Air pollution is making us dumber, study shows

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CNN News by James Griffiths

(Study author Xiaobo Zhang is a professor of Peking University, a senior research staff of IFPRI and an external affiliated faculty of CICER)

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Air pollution could be more damaging to our health than previously thought, according to a new study, which found that prolonged exposure to dirty air has a significant impact on our cognitive abilities, especially in older men.

According to the study published Tuesday in the Proceedings of the National Academy of Sciences, breathing polluted air causes a "steep reduction" in scores on verbal and math tests.

Researchers at the International Food Policy Research Institute (IFPRI) examined data from the national China Family Panel Studies longitudinal survey, mapping the cognitive test scores of nearly 32,000 people over the age of 10 between 2010 and 2014 against their exposure to short- and long-term air pollution.

The team found that both verbal and math scores "decreased with increasing cumulative air pollution exposure," with the decline in verbal scores being particularly pronounced among older, less educated men.

    "The damage air pollution has on aging brains likely imposes substantial health and economic cost, considering that cognitive functioning is critical for the elderly to both running daily errands and making high-stakes economic decisions," study author Xiaobo Zhang of Peking University said.

    Cognitive decline or impairment, which could be caused by air pollution according to the study, are also potential risk factors in developing Alzheimer's disease or other forms of dementia.

    Pollution exposure was measured using data on air quality, which includes three air pollutants: sulfur dioxide, nitrogen dioxide and particulate matter smaller than 10 micrometers in diameter.

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    Poor hardest hit

    While the study adds to the already numerous health concerns regarding air pollution, it will be of particular concern to developing nations, whose smoggy cities could be hampering national economic development.

    "The damage on cognitive ability by air pollution also likely impedes the development of human capital. Therefore, a narrow focus on the negative effect on health may underestimate the total cost of air pollution," Zhang said. "Our findings on the damaging effect of air pollution on cognition imply that the indirect effect of pollution on social welfare could be much larger than previously thought."

    According to the World Health Organization (WHO), nine out of every 10 people on the planet breathe air containing a high level of pollutants, with the worst affected regions being Africa and Asia.

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    Of the world's top 20 most polluted cities, as measured by the WHO, all are in developing countries. Almost all cities in low to middle-income countries with more than a million residents fail to meet minimum WHO guidelines.

    City dwellers aren't the only ones breathing in smog either, a study in January found that 75% of deaths related to air pollution in India were in rural areas.

    While some countries, including China, are taking measures to address air pollution, this will also potentially effect economic growth.

    Meanwhile, the wealthiest city dwellers are able to buy their way out of smog.

    In Beijing, the rich are specially designing their homes and buying appliances to filter out pollutants in their air and water, while poorer residents are stuck breathing in the unfiltered smog, affecting not only their health but also, according to the new study, their cognitive abilities.