Higher air pollution levels are linked to lower math and verbal test scores, according to a study of more than 25,000 people living throughout China. The analysis, which appeared yesterday (August 27) in PNAS, correlated test scores collected in a longitudinal study with official air pollution data to see how poor air quality was related to the same subjects’ performance over time.
The research team, led by Xiaobo Zhang of Peking University, found that exposure to increased levels of sulfur dioxide, nitrogen dioxide, and particulates smaller than 10 μm (PM10) were tied to lower verbal test scores (math scores to a lesser extent, and only when people were exposed for weeks or more). Exposure over longer periods of time correlated with larger drops in performance, and the effects were most pronounced for men and older people.
Coauthor Xi Chen tells NPR that if China were to reduce levels of PM10 to less than 50 μg/m3, the cognitive gains would be equivalent to that of an extra year of education for the entire population. According to one recent study, from 2005 to 2016, about one-third of China experienced PM10 levels above 70 μg/m3.
“The damage on cognitive ability likely impedes the development of human capital,” coauthor Xin Zhang of Beijing Normal University tells Buzzfeed. “It is so widespread that [it] can impose substantial costs to everyone’s daily life and critical decision-making.”