Credit: Chris Goldberg/flickr

Pollution from busy roads may delay kids’ development

Study of children in New York state finds those living close to major roads are twice as likely to score low on communication tests

Children who live near major roads are more likely to score poorly on communication tests and experience development delays, according to a new study.


The research, published yesterday in the journal Environmental Research, suggests that exposure to traffic-related air pollution—such as small particulate matter (PM2.5) and ozone—in the womb or during early childhood may leave kids lagging in their ability to communicate, socialize and learn.

"Our results suggest that it may be prudent to minimize exposure to air pollution during pregnancy, infancy, and early childhood — all key periods for brain development," said Pauline Mendola, an epidemiology researcher at the National Institutes of Health and the study's senior author, in a statement.

Mendola and colleagues looked at the addresses of more than 5,800 children living in New York state (none were located in New York City) and calculated the distance to the nearest major roadway. They also looked at the mothers' work address during pregnancy and any daycare centers used, and used federal air toxics data to estimate possible exposures.

The researchers tested the kids' motor skills, communication, social behavior and problem solving every 4 to 6 months from when the children were 8 months old to 3 years old.

Children that lived fewer than 0.3 miles from a major roadway were twice as likely to fail at least one of their communication tests compared to children living more than a half mile away from a major road.

When they examined individual pollution exposures, kids exposed to higher amounts of ozone after birth had a 3.3 percent higher risk of failing parts of the development tests at 8 months old.

The stats worsened as children aged: those with higher estimated ozone exposure after birth had a 17.7 percent higher risk of overall testing failure at 2 years old, and a 7.6 percent higher risk of overall screening failure at 30 months old.

"Our findings suggest that these associations are present even at levels of exposure below current regulatory standards," the authors wrote.

Higher exposure to particulate matter and ozone in the womb were also associated with poorer testing, but the link was not as strong as for exposure when the kids were babies.

"It is not clear why exposure to pollutants after birth is linked to a higher risk of developmental delay," said lead author Sandie Ha, an assistant professor and researcher at the Department of Public Health at the University of California, Merced, in a statement. "However, unlike exposure during pregnancy, exposure during childhood is more direct and does not go through a pregnant woman's defenses."

The study doesn't mean dirty air from traffic causes developmental delays. Results from previous studies examining this link have been mixed. Also, the study was limited in that the researchers had to estimate air pollution exposures.

This troubling association is certainly plausible though—the authors point out that air pollution can trigger both oxidative stress and inflammation, both of which can impair proper brain development.

"While awaiting larger studies with personal air pollution assessment, efforts to minimize air pollution exposures during critical developmental windows may be warranted," the authors wrote.

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