Air Pollution Exposure Harms Cognitive Performance, Study Finds

Smog in Beijing.   Kevin Frayer  Getty Images

While physical health has always been thought the most common casualty of air pollution, the study is the first to link poor air quality to cognition and an increase the risk of Alzheimer's disease, the most common form of dementia.

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. "Therefore, a narrow focus on the negative effect on health may underestimate the total cost of air pollution", Zhang said.

Results were the worst in South Asia, where air pollution shortens more lives than all types of cancer combined.

Carbon monoxide, ozone and larger particulates were not included in the study.

The study, published in the Proceedings of the National Academy of Sciences on Monday, added that pollution increases the risks of Alzheimer's disease and other forms of dementia.

Although the researchers were confident in linking pollution and cognitive decline, they are not sure why it is happening.

The study, conducted in China, showed a causality between inhaling excessive amounts of pollution and a significant drop in language and arithmetic, equivalent to a person losing a year in education. According to one recent study, from 2005 to 2016, about one-third of China experienced PM10 levels above 70 μg/m.

However, while establishing a link between pollution and lower test scores, the study did not prove cause and effect.

They found the longer people were exposed to dirty air, the bigger the damage to intelligence, with language ability more harmed than mathematical ability and men more harmed than women.

"This latest study matches with previous research", says Derrick Ho of Hong Kong Polytechnic who has worked on the health effects of extreme weather events like haze.

"Investment in cleaning up air pollution is not only good for health, but also for the intellect of society at large".

Xin Zhang, Xi Chen, and Xiaobo Zhang - the researchers - aim to fill a gap in knowledge where air pollution and its effects to human health is concerned.

According to the World Health Organization, which surveyed more than 4,300 cities worldwide, found that 80% of the populations surveyed lived in areas with unsafe levels of particulate matter and other pollutants. It is alarming that more than 8,500 children die every year in the country from diseases caused by indoor air pollution.

China came out as the most polluted country in a separate study by research group Eco Experts last month, with three cities in the top 10 - Beijing, Guangzhou and Shanghai.

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