Reuters

A growing body of evidence connects urban pollution with harmful brain alterations

For all the benefits of growing up urban, there are some considerable health risks too. In an upcoming issue of the journal Brain and Cognition, an international team of researchers reports that exposure to urban air pollutants "may perturb the trajectory of cerebral development and result in cognitive deficits during childhood." Simply put, the kids in cities may not be all right.

The researchers, led by Lilian Calderón-Garcidueñas of the National Institute of Paediatrics, in Mexico City, and the University of Montana, studied a group of 30 children aged 7 or 8 who had lived in Mexican cities their whole lives. Some came from Mexico City, a place known for its extremely high levels of air pollutants, while others lived in Polotitlán, a city with a strong air quality rating.

The researchers tracked the children for two years, using an array of tools — including brain scans — to measure volume of white matter, neuroinflammation, and cognitive performance in the youths. They found that the brains of kids from cleaner Polotitlán looked healthier than those of Mexico City children, and performed better too. On tests of complex reasoning, knowledge integration, and verbal and working memory skills, the Mexico City kids scored lower than did the other children. The researchers conclude:

Children who appeared to be healthy and had no risk factors for neurological or cognitive deficits, but who are residents in a highly polluted atmosphere, exhibited selective impairment in IQ subscales tapping on attention, short term memory and learning abilities. ...

If cognitive abilities are reduced during the critical childhood developmental years as a result of air pollution, it will have enormous detrimental effects on society.

While scientists have a good sense of how city smog harms the lungs and the heart, its impact on brain functioning has been poorly understood until late. The recent work of Calderón-Garcidueñas and others in her field is starting to inform this knowledge gap. In a study from 2008, Calderón-Garcidueñas and colleagues found that 56 percent of otherwise healthy Mexico City kids had lesions of the prefrontal cortex, compared with less than 8 percent of youths from a low-polluted region. At a recent professional meeting, covered by science reporter Janet Raloff, Calderón-Garcidueñas noted a troubling similarity between the types of brain abnormalities she's finding and the hallmarks of Alzheimer's disease.

The problem isn't unique to Mexico City. In other work from 2008, Harvard researchers studied about 200 children from Boston and found a connection between black carbon — the type of soot kicked up by heavy city traffic — and decreased performance "across assessments of verbal and nonverbal intelligence and memory constructs." A 2009 study out of Brescia, Italy, noticed a link between airborne manganese particles and impaired motor coordination and olfactory functions.

About the Author

Most Popular

  1. photo: San Diego's Trolley
    Transportation

    Out of Darkness, Light Rail!

    In an era of austere federal funding for urban public transportation, light rail seemed to make sense. Did the little trains of the 1980s pull their own weight?

  2. Design

    What’s Behind the Iconic Floor Plan of London

    The most common residential floor plans in European cities offer a window into urban history and culture. In London, it’s the “two-up, two-down” row house.

  3. photo: NYC subway
    Transportation

    Behind the Gains in U.S. Public Transit Ridership

    Public transportation systems in the United States gained passengers over the second and third quarters of 2019. But the boost came from two large cities.

  4. Equity

    What ‘Livability’ Looks Like for Black Women

    Livability indexes can obscure the experiences of non-white people. CityLab analyzed the outcomes just for black women, for a different kind of ranking.

  5. photo: Developer James Rouse visiting Harborplace in Baltimore's Inner Harbor.
    Life

    What Happened to Baltimore’s Harborplace?

    The pioneering festival marketplace was among the most trendsetting urban attractions of the last 40 years. Now it’s looking for a new place in a changed city.

×