The Washington PostDemocracy Dies in Darkness

Young kids who breathe polluted air can fall behind in school, study finds

Cars and trucks move along the Cross Bronx Expressway, a notorious stretch of highway in New York that contributes to pollution and poor air quality. (Spencer Platt/Getty Images)
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Young children living in neighborhoods with high rates of poverty are more likely to be exposed to many different air pollutants, and that can harm their development during early childhood, according to a study published Wednesday. The children’s increased exposure to air toxins during infancy can reduce reading and math abilities and cause them to fall behind — for some, the effect is equivalent to losing an entire month of elementary school.

While there are other issues that can affect school preparedness for early-age children, the study found that exposure to air pollutants, when isolated, accounted for a third of the impact when compared with other concerns.

It has long been known that poorer communities are disproportionately exposed to air pollution than more-affluent communities, but the study, published in Science Advances, dives deeper into some impacts, exploring the intersections of neighborhoods’ socioeconomic status and the effects on early-childhood cognitive development, while looking at disparities in air quality.

In the study, researchers show the ways cognitive gaps are formed as early as 6 months and are entrenched by age 2, before children even start school, said lead researcher Geoffrey Wodtke, associate director of the University of Chicago’s Stone Center for Research on Wealth Inequality and Mobility.

“The study is showing that children born into high-poverty neighborhoods are more likely to be exposed to many neurotoxic air pollutants, and that those differences in turn are linked with inequalities in early-childhood development, specifically reading and math abilities measured around the time of school entry,” Wodtke told The Washington Post.

Researchers used data from the U.S. Department of Education’s early-childhood longitudinal study birth cohorts, which assessed 10,000 children born in or around 2001, tracking them through the time they entered kindergarten. The children were from across the United States.

Researchers analyzed the socioeconomic status and air pollution concentrations of the children’s neighborhoods. Scientists then followed the children until they were about 4 years old, when they were assessed for early reading and math skills.

“What’s important is we provide some initial and relatively strong evidence that being born into a poor neighborhood harms early cognitive development, and this is at least partly due to exposure to neurotoxic air pollution,” Wodtke said in a statement.

Some pediatric environmental health scientists were not surprised by these findings, pointing to previous literature and research on early exposure to air pollutants and the relationship with lower cognitive test scores. But the study provides a steppingstone to understanding how air pollution affects other factors that may influence children’s healthy neurodevelopment, said one pediatrician and professor who has studied intersections.

“This is really important because we have significant health inequities of all kinds for children in the U.S. that tracks with poverty,” said Catherine Karr, an environmental epidemiologist and pediatric environmental medicine specialist at the University of Washington.

“Clean air is part of the prescription for every child to meet their full health potential, including cognitive health,” added Karr, who was not involved in the study.

In the study, scientists differentiate between the types of exposures. Poorer communities were more exposed to particulate matter and traffic-related pollution like nitrogen dioxide and carbon monoxide — exposures that appeared to have more of an impact on reading and math abilities during early-childhood development. But more-affluent communities were more likely to be exposed to ozone air pollutants.

Wodtke said the study does not pinpoint any leading air pollutants that are associated with high-poverty neighborhoods and lower test scores. Instead, it finds many air toxins have a weak association with both.

Experts pointed to mounting evidence that indicates that postnatal exposure to air pollution is associated with deficiencies in cognitive test scores. It has also been linked to attention-deficit/hyperactivity disorder (ADHD) symptoms and externalizing behavior problems in pediatric populations.

Emerging evidence also finds that exposure to fine particulate matter is correlated with reduced cortical thickness and thinner gray matter in the brain, which may influence information processing, learning and memory. Previous research has found that exposure to higher concentrations of small-particle air pollution is associated with poorer child behavioral functioning and cognitive performance.

Anjum Hajat, an associate professor in the department of epidemiology at the University of Washington, said the study “provides further evidence of the links between poverty, air pollution and health.”

“We have known for some time that living in high-poverty neighborhoods can be bad for your health, so being able to understand why that is allows us to better consider ways to intervene,” said Hajat, who was not part of the study.

Recent research has continued to show that children exposed to elevated levels of air pollution may be more likely to have poor academic skills in early adolescence, including in spelling, reading comprehension and math, according to studies conducted by Columbia University.

Hajat said while the link between air pollution and poverty is “pretty well established,” as are links between neighborhood poverty and other health effects, “this study links these different strands of research to give us one possible solution to improving child development.”


An earlier version of this article incorrectly said when the study was published. The study was published Wednesday. The article has been corrected.