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Barcelona, Spain – A groundbreaking study led by the Barcelona Institute for Global Health (ISGlobal) has unveiled alarming evidence that air pollution significantly impacts brain development in children. The research, which examined over 4,000 children in Rotterdam, the Netherlands, reveals that exposure to harmful pollutants, particularly fine particulate matter (PM2.5) and nitrogen oxides (NOx), during pregnancy and childhood is linked to alterations in the microstructure of the brain’s white matter. Notably, some of these detrimental effects persist into adolescence.
White matter is a crucial brain structure responsible for facilitating communication between different regions of the brain. As concerns grow over the effects of air pollution on neurodevelopment, this study underscores the urgent need for public health initiatives targeting air quality, especially for pregnant women and young children.
Air Pollution and Neurodevelopment
Previous research has established a correlation between air pollution and negative outcomes in neurodevelopment. However, earlier studies were often limited in scope, relying on single-time-point assessments and failing to track participants over time. “Following participants throughout childhood and including two neuroimaging assessments for each child would shed new light on whether the effects of air pollution on white matter persist, attenuate, or worsen,” stated senior author Mònica Guxens.
The current study aimed to fill this gap by closely monitoring children from birth as part of the Generation R Study.
Study Findings: Childhood Exposure to Pollutants
Researchers estimated the children’s exposure to 14 different air pollutants based on their residential locations during pregnancy and childhood. For 1,314 children, the team conducted two brain scans—one around age 10 and another at age 14—to evaluate changes in white matter microstructure.
The findings revealed that higher exposure to PM2.5 during pregnancy and childhood corresponded with significant changes in white matter development. Specifically, increased exposure to PM2.5 and NOx was associated with lower levels of fractional anisotropy (FA), a measure indicating how water molecules diffuse within the brain. This correlation suggests that more developed brains exhibit higher FA values due to more directional water flow.
Crucially, the effects of air pollution on brain development persisted into adolescence, with increased pollution exposure leading to developmental delays in FA equivalent to over five months.
Mechanisms Behind the Impact
Lead author Michelle Kusters highlighted that the observed lower FA levels likely result from changes in myelin—the protective sheath surrounding nerves—rather than alterations in nerve fiber structure. Although the precise mechanism remains unclear, it is hypothesized that small particles may penetrate the brain or that inflammatory responses triggered by inhaled particles could lead to neuroinflammation and neuronal death, as evidenced in animal studies.
The researchers also noted that some pollutants affected another white matter measure, mean diffusivity (MD), which typically decreases as the brain matures. Higher prenatal exposure to silicon in PM2.5 was linked to initially elevated MD, which then declined more rapidly as the children aged, suggesting that the impacts of air pollution may diminish over time.
Policy Implications: Stricter Pollution Guidelines Needed
Alarmingly, the study found that these adverse effects occurred at PM2.5 and PM10 levels exceeding the World Health Organization’s recommended limits but still below those permitted by the European Union. Guxens emphasized the need for stricter European air pollution guidelines, which are anticipated to be approved soon by the European Parliament.
“Our study provides support for the need for more stringent European guidelines on air pollution,” Guxens added, underscoring the importance of regulatory measures to protect vulnerable populations.
Lasting Changes in White Matter Development
Previous research by Guxens and her team also demonstrated that early exposure to environmental factors like heat and cold could influence white matter microstructure, particularly among children in lower-income neighborhoods. The current study reinforces the link between air pollution exposure during critical developmental periods and lasting changes in brain structure.
As the research reveals, each increase in air pollution exposure correlates with more than a five-month delay in the development of fractional anisotropy.
The findings, published in the journal Environmental Research, call for urgent action to mitigate air pollution and safeguard the health and development of future generations.
