems clear—clean up the air, or hold your breath forever.