n yet more bad news for those of us who have spent years sucking down China’s smog, a new survey has found that air pollution makes you less intelligent.
The survey — conducted by researchers from Yale and Peking University — tested more than 25,000 people living around China on standardized math and language questions. First in 2010 and then 2014.
Next, researchers compared the results of these with the relative levels of pollution (sulfur dioxide, nitrogen dioxide, and PM10) in test-takers’ localities. In the end, they discovered that air pollution has a “huge” negative effect on human intelligence with participants estimated to have lost an average of one year of education.
According to the study’s co-author Xi Chen, a professor of health policy and economics at the Yale School of Public Health, the effect is even more pronounced on the elderly, who may be losing several years of education in the toxic air.
Meanwhile, those most affected are old men without much education who are more likely to work outside and be exposed to higher levels of pollution. Differences between male and female brains may also account for this difference, the study said.
However, as scary as this all may sound, correlation does not imply causation. Some skeptics believe that this survey does not do enough to establish cause and effect, noting that numerous other factors may be at work here. Chen claims that by testing the same people four years apart, the study was able to account for other factors.
Though, if air pollution does indeed cause a reduction in intelligence, the study still was not able to explain how this happened, apart from some strands of speculation about the pollution harming the brain’s white matter.
Past surveys have also linked China’s smog to millions of early deaths as well as weight gain. However, thanks to a massive government clean-up campaign, the skies are looking a bit brighter in the Middle Kingdom in recent years. This July, Beijing residents enjoyed the bluest skies they had seen in a decade.