It turns out, breathing in polluted air doesn’t just negatively affect lung function. It may impair memory, too.
In a recent study, researchers from the University of Warwick in the UK found that people living in some of the most polluted districts of England have significantly poorer memory than people living in cleaner places.
Their findings also suggest that air pollution could age the brain by as much as 10 years. “When it comes to remembering a string of words, a 50-year-old in polluted Chelsea performs like a 60-year-old in Plymouth,” said co-author Andrew Oswald, who teaches economics and behavioral science at Warwick.
Their findings will be published in the journal Ecological Economics.
Exposure to air pollution ages the brain, affects memory
For their study, Oswald and his colleague, Nattavudh Powdthavee, randomly sampled 34,000 English citizens from across England’s local authority districts. Oswald and Powdthavee had the volunteers undergo a memory test, where they were told to remember 10 words.
The researchers adjusted for factors that could affect memory, including age, health, level of education, family, ethnicity and employment status. They also examined data on nitrogen dioxide (NO2), a pollutant produced by road traffic, and particulate matter (PM10) across 318 geographical locations. PM10 can be emitted from both natural sources, such as pollen and dust, and anthropogenic sources, such as factories and constructions.
The data showed that Kensington and Islington had the most polluted air, whereas West Somerset and Devon had the cleanest. When the researchers analyzed this data with the results of the memory test, they found that people living in parts of England with higher levels of NO2 and PM10 had poorer memory than people living in cleaner districts.
“We are still not exactly sure how nitrogen dioxide and air particulates act to do this,” said Oswald.
The study is one of the first to confirm the negative association between air pollution and memory. While still inconclusive, the researchers say that other scientists could use their findings when conducting more studies on the link between air pollution and memory.
Exposure to particulate matter linked to impaired memory in children
In another recent study, researchers found that early-life exposure to fine particulate matter (PM2.5) is linked to impaired memory and poor attention control in children.
Previous animal studies have shown that exposure to PM2.5 caused inflammation in the brain. But the effects of PM2.5 on human brains remain unclear.
To this end, the researchers recruited 2,221 children ages seven to 10 years from Barcelona, Spain. They had determined that, as a group, these children were exposed to an annual average of 16.8 micrograms of PM2.5 per cubic meter of air (ug/m3), which exceeds the recommended limit set by the World Health Organization (WHO) at 10 ug/m3.
Over the course of one year, the researchers tested the children’s memory and attentiveness during four visits. To correlate exposure to PM2.5 with cognitive development, they developed statistical models that monitored changes in the children’s average test scores associated with increases in PM2.5 concentrations.
The results of the memory test showed that lifetime exposures of PM2.5 at 10 ug/m3 was associated with a 16 percent drop in test scores. As a whole, the boys’ scores declined more sharply than the girls.
Meanwhile, exposure to PM2.5 concentrations higher than 10 ug/m3 was associated with slower responses in the test that assessed the children’s attention control. (Related: Children exposed to air pollution on their way to school have stunted cognitive development and memory problems, study finds.)
Overall, their findings show an inverse association between exposure to PM2.5, memory and attention control. But more importantly, these findings confirm that exposure to air pollution in early life may negatively impact neurodevelopment, explained researcher Xi Chen, an associate professor of public health at Yale University in Connecticut.
Chen speculated that exposure to PM2.5 could have also caused inflammation in the children’s brains. He and his colleagues now plan to examine how exposure to PM2.5 during pregnancy will affect brain development in fetuses and newborns.
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