Living near a major road may significantly increase a young child's risk of developmental delays, a new study claims.
It also found that children whose mothers were exposed during pregnancy to high levels of specific types of traffic-related air pollution had slightly higher odds of developmental delays.
"Our results suggest that it may be prudent to minimise exposure to air pollution during pregnancy, infancy and early childhood - all key periods for brain development," said senior study author Pauline Mendola. She's an investigator with the US National Institute of Child Health and Human Development, part of the US National Institutes of Health (NIH).
The researchers analysed data from more than 5 800 children whose development was screened every four to six months between the ages of 8 months and 36 months.
The screenings assessed small and large motor skills, communication, personal social functioning and problem-solving ability.
Compared to kids who lived more than a half-mile (more than 800m) from a major road, those who lived within a third of a mile were twice as likely to fail at least one screening of communication development.
Children born to mothers who were exposed to elevated levels of traffic-related fine particle pollution during pregnancy had a 1.6% to 2.7% higher risk of failing any developmental measure. Exposure during pregnancy to elevated ozone levels was associated with a 0.7% to 1.7% greater risk.
Higher exposure to ozone after birth was linked to a 3.3% higher risk of failing most developmental measures at 8 months; a 17.7% higher risk at 24 months; and a 7.6% higher risk at 30 months.
"It is not clear why exposure to pollutants after birth is linked to a higher risk of developmental delay," said study lead author Sandie Ha, an assistant professor of public health at the University of California, Merced.
"However, unlike exposure during pregnancy, exposure during childhood is more direct and does not go through a pregnant woman's defenses," she noted in an NIH news release.
While this study only found an association between proximity to roads and developmental delays, previous studies have linked air pollution exposure during pregnancy with low birthweight, preterm birth and stillbirth. Some studies also have found that children who live near freeways have a greater risk of autism and lower mental functioning.
A large percentage of the US population lives close to major roadways.
The study was published in April in the journal Environmental Research.
Image credit: iStock