'Level of air pollution in cities may impair brain'

Waiting at a traffic signal behind a vehicle spewing pollutants could hurt your ability to learn.

Waiting at a traffic signal behind a vehicle spewing pollutants could hurt your ability to learn.

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Exposure to particulate matter (PM) pollution over prolonged periods at levels typical of Delhi and other Indian and Chinese cities could impair cognition, cause depression and chronically damage key parts of the brain, scientists have found.

The findings, published in the Nature Journal Molecular Psychiatry, suggest that air pollution —known to cause body inflammation, high blood pressure, diabetes and obesity — has other previously ignored public health implications.

Most big cities in India actually have pollution levels higher than the ones we used in experiments by the researchers, Sanjay Rajagopalan, Ohio State University professor and a coauthor of the research said.

"We didn't expect the kind dramatic results we got. But the results suggest that it is very important for policy-makers in India to address these problems though it won't be easy," Rajagopalan told HT.

The researchers —Rajagopalan, Laura Fonken and Qinghua Sun — exposed one set of mice to polluted air and another set to filtered air for 10 months before performing a series of behavioral tests on them. Mice were tested because humans are exposed to several other influencing factors and isolating the impact of air pollution on the brain is difficult.

Delhi typically has average PM concentration of the range of 50-120 micrograms in every cubic metre, even after the reduced air pollution following the introduction of compressed natural gas (CNG). The mice were exposed to PM concentration of 80-90 micrograms per cubic metre. But the region directly behind a pollution spewing vehicle would typically have PM concentration as high as 600 micrograms per cubic metre. "The tests were specifically designed for conditions in Indian and Chinese cities," Rajagopalan said.