Exposure to air pollution could affect cognitive development, says new study

Chronic exposure to air pollution could impact cognitive abilities, reflected in decreased verbal and mathematics scores, apart from causing heart disease and breathing problems, suggests a new long-term study conducted in China.

The study, done by Chinese scientists at Peking University in Beijing and Yale University in the US and published in the journal Proceedings of the National Academy of Sciences, argued that “polluted air may impede cognitive ability as people become older, especially for less educated men”.

LONGTERM EXPOSURE IMPEDES COGNITIVE PERFORMANCE IN VERBAL AND MATH TESTS, WITH EFFECTS MORE PROMINENT DURING OLD AGE, THE AUTHORS SAID

Xiaobo Zhang, one of the authors of the study, said a narrow focus on the negative effects on health could underestimate the total cost of air pollution. “Our findings imply that the indirect effect of pollution on social welfare could be much larger than previously thought,” he said.

The study analysed language and arithmetic tests on 20,000 people across China between 2010 and 2014, comparing the results to varying levels of the pollutants nitrogen dioxide and sulphur dioxide. The impact of some other major pollutants such as carbon monoxide, ozone and larger particulates were not included in the study.

The researchers were able to show the scores in cognitive tests fell with increased longterm and transient exposure to air pollution. The decline was more pronounced in verbal tests than in mathematics.

The study’s findings could be relevant for India, which now has 14 of the world’s most polluted cities, including Kanpur and New Delhi.

“The findings should be applicable to India. In fact, the impact probably is greater given that the air pollution is more severe in Delhi than in Beijing and other Chinese cities,” said Zhang.

Doctors from India said the study is a good start but more research is needed to show the impact of air pollution on the human brain is definitive.

“The study points a way. However, the researchers have retrospectively analysed the data and tried to fit it into a mathematical model.

“This can just show a correlation between high pollution levels and lower scores,” said Vinay Goyal, professor of neurology at the All India Institute of Medical Sciences.