Long-term exposure to air pollution leads to a massive reduction in intelligence, impacting simple math solving skills, a collaborative study by researchers from Yale and Peking universities claimed.
“Long-term exposure to air pollution impedes cognitive performance in verbal and math tests,” said one of the study's authors, Xiaobo Zhang, chair professor of economics at Peking University.
“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 added, “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.”
The study, titled “The impact of exposure to air pollution on cognitive performance,” co-authored by IFPRI’s Xiaobo Zhang, Xin Zhang of Beijing Normal University, and Xi Chen of Yale University, has been published in Proceedings of the National Academy of Sciences (PNAS) journal.
Researchers based their findings on a sample size of nearly 32,000 respondents. Surveyed respondents were examined on the basis of long-term and short-term exposure to air pollution from 2010 to 2014.
Both verbal and math scores decreased with increasing cumulative air pollution exposure, with a steeper decline for verbal scores than math scores, the study found. The decline in verbal scores was more pronounced among males than females.
Among males, the decline in verbal scores became more pronounced with age, and this age dependence was more significant in those with less than a middle school education compared with a middle school education or more.
“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. This finding has been neglected in the policy discourse, and has important policy implications,” said Zhang.
Researchers also found that a lower concentration of fine particulate matter helps in improving both verbal and problem-solving capabilities.
Reducing fine particulate matter concentrations to the US Environmental Protection Agency (EPA) standard (50 μg/m3) would increase verbal and math scores by 2.41 and 0.39 points, respectively, equivalent to an increase from the median to the 63rd and 58th percentiles, respectively, a press statement from ISRI maintained.
The study comes as a setback to developing countries that house the majority of world's worst polluted cities. A recent World Health Organization (WHO) study found that the world’s top 20 most polluted cities are in developing countries.
“Almost all the cities in low- and middle-income countries with more than 1,000,000 residents fail to meet WHO air quality guidelines,” researchers maintained. Among the world’s 10 most polluted cities, nine are in India.
Earlier studies had found irreversible damage to lungs leading to premature deaths and low productivity of workers.
The combined effects of outdoor and household air pollution, according to WHO, leads to about seven million premature deaths every year.
Most of these deaths are “as a result of increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections,” WHO study maintained.
By Alok Gupta
