Researchers from China and the US have found that long-term exposure to air pollution impedes cognitive performance in verbal and math tests. In a study published in Proceedings of the National Academy of Sciences (PNAS), they report that the effect of air pollution on verbal tests becomes more pronounced as people age, especially for men and the less educated.

They suggest that the damage on the aging brain by air pollution likely imposes substantial health and economic costs, considering that cognitive functioning is critical for the elderly for both running daily errands and making high-stake decisions.

To perform the study, the researchers matched a nationally representative longitudinal survey and air quality data in China according to the exact time and geographic locations of the cognitive tests.

Air quality was measured using the air pollution index (API), which is calculated based on daily readings of sulfur dioxide (SO₂), nitrogen dioxide (NO₂ ), and particulate matter smaller than 10 μm (PM₁₀).

The API ranges from 0 to 500, with larger values indicating worse air quality. Daily API observations were obtained from the city-level air quality report published by the Chinese Ministry of Environmental Protection. The report includes 86 major cities in 2000 and covers most of the cities in China in 2014.

Our findings about the damaging effect of air pollution on cognition, particularly on the aging brain, imply that the indirect effect on social welfare could be much larger than previously thought. A narrow focus on the negative effect on health may underestimate the total cost of air pollution.

—Zhang et al.

Resources

• Xin Zhang, Xi Chen, Xiaobo Zhang (2018) “The impact of exposure to air pollution on cognitive performance” Proceedings of the National Academy of Sciences doi: 10.1073/pnas.1809474115